VT43N4 [PERKINELMER]

Photoconductive Cells and Analog Optoisolators (Vactrols); 感光细胞和模拟光隔离器（ Vactrols ）


型号：	VT43N4
厂家：	PERKINELMER OPTOELECTRONICS
描述：	Photoconductive Cells and Analog Optoisolators (Vactrols) 感光细胞和模拟光隔离器（ Vactrols ）光电
文件：	总76页 (文件大小：1202K)
中文：	中文翻译
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Optoelectronics

Lighting

Imaging

Telecom

Sensors

Detectors and Sensors

Photoconductive Cells and

Analog Optoisolators (Vactrols®)

Specialty Lighting

Digital Imaging

Telecom

Sensors

Optoswitches, optical hybrids, custom assemblies, photodiodes, phototransistors, IR

emitters, and photoconductive cells for industrial, commercial, and consumer electron-

ics applications.

PerkinElmer Optoelectronics has the distinction of being one of the foremost manufacturers in

optoelectronics. Founded in 1947, PerkinElmer offers its customers over 35 years experience

in the development and application of optoelectronic devices. The product line is one of the

broadest in the industry, including a variety of standard catalog products as well as custom

design and manufacturing capabilities. Approximately 75% of the products shipped are cus-

tom designed and tested to serve the needs of specific OEM applications.

Three basic objectives guide PerkinElmer’s activities - Service, Quality, and Technology.

Our outstanding engineering staff, coupled with the implementation of modern material control

and manufacturing techniques, plus our commitment to quality, has gained PerkinElmer “certi-

fied” status with many major customers. Products are often shipped directly to manufacturing

lines without need for incoming QC at the customer’s facility. PerkinElmer’s products are verti-

cally integrated, from the growing of LED crystals, silicon die fabrication, package design, reli-

ability qualification, to assembly. Vertical integration is your assurance of consistent quality.

Recognizing the need for low-cost manufacturing to serve world markets, PerkinElmer

expanded its manufacturing/assembly operations into the Far East more than 20 years ago.

The combination of strong technology in processing at the St. Louis headquarters and low-

cost assembly operations in the Far East has allowed PerkinElmer to effectively serve all

markets, worldwide. PerkinElmer provides optical sensors, IR emitters and subassemblies for

such diverse applications as street light controls, cameras, smoke alarms, business

machines, automotive sensors, and medical equipment.

For pricing, delivery, data sheets, samples, or technical support please contact your

PerkinElmer Sales Office or direct your questions directly to the factory.

PerkinElmer Optoelectronics

10900 Page Avenue

St. Louis, Missouri 63132 USA

Tel: (314) 423-4900 Fax: (314) 423-3956

PerkinElmer Optoelectronics

www.perkinelmer.com/opto

Table of Contents

Photoconductive Cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

What is a Photoconductive Cell? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Photoconductive Cell Typical Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Why Use Photocells? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Photoconductive Cell Typical Application Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Selecting a Photocell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Photoconductive Cell Typical Characteristic Curves @ 25°C Type Ø Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Type Ø Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Photoconductive Cell Typical Characteristic Curves @ 25°C Type 3 Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Type 3 Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Photoconductive Cell Testing and General Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Production Testing of Photocells - PerkinElmer’s New Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Device Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Plastic Coated

VT900 Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

VT800 Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

VT800CT Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

VT400 Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Glass/Metal (Hermetic) Case

VT200 Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

VT300 Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

VT300CT Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

VT500 Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Application Notes—Photoconductive Cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

APPLICATION NOTE #1 Light - Some Physical Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

APPLICATION NOTE #2 Light Resistance Measurement Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

APPLICATION NOTE #3 Spectral Output of Common Light Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

APPLICATION NOTE #4 Spectral Matching of LEDs and Photoconductive Types . . . . . . . . . . . . . . . . . . . . . 24

APPLICATION NOTE #5 Assembly Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

APPLICATION NOTE #6 A Low Cost Light Source for Measuring Photocells . . . . . . . . . . . . . . . . . . . . . . . . . 25

APPLICATION NOTE #7 How to Specify a Low Cost Photocell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Table of Contents (Continued)

Analog Optical Isolators VACTROLS® . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

What Are Analog Optical Isolators? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Typical Applications of Analog Optical Isolators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Characteristics of Analog Optical Isolators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Transfer Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Response Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Distortion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Voltage Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Power Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Life and Aging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Storage Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Typical Transfer Characteristics (Resistance vs. Input Current) For Standard Vactrols . . . . . . . . . . . . . . . . . . 40

Analog Optoisolator Comparison Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Device Specifications

VTL5C1, 5C2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

VTL5C3, 5C4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

VTL5C2/2, 5C3/2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

VTL5C4/2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

VTL5C6, 5C7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

VTL5C8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

VTL5C9, 5C10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Application Notes—Analog Optical Isolators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

APPLICATION NOTE #1 Audio Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

APPLICATION NOTE #2 Handling and Soldering AOIs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

APPLICATION NOTE #3 Recommended Cleaning Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Custom and Semi-Custom Devices

Upon request, and where sufficient quantities are involved,

PerkinElmer Optoelectronics will test standard parts to your

unique set of specifications. The advantage of testing parts

under actual operating conditions is predictable performance in

the application.

PerkinElmer offers a broad line of standard photodiodes in a

wide variety of packages and sensitivities. Nevertheless, some

applications demand a totally custom device. Recognizing this

real need, PerkinElmer’s engineering, research, and sales

departments are geared for working with the customer from

initial concept through design, prototype, and volume production.

A custom design usually required the commitment of valuable

resources. PerkinElmer reviews requests for custom devices on

a case by case basis and reserves the right to decide if the

business potential warrants the undertaking of such a project.

The customer may be asked to share in the expense of

development.

PerkinElmer has designed and fabricated custom products for

many companies. PerkinElmer’s staff can work closely with the

customer and protect proprietary information. A custom design

usually required the commitment of valuable resources.

PerkinElmer reviews requests for custom devices on a case by

case basis and reserves the right to decide if the business

potential warrants the undertaking of such a project. The

customer may be asked to share in the expense of development.

PerkinElmer has designed and fabricated custom products for

many companies. PerkinElmer’s staff can work closely with the

customer and protect proprietary information.

Your inquiries to PerkinElmer should include electrical,

environmental, and mechanical requirements. Also, information

on anticipated volumes, price objectives, and lead times is

helpful since these often determine the choices of design and

tooling.

iii

Photoconductive Cells

What is a Photoconductive Cell?

Semiconductor light detectors can be divided into two major

categories: junction and bulk effect devices. Junction devices, when

operated in the photoconductive mode, utilize the reverse

characteristic of a PN junction. Under reverse bias, the PN junction

acts as a light controlled current source. Output is proportional to

incident illumination and is relatively independent of implied voltage as

shown in Figure 1. Silicon photodiodes are examples of this type

detector.

Figure 2

Bulk Effect Photoconductor (Photocell)

In contrast, bulk effect photoconductors have no junction. As shown in

Figure 2, the bulk resistivity decreases with increasing illumination,

allowing more photocurrent to flow. This resistive characteristic gives

bulk effect photoconductors a unique quality: signal current from the

detector can be varied over a wide range by adjusting the applied

voltage. To clearly make this distinction, PerkinElmer Optoelectronics

refers to it’s bulk effect photoconductors as photoconductive cells or

simply photocells.

Photocells are thin film devices made by depositing a layer of a

photoconductive material on a ceramic substrate. Metal contacts are

evaporated over the surface of the photoconductor and external

electrical connection is made to these contacts. These thin films of

photoconductive material have a high sheet resistance. Therefore, the

space between the two contacts is made narrow and interdigitated for

low cell resistance at moderate light levels. This construction is shown

in Figure 3.

Figure 1

Junction Photoconductor (Photodiode)

Figure 3

Typical Construction of a Plastic Coated Photocell

Photoconductive Cell Typical Applications

Why Use Photocells?

Photocells can provide a very economic and technically superior solution for many applications where the presence or absence of light is sensed

(digital operation) or where the intensity of light needs to be measured (analog operation). Their general characteristics and features can be

summarized as follows:

•

Lowest cost available and near-IR photo detector

Available in low cost plastic encapsulated packages as well as hermetic packages (TO-46, TO-5, TO-8)

Responsive to both very low light levels (moonlight) and to very high light levels (direct sunlight)

Wide dynamic range: resistance changes of several orders of magnitude between "light" and "no light"

Low noise distortion

Maximum operating voltages of 50 to 400 volts are suitable for operation on 120/240 VAC

Available in center tap dual cell configurations as well as specially selected resistance ranges for special applications

Easy to use in DC or AC circuits - they are a light variable resistor and hence symmetrical with respect to AC waveforms

Usable with almost any visible or near infrared light source such as LEDS; neon; fluorescent, incandescent bulbs, lasers; flame sources;

sunlight; etc

•

Available in a wide range of resistance values

Applications

Photoconductive cells are used in many different types of circuits and applications.

Analog Applications

•

Camera Exposure Control

Auto Slide Focus - dual cell

Photocopy Machines - density of toner

Colorimetric Test Equipment

Densitometer

Electronic Scales - dual cell

Automatic Gain Control - modulated light source

Automated Rear View Mirror

Digital Applications

•

Automatic Headlight Dimmer

Night Light Control

Oil Burner Flame Out

Street Light Control

Absence / Presence (beam breaker)

Position Sensor

Photoconductive Cell Typical Application Circuits

Ambient Light Measurement

Camera Exposure Meter (VT900)

Brightness Control (VT900)

DC Relay

Rear View Mirror Control (VT200)

Head Light Dimmer (VT300 or VT800)

AC Relay

Night Light Control (VT800 or VT900)

Street Light Control (VT400)

Flame Detector (VT400 or 500)

Object Sensing / Measurement

Beam Breaking Applications (VT800)

Security Systems (VT800 or VT900)

Colorimetric Test Equipment (VT200 or VT300)

Densitometer (VT200 or VT300)

Bridge Circuits

Auto Focus (VT300CT or VT800CT)

Electronic Scales (VT300CT or VT800CT)

Photoelectric Servo (VT300CT or VT800CT)

Selecting a Photocell

Specifying the best photoconductive cell for your application requires

an understanding of its principles of operation. This section reviews

some fundamentals of photocell technology to help you get the best

blend of parameters for your application.

composition of the detector. For a given type of photoconductor

material, at a given level of illumination, the photoconductive film will;

have a certain sheet resistivity. The resistance of the photocell at this

light level is determined by the electrode geometry.

R =

ρ (w / l )

When selecting a photocell the design engineer must ask two basic

questions:

where:

1. What kind of performance is required from the cell?

2. What kind of environment must the cell work in?

level H

= resistance of cell at light

sheet resistivity of

Performance Criteria

photoconductive film at light level

Sensitivity

w = width of electrode gap

l = length of electrode gap

The sensitivity of a photodetector is the relationship between the light

falling on the device and the resulting output signal. In the case of a

photocell, one is dealing with the relationship between the incident light

and the corresponding resistance of the cell.

Sheet sensitivity

(ρ

)

for

photoconductive films at 2 fc are in the range of 20 M per square.

Ω

The ratio w / l can be varied over a wide range in order to achieve

design goals. Typical values for w / l run from 0.002 to 0.5, providing

flexibility for terminal resistance and maximum cell voltage.

Spectral Response

Like the human eye, the relative sensitivity of a photoconductive cell is

dependent on the wavelength (color) of the incident light. Each

photoconductor material type has its own unique spectral response

curve or plot of the relative response of the photocell versus

wavelength of light.

Defining the sensitivity required for a specific application can prove to

be one of the more difficult aspects in specifying a photoconductor. In

order to specify the sensitivity one must, to some degree, characterize

the light source in terms of its intensity and its spectral content.

Within this handbook you will find curves of resistance versus light

intensity or illumination for many of PerkinElmer’s stock photocells. The

illumination is expressed in units of fc (foot candles) and lux. The light

source is an incandescent lamp. This lamp is special only in that the

spectral composition of the light it generates matches that of a black

body at a color temperature of 2850 K. This type of light source is an

industry agreed to standard.

The spectral response curves for PerkinElmer’s material types are

given in the handbook and should be considered in selecting a

photocell for a particular application.

Over the years PerkinElmer has developed different “types” of

photoconductive materials through modifications made to the chemical

Selecting a Photocell

Slope Characteristics

Plots of the resistance for the photocells listed in this catalog versus

light intensity result in a series of curves with characteristically different

slopes. This is an important characteristic of photocells because in

many applications not only is the absolute value of resistance at a

given light level of concern but also the value of the resistance as the

light source is varied. One way to specify this relationship is by the use

of parameter (gamma) which is defined as a straight line passing

through two specific points on the resistance curve. The two points

Likewise, for dual element photocells the matching factor, which is

defined as the ratio of the resistance of between elements, will

increase with decreasing light level.

used by PerkinElmer to define

fc).

are 10 lux (0.93 fc) and 100 lux (9.3

Log Ra – Log Rb

γ = -------------------------------------

Log a – Lob b

Dual Element Photocell Typical Matching Ratios

0.01 fc

0.1 fc

1.0 fc

10 fc

100 fc

Log(Ra ⁄ Rb)

= ------------------------------

Log(b ⁄ a)

0.63 – 1.39 0.74 – 1.27 0.75 – 1.25 0.76 – 1.20 0.77 – 1.23

Dark Resistance

As the name implies, the dark resistance is the resistance of the cell

under zero illumination lighting conditions. In some applications this

can be very important since the dark resistance defines what

maximum “leakage current” can be expected when a given voltage is

applied across the cell. Too high a leakage current could lead to false

triggering in some applications.

Applications for photocells are of one of two categories: digital or

analog. For the digital or ON-OFF types of applications such as flame

detectors, cells with steep slopes to their resistance versus light

intensity curves are appropriate. For analog or measurement types of

applications such as exposure controls for cameras, cells with shallow

slopes might be better suited.

The dark resistance is often defined as the minimum resistance that

can be expected 5 seconds after the cell has been removed from a

light intensity of 2 fc. Typical values for dark resistance tend to be in the

500k ohm to 20M ohm range.

Temperature Coefficient of Resistance.

Resistance Tolerance

Each type of photoconductive material has its own resistance versus

temperature characteristic. Additionally, the temperature coefficients of

photoconductors are also dependent on the light level the cells are

operating at.

The sensitivity of a photocell is defined as its resistance at a specific

level of illumination. Since no two photocells are exactly alike,

sensitivity is stated as a typical resistance value plus an allowable

tolerance. Both the value of resistance and its tolerance are specified

for only one light level. For moderate excursions from this specified

light level the tolerance level remain more or less constant. However,

when the light level the tolerance level remain more or less constant.

However, when the light level is decades larger or smaller than the

reference level the tolerance can differ considerably.

From the curves of the various types of materials it is apparent that the

temperature coefficient is an inverse funstin of light level. Thus, in order

to minimize temperature problems it is desirable to have the cell

operating at the highest light level possible.

Speed of Response

As the light level decreases, the spread in the tolerance level

increases. For increasing light levels the resistance tolerance will

tighten.

Speed of response is a measure of the speed at which a photocell

responds to a change from light-to-dark or from dark-to-light. The rise

time is defined as the time necessary for the light conductance of the

photocell to reach 1-1/e (or about 63%) of its final value.

Selecting a Photocell

The decay or fall time is defined as the time necessary for the light

conductance of the photocell to decay to 1/e (or about 73%) of its

illuminated state. At 1 fc of illumination the response times are typically

in the range of 5 msec to 100 msec.

This guide illustrates the fact that a photocell which has been stored for

a long time in the light will have a considerably higher light resistance

than if it was stored for a long time in the dark. Also, if a cell is stored

for a long period of time at a light level higher than the test level, it will

have a higher light resistance than if it was stored at a light level closer

to the test light level.

The speed of response depends on a number of factors including light

level, light history, and ambient temperature. All material types show

faster speed at higher light levels and slower speed at lower light

levels. Storage in the dark will cause slower response than if the cells

are kept in the light. The longer the photocells are kept in the dark the

more pronounced this effect will be. In addition, photocells tend to

respond slower in colder temperatures.

This effect can be minimized significantly by keeping the photocell

exposed to some constant low level of illumination (as opposed to

having it sit in the dark). This is the reason resistance specifications

are characterized after 16 hours light adept.

Environmental/Circuitry Considerations

Packaging

Light History

All photoconductive cells exhibit a phenomenon known as hysteresis,

light memory, or light history effect. Simply stated, a photocell tends to

remember its most recent storage condition (light or dark) and its

instantaneous conductance is a function of its previous condition. The

magnitude of the light history effect depends upon the new light level,

and upon the time spent at each of these light levels. this effect is

reversible.

In order to be protected from potentially hostile environments

photocells are encapsulated in either glass/metal (hermetic) package

or are covered with a clear plastic coating. While the hermetic

packages provide the greatest degree of protection, a plastic coating

represents a lower cost approach.

The disadvantage of plastic coatings is that they are not an absolute

barrier to eventual penetration by moisture. This can have an adverse

effect on cell life. However, plastic coated photocells have been used

successfully for many years in such hostile environments as street light

controls.

To understand the light history effect, it is often convenient to make an

analogy between the response of a photocell and that of a human eye.

Like the cell, the human eye’s sensitivity to light depends on what level

of light it was recently exposed to. Most people have had the

experience of coming in from the outdoors on a bright summer’s day

and being temporarily unable to see under normal room levels of

illumination. your eyes will adjust but a certain amount of time must

elapse first. how quickly one’s eyes adjust depends on how bright it

was outside and how long you remained outdoors.

Temperature Range

The chemistry of the photoconductive materials dictates an operating

and storage temperature range of –40°C to 75°C. It should be noted

that operation of the cell above 75°C does not usually lead to

catastrophic failure but the photoconductive surface may be damaged

leading to irreversible changes in sensitivity.

The following guide shows the general relationship between light

history and light resistance at various light levels. The values shown

were determined by dividing the resistance of a given cell, following

infinite light history (R ), by the resistance of the same cell following

The amount of resistance change is a function of time as well as

temperature. While changes of several hundred percent will occur in a

matter of a few minutes at 150°C, it will take years at 50°C to produce

that much change.

“infinite” dark history (R ). For practical purposes, 24 hours in the

dark will achieve R or 24 hours at approximately 30 fc will achieve

R .

Typical Variation of Resistance with Light History Expressed as a Ratio

Power Dissipation

at Various Test Illumination Levels.

During operation, a cell must remain within its maximum internal

temperature rating of 75°C. Any applied power will raise the cell’s

temperature above ambient and must be considered.

Illumination

/ R

Ratio

0.01 fc

1.55

0.1 fc

1.35

1.0 fc

1.20

10 fc

1.10

100 fc

1.10

LH DH

Selecting a Photocell

Many low voltage situations involve very little power, so that the

photocell can be small in size, where voltages and/or currents are

higher, the photocell must be physically larger so that the

semiconductor film can dissipate the heat.

Maximum Cell Voltage

At no time should the peak voltage of the cell exceed its maximum

voltage. the designer should determine the maximum operating or

peak voltage that the cell will experience in the circuit and choose an

appropriately rated cell. Typical voltage rates range from 100V to 300V.

The following curve of power dissipation versus ambient temperature

describes the entire series of cells for operation in free air at room

ambient (25°C). Note that regardless the size, all photocells derate

linearly to zero at an ambient temperature of 75°C. The adequate heat

sinks can increase the dissipation by as much as four times the levels

shown in this graph.

What Type of Material is Best?

Each specific material type represents a trade off between several

characteristics. Selecting the best material is a process of determining

which characteristics are most important tin the application.

PerkinElmer’s standard photocells in this catalog are manufactured

using one of two different material types offered: type “Ø” or type “3”.

In general, material type “Ø” is used for applications such as

nightlights, automotive sensors. Material type “3” is primarily used in

camera, streetlight control, and flame detector applications.

Photoconductive Cell Typical Characteristic Curves

@ 25°C Type Ø Material

Type Ø Material

This is a general purpose material. Its characteristics include a good temperature coefficient and fast response time, especially at very

low light levels. Cells of this type have relatively low dark history. Type Ø material is often used in lighting controls such as nightlights,

and security lighting.

The resistance for any standard catalog cell is controlled at only one light level. If the resistance at other light levels is a concern,

please contact the factory.

To obtain the typical resistance versus illumination characteristic

for a specific part number:

Resistance vs. Illumination

1. Look up 2 footcandle resistance in table.

2. Insert resistance given and draw a curve through that point

and parallel to the closest member of the family of curves

shown for the appropriate type of photo-sensitive material.

Response Time vs. Illumination

(Rise Time)

Response Time vs. Illumination

(Decay Time)

Photoconductive Cell Typical Characteristic Curves

@ 25°C Type Ø Material

Relative Spectral Response

Relative Resistance vs. Temperature

Photoconductive Cell Typical Characteristic Curves

@ 25°C Type 3 Material

Type 3 Material

This is a high speed material with a spectral response closely approximating the human eye. This material is well suited for switching

from one light level to another and offers our best temperature stability and response time. This material is often used in cameras and

industrial controls.

The resistance for any standard catalog cell is controlled at only one light level. If the resistance at other light levels is a concern,

please contact the factory.

To obtain the typical resistance versus illumination characteristic

for a specific part number:

Resistance vs. Illumination

1. Look up 2 footcandle resistance in table.

2. Insert resistance given and draw a curve through that point

and parallel to the closest member of the family of curves

shown for the appropriate type of photo-sensitive material.

Response Time vs. Illumination

(Rise Time)

Response Time vs. Illumination

(Decay Time)

Photoconductive Cell Typical Characteristic Curves

@ 25°C Type 3 Material

Relative Spectral Response

Relative Resistance vs. Temperature

Photoconductive Cell Testing and General Notes

Production Testing of Photocells - PerkinElmer’s New Approach

Historically within this industry, vendors have set their

production testers to the limits specified on the

customer’s print. Measurement errors due to ambient

temperature, calibration of light source, light history

effect, plus any tester errors have always guaranteed that

a certain percentage of the cells shipped are out of

specification.

This practice is incompatible with the realities of today’s

marketplace, where quality levels are being measured in

parts per million.

With this new catalog, PerkinElmer is taking the

opportunity to correct this situation. for parts in this

catalog, PerkinElmer has pulled in the test limits on our

production testers to compensate for measurement

errors.

General Notes

(Refer to the following data specification pages.)

Photocells are supplied categorized into groups by resistance. All groups must be purchased together and PerkinElmer maintains

the right to determine the product mix among these groups.

Dimension controlled at base of package.

Photocells are tested at either 1 fc or 10 lux. 2 fc typical values shown in the tables are for reference only.

Cells are light adapted at 30 - 50 fc.

The photocell “grid” pattern can vary from that shown. PerkinElmer reserves the right to change mix grid patterns on any standard

product.

The resistance for any standard cell is controlled at only one light level. If the resistance at other light levels is a concern, please

contact the factory.

Photoconductive Cell

VT900 Series

PACKAGE DIMENSIONS inch (mm)

ABSOLUTE MAXIMUM RATINGS

Parameter

Symbol

Rating

Units

Continuous Power Dissipation

Derate Above 25°C

1.6

mW/°C

∆P / ∆T

Temperature Range

Operating and Storage

–40 to +75

°C

ELECTRO-OPTICAL CHARACTERICTICS @ 25°C (16 hrs. light adapt, min.)

3 6

Resistance (Ohms)

Sensitivity

Response Time @ 1 fc

(ms, typ.)

(γ, typ.)

10 lux

2850 K

2 fc

Dark

2850 K

Typ.

Maximum

Voltage

(V, pk)

Part

Number

Material

Type

LOG (R10/R100)

-----------------------------------

LOG (100/10)

Min.

Typ.

Max.

Min.

sec.

Rise (1-1/e) Fall (1/e)

VT9ØN1

VT9ØN2

VT9ØN3

VT9ØN4

VT93N1

VT93N2

VT93N3

VT93N4

VT935G

Group A

6 k

12 k

25 k

50 k

12 k

24 k

50 k

100 k

12 k

24 k

18 k

36 k

6 k

12 k

25 k

50 k

12 k

24 k

50 k

100 k

200 k

500 k

1 M

0.80

0.85

0.90

100

50 k

75 k

100 k

24 k

150 k

36 k

2 M

300 k

500 k

48 k

72 k

100 k

200 k

150 k

300 k

10 k

20 k

31 k

18.5 k

29 k

27 k

38 k

50 k

9.3 k

15 k

20 k

1 M

0.90

100

Group B

Group C

40.5 k

See page 13 for notes.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

Photoconductive Cell

VT800 Series

PACKAGE DIMENSIONSinch (mm)

ABSOLUTE MAXIMUM RATINGS

Parameter

Symbol

Rating

Units

Continuous Power Dissipation

Derate Above 25°C

175

3.5

mW/°C

∆P / ∆T

Temperature Range

Operating and Storage

–40 to +75

°C

ELECTRO-OPTICAL CHARACTERICTICS @ 25°C (16 hrs. light adapt, min.)

3 6

Resistance (Ohms)

Sensitivity

Response Time @ 1 fc

(ms, typ.)

(γ, typ.)

10 lux

2850 K

2 fc

Dark

2850 K

Typ.

Maximum

Voltage

(V, pk)

Part

Number

Material

Type

OG (R10/R100)

-----------------------------------

LOG (100/10)

Min.

Typ.

Max.

Min.

sec.

Rise (1-1/e) Fall (1/e)

VT8ØN1

VT8ØN2

VT83N1

VT83N2

VT83N3

VT83N4

4 k

8 k

16 k

12 k

28 k

48 k

100 k

12 k

24 k

18 k

36 k

72 k

150 k

4 k

8 k

100 k

500 k

100 k

500 k

1 M

0.80

0.95

100

200

100

200

6 k

12 k

24 k

50 k

14 k

24 k

50 k

2 M

See page 13 for notes.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

VT800CT Series

Photoconductive Cell

Dual Element

PACKAGE DIMENSIONS inch (mm)

VT800CT Series

ABSOLUTE MAXIMUM RATINGS

Parameter

Symbol

Rating

Units

Continuous Power Dissipation (Per Element)

Derate Above 25°C

1.6

mW/°C

∆P / ∆T

Temperature Range

Operating and Storage

–40 to +75

°C

ELECTRO-OPTICAL CHARACTERICTICS @ 25°C (16 hrs. light adapt, min.)

3 6

Resistance Per Element (Ohms)

Sensitivity

Response Time @ 1 fc

(ms, typ.)

(γ, typ.)

10 lux

2850 K

2 fc

2850 K

Dark

Matching

@ 10 Lux

Maximum

Voltage

(V, pk)

Part

Number

Material

Type

OG (R10/R100)

-----------------------------------

LOG (100/10)

/ R

1–2 2–3

Min.

30 k

Typ.

60 k

Max.

90 k

Typ.

Min.

1 M

sec.

Rise (1-1/e) Fall (1/e)

VT83CT

30 k

0.70 – 1.30

0.90

100

See page 13 for notes.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

Photoconductive Cell

VT400 Series

PACKAGE DIMENSIONS inch (mm)

ABSOLUTE MAXIMUM RATINGS

Parameter

Symbol

Rating

Units

Continuous Power Dissipation

Demand (20 minutes)

Derate Above 25°C

400

600

8.0

mW/°C

∆P / ∆T

Temperature Range

Operating and Storage

–40 to +75

°C

ELECTRO-OPTICAL CHARACTERICTICS @ 25°C (16 hrs. light adapt, min.)

3 6

Resistance (Ohms)

Sensitivity

Response Time @ 1 fc

(ms, typ.)

(γ, typ.)

1 fc

6500 K

2 fc

Dark

2850 K

Typ.

Maximum

Voltage

(V, pk)

Part

Number

Material

Type

OG (R10/R100)

-----------------------------------

LOG (100/10)

Min.

Typ.

Max.

Min.

sec.

Rise (1-1/e) Fall (1/e)

VT43N1

VT43N2

VT43N3

VT43N4

4 k

8 k

12 k

24 k

—

300 k

500 k

0.90

250

400

16 k

32 k

66 k

16 k

33 k

48 k

100 k

See page 13 for notes.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

Photoconductive Cell

VT200 Series

PACKAGE DIMENSIONS inch (mm)

ABSOLUTE MAXIMUM RATINGS

Parameter

Symbol

Rating

Units

Continuous Power Dissipation

Derate Above 25°C

1.0

∆P / ∆T

mW/°C

Temperature Range

Operating and Storage

–40 to +75

°C

ELECTRO-OPTICAL CHARACTERICTICS @ 25°C (16 hrs. light adapt, min.)

3 6

Resistance (Ohms)

Sensitivity

Response Time @ 1 fc

(ms, typ.)

(γ, typ.)

10 lux

2850 K

2 fc

Dark

2850 K

Typ.

Maximum

Voltage

(V, pk)

Part

Number

Material

Type

LOG (R10/R100)

-----------------------------------

LOG (100/10)

Min.

Typ.

Max.

Min.

sec.

Rise (1-1/e) Fall (1/e)

VT2ØN1

VT2ØN2

VT2ØN3

VT2ØN4

VT23N1

VT23N2

VT23N3

8 k

16 k

34 k

72 k

152 k

40 k

86 k

180 k

24 k

52 k

8 k

200 k

500 k

1 M

0.80

0.85

100

200

100

16 k

36 k

76 k

20 k

42 k

90 k

17 k

36 k

76 k

20 k

43 k

90 k

108 k

230 k

60 k

2 M

500 k

1 M

130 k

270 k

2 M

See page 13 for notes.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

Photoconductive Cell

VT300 Series

PACKAGE DIMENSIONS inch (mm)

ABSOLUTE MAXIMUM RATINGS

Parameter

Symbol

Rating

Units

Continuous Power Dissipation

Derate Above 25°C

125

2.5

mW/°C

∆P / ∆T

Temperature Range

Operating and Storage

–40 to +75

°C

ELECTRO-OPTICAL CHARACTERICTICS @ 25°C (16 hrs. light adapt, min.)

3 6

Resistance (Ohms)

Sensitivity

Response Time @ 1 fc

(ms, typ.)

(γ, typ.)

10 lux

2850 K

2 fc

Dark

2850 K

Typ.

Maximum

Voltage

(V, pk)

Part

Number

Material

Type

OG (R10/R100)

-----------------------------------

LOG (100/10)

Min.

Typ.

Max.

Min.

sec.

Rise (1-1/e) Fall (1/e)

VT3ØN1

VT3ØN2

VT3ØN3

VT3ØN4

VT33N1

VT33N2

VT33N3

6 k

12 k

24 k

48 k

100 k

40 k

80 k

160 k

18 k

36 k

6 k

200 k

500 k

1 M

0.75

0.80

0.90

100

200

300

100

200

12 k

24 k

50 k

20 k

40 k

80 k

12 k

24 k

50 k

20 k

40 k

80 k

72 k

150 k

60 k

2 M

500 k

1 M

120 k

240 k

2 M

See page 13 for notes.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

VT300CT Series

Photoconductive Cell

Dual Element

PACKAGE DIMENSIONS inch (mm)

VT300CT Series

ABSOLUTE MAXIMUM RATINGS

Parameter

Symbol

Rating

Units

Continuous Power Dissipation (Per Element)

Derate Above 25°C

1.0

mW/°C

∆P / ∆T

Temperature Range

Operating and Storage

–40 to +75

°C

ELECTRO-OPTICAL CHARACTERICTICS @ 25°C (16 hrs. light adapt, min.)

3 6

Resistance Per Element (Ohms)

Sensitivity

Response Time @ 1 fc

(ms, typ.)

(γ, typ.)

10 lux

2850 K

2 fc

2850 K

Dark

Matching

10 Lux

Maximum

Voltage

(V, pk)

Part

Number

Material

Type

OG (R10/R100)

-----------------------------------

LOG (100/10)

/ R

1–2 2–3

Min.

Typ.

Max.

Typ.

Min.

sec.

Rise (1-1/e) Fall (1/e)

VT3ØCT

VT33CT

10 k

60 k

20 k

30 k

10 k

60 k

500 k

1 M

0.70 – 1.30

0.80

0.90

200

120 k

180 k

See page 13 for notes.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

Photoconductive Cell

VT500 Series

PACKAGE DIMENSIONS inch (mm)

ABSOLUTE MAXIMUM RATINGS

Parameter

Symbol

Rating

Units

Continuous Power Dissipation

Derate Above 25°C

500

mW/°C

∆P / ∆T

Temperature Range

Operating and Storage

–40 to +75

°C

ELECTRO-OPTICAL CHARACTERICTICS @ 25°C (16 hrs. light adapt, min.)

3 6

Resistance (Ohms)

Sensitivity

Response Time @ 1 fc

(ms, typ.)

(γ, typ.)

10 lux

2850 K

2 fc

Dark

2850 K

Typ.

Maximum

Voltage

(V, pk)

Part

Number

Material

Type

OG (R10/R100)

-----------------------------------

LOG (100/10)

Min.

Typ.

Max.

Min.

sec.

Rise (1-1/e) Fall (1/e)

VT5ØN1

VT5ØN2

VT5ØN3

VT53N1

VT53N2

VT53N3

4 k

8 k

16 k

32 k

76 k

132 k

12 k

24 k

48 k

96 k

200 k

4 k

8 k

200 k

500 k

1 M

0.75

0.80

0.85

200

300

200

300

16 k

32 k

66 k

16 k

38 k

66 k

1 M

2 M

3 M

See page 13 for notes.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

Application Notes—Photoconductive Cells

wavelength is defined as the distance a wave travels in one cycle.

APPLICATION NOTE #1

Light - Some Physical Basics

Since the wavelengths of light are very short they are normally

-9

measured in nanometers, one nanometer being equal to 1 x 10

meters.

Light is produced by the release of energy from the atoms of a material

when they are excited by heat, chemical reaction or other means. Light

travels through space in the form of an electromagnetic wave.

The spectral response of PerkinElmer’s photoconductors are specified

by lots of relative response versus wavelength (color) for various

material types.

A consequence of this wave-like nature is that each “color” can be

completely defined by specifying its unique wavelength. The

700

400

Ultraviolet

Visible Light

Infrared

(To X-rays and Gamma Rays)

(To Radar Waves)

Violet

Red

Wavelength

Violet

Below 450 nm

450 - 500 nm

500 - 570 nm

570 - 590 nm

590 - 610 nm

610 - 700 nm

Blue

Green

Yellow

Orange

Red

Natural Illuminance

Room Illumination

Sky Condition

Direct Sunlight

Light Level (Typical)

Lighting Condition

Candle - Lit Room

Light Level (Typical)

10000 fc

1000 fc

1 fc

5 fc

10 fc

Overcast Day

Twilight

Auditorium

Classroom

30 fc

Full Moon

0.1 fc

Inspection Station

Hospital Operating Room

250 fc

Clear Night Sky (moonless)

0.001 fc

500 - 1000 fc

Application Notes—Photoconductive Cells

APPLICATION NOTE #2

APPLICATION NOTE #3

Light Resistance Measurement Techniques

Spectral Output of Common Light Sources

The light resistance or “on” resistance (RON) of a photoconductor cell

is defined as the resistance of the cell as measured at a special light

level using a light source with a known output spectrum. Furthermore,

the cell must be “light adapted” for a specific period of time at an

established level of illumination in order to achieve repeatable results.

Incandescent lamps can be considered as black body radiators whose

spectral output is dependent on their color temperature. The sun has

approximately the same spectral radiation distribution as that of a black

body @ 5900 K. However, as viewed from the surface of the earth, the

sun's spectrum contains H O and CO absorption bands.

The industry standard light source used for light resistance

measurements is a tungsten filament lamp operating at a color

temperature of 2850 K. Specifying the 2850 K color temperature for the

light source fixes the spectral output (i.e. the tungsten filament light has

fixed amounts of blue, green, red, and infrared light).

For consistency and ease of comparing different cells, PerkinElmer

lists light resistance values for its photocells at two standard light

levels: 2 fc (footcandles) and at 10 lux. The footcandle is the old,

historical unit for measuring light intensity and is defined as the

illumination produced when the light from one standard candle falls

normally on a surface at a distance of one foot. The lux (the metric unit

of light measurement) is the illumination produced when the light from

one candle falls normally on a surface of one meter. The conversion

between footcandle and lux. is as follows:

Black Body Sources Output vs. Wavelength

Fluorescent lamps exhibit a broad band spectral output with narrow

peaks in certain parts of the spectrum. Shown below is a plot of the

light output of a typical daylight type fluorescent tube.

1.0 fc = 10.76 lux

1.0 lux = 0.093 fc

As explained in the section on “Selecting a Photocell”, the “light

history” effect necessitates the pre-conditioning of the cell before a

light resistance measurement is made. PerkinElmer stores all cells at

room temperature for 16 hours minimum at 30 – 50 fc (about 320 - 540

lux) prior to making the test measurement.

Sometimes the design engineer or user does not have access to the

precision measurement equipment necessary to determine the light

levels or light intensities of the application. Should this prove to be a

problem, calibrated photocell samples with individual data can be

provided by PerkinElmer.

Fluorescent Lamp Output vs. Wavelength

Due to their long operating lifetimes, small size, low power

consumption, and the fact they generate little heat, LEDs are the light

sources of choice in many applications. When biased in the forward

direction LEDs emit light that is very narrow in spectral bandwidth (light

of one color). The “color” of the light emitted depends on which

semiconductor material was used for the LED.

Application Notes—Photoconductive Cells

LED Light Sources

The LED/photocell matching factors listed are independent of power

output from the LEDs. In order to get a real feel on how well any LED/

photocell pair couple together, the power output from the LED at a

particular forward drive current must be considered.

LED Type

Color

GaP

GaAsP/GaP

GaAsP/GaAs

AIGaAs

GREEN

YELLOW

ORANGE

RED

569 nm

585 nm

635 nm

655 nm

660 nm

697 nm

880 nm

940 nm

Normalized LED/Photocell Matching

LED Type

λ (nm)

Type Ø Material Type 3 Material

RED

GaP

GaAsP/GaP

GaAsP/GaAs

AIGaAs

569

39%

60%

49%

31%

47%

—

40%

52%

38%

27%

31%

—

GaP/GaP

GaAIAs

RED

INFRARED

635

655

GaAs

APPLICATION NOTE #4

Spectral Matching of LEDs and

Photoconductive Types

GaP/GaP

GaAIAs

697

880

940

GaAs

—

The intensity of the light being emitted by visible LEDs is often given in

units of millicandela. Millicandela is photometric unit of measure which

assumes the human eye as the detector. For most detectors other than

the human eye the most convenient system for measurement is the

radiometric system. Listed below is the typical light power output of

some LEDs measured at two different forward drive currents. Note that

LEDs of a given type can show a 5:1 manufacturing spread in power

outputs.

Since light sources and light detectors are almost always used

together the designer must take into consideration the optical coupling

of this system or the ability of the detector to “see” the light source.

In order to have good optical coupling between the emitter and the

conductor the spectral output of the light source must, to some degree,

overlap the spectral response of the detector. If the design involves the

use of a light source with a broad band spectral output the designer is

assured that the photocell will have good response to the light. This

may not be the case when an LED light source is employed. LEDs emit

their light within a very narrow spectral band so that they are often

considered to be emitting at only on (peak) wavelength.

Power Output

LED Type

Color

λ (nm)

I = 1 mA

I = 10 mA

GaP

GaAsP/GaP

GaAsP/GaAs

AIGaAs

GREEN

YELLOW

ORANGE

RED

569 nm

585 nm

635 nm

655 nm

660 nm

697 nm

880 nm

940 nm

1.2 µW

0.3 µW

3.2 µW

6.2 µW

33.8 µW

54.3 µW

76.8 µW

35.5 µW

24.1 µW

26.2 µW

Spectral matching factors were calculated for a number of different

LEDs and the photoconductor material types manufactured by

PerkinElmer. Each matching factor was derived by multiplying the

detector response curves by the LED spectral output curve and then

measuring the resulting area.

101.9 µW

102.1 µW

445.1 µW

296.2 µW

1512.3 µW

675.0 µW

RED

GaP/GaP

GaAIAs

RED

INFRARED

GaAs

Application Notes—Photoconductive Cells

Factoring in the power outputs of the LEDs, in this case at a forward

drive current of 10 ma, coupling factors (matching factor multiplied by

power output) for the various LED/material type combinations can be

generated.

Storage in the dark will change both the sensitivity and decay time of

the cell.

APPLICATION NOTE #6

A Low Cost Light Source for Measuring

Photocells

Normalized LED/Photocell Coupling Factors @ 10 mA

LED Type

λ (nm)

Type Ø

Type 3

GaP

GaAsP/GaP

GaAsP/GaAs

AIGaAs

569

The Light Source used in the measurement of photocell resistance

635

655

17%

11%

47%

—

13%

must be characterized for intensity and spectral composition.

PerkinElmer uses a tungsten filament lamp having a spectral output

approximating a black body @ 2850 K with a known candlepower

output at a specified voltage and current.

35%

31%

—

GaP/GaP

GaAIAs

697

880

940

While calibrated lamps of this type are available from the National

Institute of Standards and Technology (formerly NBS) and private

testing labs, a low cost alternative is to use a 100 W, inside frosted,

tungsten filament lamp available from any home or hardware store.

Such a lamp operated at 120 VAC will produce approximately 90

candlepower (cp) of illumination and a color temperature of 2700 K to

2800 K.

GaAs

—

Once gain, this data is intended as a general guide. LED power

outputs can vary 5:1 between manufacturer lots.

APPLICATION NOTE #5

Assembly Precautions

The relationship between candlepower and footcandle is:

When soldering the cell leads take all measures possible to limit the

amount of heating to the photocell. The maximum recommended

soldering temperature is 250°C with a solder duration of 5 seconds.

Heat sink the LEDs if possible. Keep soldering iron 1/16 inch (1.6 mm)

minimum from base of package when soldering.

candle power

(distance in feet)²

footcandle = ---------------------------------------

Since this equation assumes a point source of light, the distance

between lamp and detector should be at least five times the lamp

diameter.

Avoid chemicals which can cause metal corrosion. Do not clean the

plastic coated cells with organic solvents (ketone types). Check with

factory for specific cleaning recommendations.

There are some characteristics of incandescent lamps which should

be noted:

Finally refrain from storing the cells under high temperature and/or

humidity conditions. If cells are stored in the dark for any length of time

please “light adept” before testing (see section on Light History Effect).

1. Color temperature increases with increasing wattage.

2. When operated at a constant current, light output rises with time.

Application Notes—Photoconductive Cells

APPLICATION NOTE #7

Lower Cost

Factor

Higher Cost

How to Specify a Low Cost Photocell

Plastic

Broad

Small

Packaging

Resistance Range

Package Size

Scheduling

Glass/Metal

Narrow

Sometimes the demands of the application such as power dissipation,

“on” resistance, voltage, temperature coefficient, etc. limit the selection

of the photocell to one particular device. However, more common is the

case where any number of photocell types can be used, especially if

minor changes are undertaken at an early enough point in the circuit

design. In these cases, price is often the deciding factor.

Large

Open Order with

Scheduled Releases

Released Orders

Standard Tests

Testing

Special Tests

Many factors influence price. In order to give some guidance and

weight to these factors the reader is referred to the following table

which is meant to serve as a general guide.

Analog Optical Isolators VACTROLS®

What Are Analog Optical Isolators?

PerkinElmer Optoelectronics has been a leading manufacturer of

analog optical isolators for over twenty years and makes a broad range

of standard parts under its trademark VACTROL®.

They must be protected from excessive forward current due to the low

dynamic resistance in the forward direction. The forward characteristic

of an LED typically used in VACTROLs is shown below.

There are many kinds of optical isolators, but the most common is the

LED/phototransistor type. Other familiar types use output elements

such as light sensitive SCRs, Triacs, FETs, and ICs. The major

application for these silicon based devices is to provide electrical

isolation of digital lines connected between different pieces of

equipment. The principle of operation is very simple. When an input

current is applied to the LED, the output phototransistor turns on. The

only connection between the LED and phototransistor is through

light—not electricity, thus the term optical isolator. These optical

isolators are primarily digital in nature with fast response times suitable

for interfacing with logic gates. Rise and fall times of a few

microseconds, faster for some isolators, are typical.

LED Forward Characteristics

Output Element

The analog optical isolator (AOI) also uses an optical link between

input and output. The input element is an LED and the output element

is always photoconductive cell or simply photocell. Together, the

coupled pair act as an electrically variable potentiometer. since the

output element of the AOI is a resistor, the voltage applied to this

output resistor may be DC and/or AC and the magnitude may be as

low as zero or as high as the maximum voltage rating. Because the

input will control the magnitude of a complex waveform in a

proportional manner, this type of isolator is an analog control element.

AOIs may be used in the ON-OFF mode but the fastest response time

is only in the millisecond range. A level sensitive Schmitt trigger is

required between the AOI and logic gates when used in digital circuits.

The figure below shows the circuit diagram of a standard AOI.

The output element in all PerkinElmer’s AOIs is a light dependent

resistor (LDR), also called a photoconductor or photocell. Photocells

are true resistors.

These passive resistors are made from a light sensitive polycrystalline

semiconductor thin film which has a very high electron/photon gain.

There are no P/N junctions in a photocell, making it a bilateral device.

The resistance of the photocell depends on the amount of light falling

on the cell. For a given illumination, the amount of electrical current

through the cell depends on the voltage applied. This voltage may be

either AC or DC. Thus, the photocell is the ideal low distortion output

element for an analog optoisolator.

A complete discussion of photoconductive cells can be found in the

first section of this book.

AOI Circuit Diagram

Input Element

Light emitting diodes used in AOIs are usually visible LEDs best

matching the sensitivity spectrum of the photocell output element.

LEDs are the ideal input element in most applications. They require

low drive current and voltage, respond very fast and have virtually

unlimited life. They are very rugged and are unaffected by shock and

vibration. Since the LED is a diode, it conducts in one direction only.

What Are Analog Optical Isolators?

The table illustrates the fact that the resistance of a photocell can

Light History Considerations

increase substantially as it transitions from dark adapted state to a light

adapted state. The table shows that the Type 1 photocell can increase

resistance by a factor of more than three times as it light adapts up to

0.1 fc. In some applications, this can be an important consideration. In

general, the magnitude of this effect is larger for types 1, 4, and 7 than

for types Ø, 2, and 3.

Photoconductive cells exhibit a phenomenon knows as hysteresis, light

memory, or light history effect. Special consideration must be given to

this characteristic in the analog optoisolator because the

photoconductive element is normally in the dark. This will lead to

having the photocell initially in a “dark adapted” state in many

conditions.

Each specific material type represents a tradeoff between several

characteristics. Selecting the best material is a process of determining

what characteristics are most important in the application. The chart

gives some appreciation for the general interrelationships between the

material types and their properties.

The light levels that are seen by the photocell in many analog

optoisolator applications are quite low, ranging from 0.1 to 1.0 fc. The

effect of this combination of dark adapt and low light levels will be seen

in the following table.

The table shows the relationship between light history and light

resistance at various light levels for different material types. The values

shown were determined by dividing the resistance of a given cell,

following “infinite” light history (R ), by the resistance of the same cell

following infinite dark history (R ). For practical purposes, 24 hours in

the dark will achieve R or 24 at approximately 30 fc will achieve R .

Variation of Resistance with Light History Expressed as a

Ratio R /R at Various Test Illumination Levels

LH DH

Illumination (fc)

Material

Type

0.01

0.1

1.0

100

Type Ø

Type 1

Type 2

Type 3

Type 4

Type 7

1.60

5.50

1.50

4.50

1.87

1.40

3.10

1.30

3.00

1.50

1.20

1.50

1.20

1.70

1.25

1.10

1.15

1.10

1.05

1.10

1.08

What Are Analog Optical Isolators?

Material Characteristics

(General Trends)

Types 2 & 3

Type Ø

Type 7

Type 4

Type 1

Lower

Higher

Slower

Lower

Temperature Coefficient

Sheet Resistivity

Higher

Lower

Faster

Higher

Larger

Speed of Response

Resistance Slope

Smaller

Light History Effect

Relative Resistance vs. Temperature

Type Ø Material

Type 2 Material

Relative Resistance vs. Temperature

Type 3 Material

Type 1 Material

What Are Analog Optical Isolators?

Relative Resistance vs. Temperature

Type 4 Material

Relative Resistance vs. Temperature

Type 7 Material

Typical Applications of Analog Optical Isolators

Why Use Analog Optical Isolators?

PerkinElmer Optoelectronics’ line of analog optical isolators (AOIs) consists of a light tight package which houses a light source and

one or more photoconductive cells. Through control of the input current or voltage applied to the AOI, the output resistance can be

varied. The output resistance can be made to switch between an “on” and “off” state or made to track the input signal in an analog

manner. Because a small change in input signal can cause a large change in output resistance, AOIs have been found to provide a

very economic and technically superior solution for many applications. Their general characteristics and salient features can be

summarized as follows:

•

High input-to-output voltage isolation

True resistance element output

Single or dual element outputs available

Low cost

Suitable for AC or DC use

Wide range of input to output characteristics

Low drive current

Low “on” resistance, high “off” resistance

Complete solid-state construction

Applications

Analog Optical Isolators are used in many different types of circuits and applications. Here is a list of only a few examples of where

AOIs have been used.

•

DC isolators

Feedback elements in automatic gain control circuits

Audio limiting and compression

Noiseless switching

Logic interfacing

Remote gain control for amplifiers

Photochoppers

Noiseless potentiometers

Typical Applications of Analog Optical Isolators

Typical Application Circuits

Automatic Gain Control (AGC)

Remote Gain Control

Noiseless Switching/Logic Interfacing

(See Application Note #1)

Audio Applications

Characteristics of Analog Optical Isolators

applied, the photocells resistance drops very fast, typically reaching

63% (1-1/e conductance) of its final values in under 10 msec.

Transfer Characteristics

The light output of an LED is proportional to the input drive current, I .

When the light is removed, the resistance increases initially at an

exponential rate, approximately tripling in a few milliseconds. The

resistance then increases linearly with time.

Some LEDs will begin to radiate useful amounts of light output at

forward currents as low as 10 µA. These same LEDs can be driven at

50 mA with no degradation in performance.

The fast turn-on and slow turn-off characteristics can be used to

advantage in many applications. This is especially true in audio

applications where a fast turn-on (attack) and a slow turn-off (release)

is preferred. For example, the typical AOI can be made to turn-on in

100 to 1000 µsec. In a limited circuit this is fast enough to catch high

peak amplitudes but not so fast as to cause obvious clipping. The turn-

off will take as much as 100 times longer so the audio circuit will return

to a normal gain condition without a disturbing “thump” in the speaker.

A transfer curve of output resistance versus input light current for a

typical AOI is shown in Figure 1. AOIs not only possess a large

dynamic range, but the output resistance tracks the input current in a

somewhat linear manner over a range of two or more decades.

This characteristic makes the AOI suitable for use in a very broad

range of applications, especially in audio circuits where they are used

for switching, limiting, and gating. For a more extensive discussion on

AOIs in audio circuits, refer to Application Notes #1.

Response Time

AOIs are not high speed devices. Speed is limited by the response

time of the photocell. With rise and fall times on the order of 2.5 to

1500 msec, most AOIs have bandwidths between 1 Hz and 200 Hz.

Figure 2. Resistance vs. Time

Noise

The sources of electrical noise in the output element of AOIs are the

same as for any other type of resistor.

Figure 1. Transfer Curves (25°C)

One source of noise is thermal noise, also known as Johnson or

“white” noise, which is caused by the random motion of free electrons

in the photoconductive material.

One of the characteristics of photocells is that their speed of response

increases with increasing levels of illumination. Thus the bandwidth of

Vactrols is somewhat dependent upon the input drive level to the LED.

In general, the higher the input drive the wider the bandwidth.

The turn-off time and turn-on time of photocells are not symmetrical.

The turn-on time can be an order of magnitude faster than the turn-off

time. In the dark (no input), the resistance of the cell is very high,

typically on the order of several megohms. When light is suddenly

1. For a more comprehensive discussion on the turn-on and turn-

off characteristics of photocells and how response time is effect-

ed by light level, see the Photoconductive Cell section of this cat-

alog.

Characteristics of Analog Optical Isolators

Some major characteristics of Johnson noise are that it is:

The third type of noise is flicker of 1/f noise. The source of 1/f noise is

not well understood but seems to be attributable to manufacturing

noise mechanisms. Its equation is as follows:

1. Independent of frequency and contains a constant power density

per unit of bandwidth.

2. Temperature dependent, increasing with increased temperature.

3. Dependent on photocell resistance value.

I_NF

KI_dcBW ⁄ f

Johnson noise is defined by the following equation:

where:

= flicker noise, amps

I_NJ

(4kTBW) ⁄ R

K = a constant that depends on the type of material

and its geometry

where:

I = dc current, amps

BW = bandwidth of interest, Hertz

f = frequency, Hertz

= Johnson noise current, amps RMS

-23

k = Boltzmann’s constant, 1.38 x 10

T = temperature, degrees Kelvin

R = photocell resistance

Unlike thermal or shortnoise, flicker noise has 1/f spectral density and

in the ideal case for which it is exactly proportional to 1 ⁄ f, it is

termed “pink noise”. Unfortunately, the constant (K) can only be

determined empirically and may vary greatly even for similar devices.

Flicker noise may dominate when the bandwidth of interest contains

frequencies less than about 1 kHz.

BW = bandwidth of interest, Hertz

A second type of noise is “shot” noise. When a direct current flows

through a device, these are some random variations superimposed on

this current due to random fluctuations in the emission of electrons due

to photon absorption. The velocity of the electrons and their transit

time will also have an effect.

In most AOI circuits noise is usually so low that it is hardly ever

considered. One notable exception is in applications where large

voltages are placed across the cell. For a typical isolator, it takes 80 to

100V across the photocell before the noise level starts to increase

significantly.

“Shot” noise is:

1. Independent of frequency.

2. Dependent upon the direct current flowing through the photocell.

Distortion

Shot noise is defined by the following equation:

Analog Optical Isolators have found wide use as control elements in

audio circuits because they possess two characteristics which no other

active semiconductor device has: resistance output and low harmonic

distortion. AOIs often exhibit distortion levels below -80 db when the

voltage applied to the photocell output is kept below 0.5V.

I_NS

2eI_dcBW

where:

= shot noise current, amps RMS

Figure 3 shows the typical distortion generated in typical AOIs. The

distortion depends on the operating resistance level as well as the

applied voltage. The minimum distortion or threshold distortion shown

in Figure 3 is a second harmonic of the fundamental frequency. The

actual source of this distortion is unknown, but may be due to some

type of crossover nonlinearity at the original of the I-V curve of the

photocell.

-19

e = electron charge, 1.6 x 10

I = dc current, amps

BW = bandwidth of interest, Hertz

Characteristics of Analog Optical Isolators

(a)

(b)

(c)

(d)

Figure 3. Typical LED AOI Distortion Characteristics

At high AC voltages, distortion to the waveform can be seen using an

oscilloscope. The waveform is still symmetrical but contains the

fundamental and the odd harmonics, the third harmonic being

predominant. If there is DC as well as AC voltage on the photocell,

both even and odd harmonics are generated.

The RMS value of voltage or current is not very sensitive to a large

third harmonic component, but the instantaneous value is. A 10%

harmonic will only change the RMS values by 0.5%. If the output is

used to control a thermal element, such as a thermal relay, circuit

operation is not affected. Further, when the AOI is used in ON-OFF

applications, waveform distortion is not a problem.

Characteristics of Analog Optical Isolators

Voltage Rating

Power Rating

The maximum voltage rating of the output element (photocell) applies

only when the input is off. Two different kinds of dark current “leakage”

characteristics are observed in photocell output elements. Figure 4

shows the soft breakdown found in lower resistivity materials. With no

Photocells are primarily used for signal control since the maximum

allowable power dissipation is low. Typically, the steady-state output

current should be kept below 10 mA on catalog LED AOIs because of

the small size ceramic used in the output cell. However, the surface

area is large compared to similarly rated transistors, so AOIs withstand

significant transient current and power surges.

input, if the applied voltage is suddenly increased from zero to V , the

current increases along section ‘a’, with the steepness depending on

the rate at which the voltage is increased. If the voltage is now held at

V1, the current decreases along curve ‘b’ and stabilizes at a much

lower value. If the voltage is again increased, the next section of the

curve is traversed with the current dropping along curve ‘d’ in time.

This process can be repeated until the reverse current becomes so

great that the cell burns up. The maximum voltage rating for photocells

with this soft reverse characteristic is based on a safe steady-state

power dissipation in the OFF condition.

Power ratings are given in the catalog and are typically a few hundred

milliwatts, but special AOIs have been made with power dissipation

ratings as high as 2.0 W.

Life and Aging

Life expectancy of an AOI is influenced both by the input and output

devices. Isolators which use an LED have long life since LED lifetimes

are long: 10,000 to 200,000 hours, depending on the application. LEDs

normally show a decrease in light output for a specified bias current as

they age.

The photocell output elements in AOIs show an increase in output

resistance over time as they age. With a continuous input drive current

and with voltage bias applied to the output, the output resistance will

generally increase at a rate of 10 percent per year. The aging rate is

lower with intermittent operation. Figure 5 shows the trend line for

output resistance under typical operating conditions. Other AOIs using

different photoconductive materials show similar trends.

Figure 4. Breakdown characteristics of photocells with low resistivity

photoconductive material.

Higher resistivity photoconductive materials do not show the reverse

characteristics of Figure 4 to any significant degree. As voltage is

increased, the dark current increases, but remains very low until

breakdown occurs. The current then increases in an avalanche fashion

resulting in an arc-over which causes the cell to be permanently

damaged (shorted). The dielectric breakdown voltage is approximately

8 - 10 kV per cm of contact spacing for materials with this type of

reverse characteristic. Photocells have 0.16 - 0.5 mm electrode

spacing so the maximum voltage ratings typically fall into the 100 - 300

volt range.

Figure 5. VTL5C3 Life Test.

The high voltage capability of photocells suggests their use as the

series pass element in a high voltage regulated power supply. Voltages

up to 5 or 10 kV can be regulated but the current should be limited to 1

or 2 mA. The isolated input element greatly simplifies the circuit design

and the single output element avoids the need for voltage and current

sharing components.

Characteristics of Analog Optical Isolators

Storage at low temperature has no operating effect on AOIs. Units may

Storage Characteristics

be stored at temperatures as low as -40°C. Lower temperatures may

cause mechanical stress damage in the package which can cause

permanent changes in the AOI transfer characteristics.

The instantaneous output resistance of any AOI is somewhat

dependent on the short term light history of the photocell output

element. With no applied input current or voltage, the output element is

in the dark. Dark storage causes the cell to “dark adapt”, a condition

which results in an increase in the photocell’s sensitivity to light. When

first turned on, an AOI which has experienced a period of dark

adaption will exhibit a lower value for “on” resistance, at any given drive

condition, than the same device which has been continuously on.

The chemistry of the photoconductive materials dictates a maximum

operating and storage temperature of 75°C. It should be noted that

operation of the photocell above 75°C does not usually lead to

catastrophic failure but the photoconductive surface may be damaged,

leading to irreversible changes in sensitivity.

The amount of resistance change is a function of time as well as

temperature. While changes of several hundred percent will occur in a

matter of a few minutes at 150°C, it will take years at 50°C to produce

that much change.

The output resistance of an AOI which has been biased “on” is

considered to be constant with time (neglecting long term aging

effects). After the removal of the input drive, the photocell begins to

experience dark adaption. The cell’s rate of increase in sensitivity is

initially high but eventually levels off with time in an exponential

manner. Most of the dark adapt occurs in the first eight hours, but with

some AOIs for sensitivity can continue to increase for several weeks.

When an AOI which has been sitting in the dark is turned on, the cell

immediately begins returning to its light adapted state. For any given

device, the rate of recovery is dependent on the input light level.

In most applications, operation is intermittent. At elevated

temperatures, the resistance of the cell rises during the turn-on period

and recovers during the turn-off period, usually resulting in little net

change. However, if the AOI is stored at elevated temperatures for

many hours with no input signal, there is a net reduction in output

resistance. There will be some recovery during operation over time but

it is not possible to predict the rate or to what degree. Elevated

temperatures do not produce sudden catastrophic failure, but changes

in the device transfer curve with time must be anticipated.

The type of photoconductive material is the major factor determining

the magnitude of these changes. Lower resistivity materials show

greater initial and final changes but their rate of change is faster.

These light/dark history effects are pronounced at both high and low

input levels. However, at high input levels, the photocell light adapts

quite rapidly, usually in minutes.

Figure 1 shows the transfer curves for an AOI after 24 hour storage

with no input and then after it has been operated with rated input for 24

hours. Because of these “memory” phenomena, it is best to use these

parts in a closed loop circuit to minimize the effects of these changes.

Open loop proportional operation is possible if the application can

tolerate variations. The use of the VTL5C2 and VTL5C3 with their

more stable characteristics will help.

Temperature Range

Operating and storage temperature range is limited at the lower end by

the reduction of dark resistance of the cell and at the upper end by

rapid aging. At low temperatures, the response time of the output cell

increases. The temperature at which this becomes pronounced

depends on the photoconductive material type. Isolators using low

resistivity materials, as in the VTL5C4, will show this lengthening of

response time at -25°C. Higher resistivity materials such as used in the

VTL5C3 and VTL5C6 do not slow down excessively until temperatures

get below -40°C. This characteristic is completely reversible with the

response time recovering when the temperature rises.

Characteristics of Analog Optical Isolators

Capacitance

The equivalent circuit for the output photocell is a resistor in parallel

with the capacitance. The capacitance arises from the topside

metallization of the electrodes which form a coplanar capacitor. The

value of this capacitance is largely determined by the size of the

ceramic base. For lower capacitance, a smaller cell is needed. The

capacitance is so small (3.0 pF, typical on catalog AOIs) that it is

negligible in most applications. However, there are applications such

as wideband or high frequency amplifiers in which the capacitance

needs to be considered. At 4.5 MHz, the video baseband frequency,

the photocell capacitive reactance is only 12 kilohms. If the phase shift

of the signal is to be kept below 10°, the highest useful cell resistance

is only 2.0 kilohms. At high AOI input drive, where the cell is drive

below 1.0 kilohm, the capacitance can increase additionally from 2 to

10 times, possibly due to distributed effects.

Summary

Analog Optical Isolators have many unique features, such as:

1. High input-to-output isolation.

2. True resistance element output.

3. Wide dynamic range (low “on” resistance/high “off” resistance).

4. Low drive current.

5. Low distortion.

These features are primarily dependent on which input element and

output element photoconductive material is used in the Vactrol AOI.

Thus, there is a wide variety of Vactrols to choose from for your

application.

Characteristics of Analog Optical Isolators

Typical Transfer Characteristics (Resistance vs. Input Current) For Standard Vactrols

Curves shown are based upon a light adapt condition for 24 hours @ no input at 25°C.

Output Resistance vs. Input Current

VTL5C Series

Output Resistance vs. Input Current

VTL5C Series

Characteristics of Analog Optical Isolators

Analog Optoisolator Comparison Chart

Temperature

Coefficient

Speed of

Response

Light History

Effect

Device

Material Type

Slope

Dynamic Range Dark Resistance

VTL5C1

VTL5C2

VTL5C2/2

VTL5C3

VTL5C3/2

VTL5C4

VTL5C4/2

VTL5C6

VTL5C7

VTL5C8

VTL5C9

VTL5C10

15.0

24.0

20.0

19.0

18.7

8.3

100 db

69 db

65 db

75 db

71 db

72 db

68 db

88 db

75 db

80 db

112 db

75 db

50 MΩ

1 MΩ

Very High

Low

Very Fast

Slow

Very Large

Small

1 MΩ

Low

Slow

Small

10 MΩ

400 MΩ

100 MΩ

1 MΩ

Very Low

High

Very Slow

Fast

Very Small

Large

High

Fast

Large

16.7

5.7

Low

Slow

Small

Average

Low

Average

Slow

Average

Small

8.0

10 MΩ

50 MΩ

400 MΩ

7.3

Very High

High

Very Fast

Fast

Very Large

Large

3.8

Specification Notes

(These notes are referenced on the following LED Vactrol Data Sheet pages.)

Since the input has a substantially constant voltage drop, a current limiting resistance is required.

Dark adapted resistance measured after 24 or more hours of no input.

Measured 10 sec. after removal of the input. The ultimate resistance is many times greater than the value at 10 seconds.

Ascent measured to 63% of final conductance from the application of 40 mA input. The conductance rise time to a specified value is

increased at reduced input drive while the conductance decay time to a specified value is decreased.

Typical matching and tracking from 0.4 to 40 mA is 25%.

Measured 5 sec. after removal of the input. The ultimate resistance is many times greater than the value at 5 seconds.

VTL5C9 response times are based on a 2.0 mA input. VTL5C10 response times are based on a 10.0 mA input for ascent time and

a 1.0 mA input for decay time.

Low Cost Axial Vactrols

VTL5C1, 5C2

PACKAGE DIMENSIONS inch (mm)

PLASTIC POTTING CONTOUR

NOT CONTROLLED

DESCRIPTION

VTL5C1 offers 100db dynamic range, fast response time, and very high dark resistance.

VTL5C2 features a very steep slope, low temperature coefficient of resistance, and a small light history memory.

ABSOLUTE MAXIMUM RATINGS @ 25°C

LED Forward Voltage Drop @ 20 mA:

2.0V (1.65V Typ.)

Maximum Temperatures

Storage and Operating:

Cell Power:

–40°C to 75°C

175 mW

Min. Isolation Voltage @ 70% Rel. Humidity: 2500 VRMS

Derate above 30°C:

LED Current:

3.9 mW/°C

Output Cell Capacitance:

Cell Voltage:

5.0 pF

40 mA

Derate above 30°C:

0.9 mA/°C

100V (VTL5C1),

200V (VTL5C2)

0.5 pF

LED Reverse Breakdown Voltage:

3.0 V

Input - Output Coupling Capacitance:

ELECTRO-OPTICAL CHARCTERISTICS @ 25°C

Response Time

ON Resistance

Slope

(Typ.)

Dynamic Range

(Typ.)

OFF

Part

Number

Material

Type

Dark

Input current Adapted

(Typ.)

Turn-on to

Turn-off (Decay)

to 100 kΩ

(Max.)

Resistance

@ 10 sec. (Min.)

63% Final R

@ 0.5 mA

------------------------

R@ 5 mA

DARK

-----------------------

(Typ.)

R@ 20 mA

1 mA

10 mA

40 mA

20 kΩ

600 Ω

200 Ω

VTL5C1

VTL5C2

50 MΩ

1 MΩ

100 db

69 db

2.5 ms

35 ms

1 mA

10 mA

40 mA

5.5 kΩ

800 Ω

200 Ω

3.5 ms

500 ms

Refer to Specification Notes, page 41.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

Typical Performance Curves

Output Resistance vs. Input Current

VTL5C1

Response Time

VTL5C1

Output Resistance vs. Input Current

VTL5C2

Response Time

VTL5C2

Input Characteristics

Notes:

1. At 1.0 mA and below, units may have substantially higher

resistance than shown in the typical curves. Consult factory if

closely controlled characteristics are required at low input

currents.

2. Output resistance vs input current transfer curves are given for

the following light adapt conditions:

(1)

(2)

(3)

(4)

25°C — 24 hours @ no input

25°C — 24 hours @ 40 mA input

+50°C — 24 hours @ 40 mA input

–20°C — 24 hours @ 40 mA input

3. Response time characteristics are based upon test following

adapt condition (2) above.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

Low Cost Axial Vactrols

VTL5C3, 5C4

PACKAGE DIMENSIONS INCH (MM)

PLASTIC POTTING CONTOUR

NOT CONTROLLED

DESCRIPTION

VTL5C3 has a steep slope, good dynamic range, a very low temperature coefficient of resistance, and a small light history memory.

VTL5C4 features a very low “on” resistance, fast response time, with a smaller temperature coefficient of resistance than VTL5C1.

ABSOLUTE MAXIMUM RATINGS @ 25°C

LED Forward Voltage Drop @ 20 mA:

2.0V (1.65V Typ.)

Maximum Temperatures

Storage and Operating:

Cell Power:

–40°C to 75°C

175 mW

Min. Isolation Voltage @ 70% Rel. Humidity: 2500 VRMS

Derate above 30°C:

LED Current:

3.9 mW/°C

Output Cell Capacitance:

Cell Voltage:

5.0 pF

40 mA

Derate above 30°C:

0.9 mA/°C

250V (VTL5C3),

50V (VTL5C4)

0.5 pF

LED Reverse Breakdown Voltage:

3.0 V

Input - Output Coupling Capacitance:

ELECTRO-OPTICAL CHARCTERISTICS @ 25°C

Response Time

ON Resistance

Dynamic Range

(Typ.)

Slope

(Typ.)

OFF 3

Resistance

@ 10 sec. (Min.)

Part

Number

Material

Type

Dark

Input current Adapted

(Typ.)

Turn-on to

Turn-off (Decay)

to 100 kΩ

(Max.)

R@ 0.5 mA

-------------------------

R@ 5 mA

63% Final R

DARK

-----------------------

(Typ.)

R@ 20 mA

1 mA

10 mA

40 mA

30 kΩ

5 Ω

1.5 Ω

VTL5C3

VTL5C4

10 MΩ

75 db

72 db

2.5 ms

35 ms

1 mA

10 mA

40 mA

1.2 kΩ

125 Ω

75 Ω

400 MΩ

18.7

6.0 ms

1.5 sec

Refer to Specification Notes, page 41.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

Typical Performance Curves

Output Resistance vs. Input Current

VTL5C3

Response Time

VTL5C3

Output Resistance vs. Input Current

VTL5C4

Response Time

VTL5C4

Input Characteristics

Notes:

1. At 1.0 mA and below, units may have substantially higher

resistance than shown in the typical curves. Consult factory if

closely controlled characteristics are required at low input

currents.

2. Output resistance vs input current transfer curves are given for

the following light adapt conditions:

(1)

(2)

(3)

(4)

25°C — 24 hours @ no input

25°C — 24 hours @ 40 mA input

+50°C — 24 hours @ 40 mA input

–20°C — 24 hours @ 40 mA input

3. Response time characteristics are based upon test following

adapt condition (2) above.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

Dual Element Axial Vactrols

VTL5C2/2, 5C3/2

PACKAGE DIMENSIONS INCH (MM)

PLASTIC POTTING CONTOUR

NOT CONTROLLED

DESCRIPTION

VTL5C2/2 features a very steep slope, low temperature coefficient of resistance, and a small light history memory.

VTL5C3/2 has a steep slope, good dynamic range, a very low temperature coefficient of resistance, and a small light history memory.

ABSOLUTE MAXIMUM RATINGS @ 25°C

LED Forward Voltage Drop @ 20 mA:

2.0V (1.65V Typ.)

Maximum Temperatures

Storage and Operating:

Cell Power:

–40°C to 75°C

175 mW

Min. Isolation Voltage @ 70% Rel. Humidity: 2500 VRMS

Derate above 30°C:

LED Current:

3.9 mW/°C

Output Cell Capacitance:

Cell Voltage:

5.0 pF

40 mA

Derate above 30°C:

0.9 mA/°C

50V (VTL5C2/2),

100V (VTL5C2/3)

0.5 pF

LED Reverse Breakdown Voltage:

3.0 V

Input - Output Coupling Capacitance:

ELECTRO-OPTICAL CHARCTERISTICS @ 25°C

Response Time

ON Resistance

Dynamic Range

(Typ.)

Slope

(Typ.)

OFF

Part

Number

Material

Type

Dark

Input current Adapted

(Typ.)

Turn-on to

Turn-off (Decay)

to 100 kΩ

(Max.)

Resistance

@ 10 sec. (Min.)

63% Final R

DARK

@ 0.5 mA

------------------------

R@ 5 mA

-----------------------

(Typ.)

R@ 20 mA

5 mA

40 mA

2.5 kΩ

700 Ω

VTL5C2/2

VTL5C3/2

1.0 MΩ

10 MΩ

65 db

71 db

7.0 ms

150 ms

50 ms

1 mA

40 mA

55 kΩ

2 Ω

3.0 ms

Refer to Specification Notes, page 41.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

Typical Performance Curves

Output Resistance vs. Input Current

VTL5C2/2

Response Time

VTL5C2/2

Output Resistance vs. Input Current

VTL5C3/2

Response Time

VTL5C3/2

Notes:

Input Characteristics

1. At 1.0 mA and below, units may have substantially higher

resistance than shown in the typical curves. Consult factory if

closely controlled characteristics are required at low input

currents.

2. Output resistance vs input current transfer curves are given for

the following light adapt conditions:

(1)

(2)

(3)

(4)

25°C — 24 hours @ no input

25°C — 24 hours @ 40 mA input

+50°C — 24 hours @ 40 mA input

–20°C — 24 hours @ 40 mA input

3. Response time characteristics are based upon test following

adapt condition (2) above.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

Dual Element Axial Vactrols

VTL5C4/2

PACKAGE DIMENSIONS INCH (MM)

PLASTIC POTTING CONTOUR

NOT CONTROLLED

DESCRIPTION

VTL5C4/2 features a very low “on” resistance, fast response time, with a smaller temperature coefficient of resistance than VTL5C1.

ABSOLUTE MAXIMUM RATINGS @ 25°C

LED Forward Voltage Drop @ 20 mA:

2.0V (1.65V Typ.)

Maximum Temperatures

Storage and Operating:

Cell Power:

–40°C to 75°C

175 mW

Min. Isolation Voltage @ 70% Rel. Humidity: 2500 VRMS

Derate above 30°C:

LED Current:

3.9 mW/°C

Output Cell Capacitance:

Cell Voltage:

5.0 pF

30V

40 mA

Derate above 30°C:

0.9 mA/°C

LED Reverse Breakdown Voltage:

3.0 V

Input - Output Coupling Capacitance:

0.5 pF

ELECTRO-OPTICAL CHARCTERISTICS @ 25°C

ON Resistance

Dynamic Range

(Typ.)

Response Time

Slope

(Typ.)

OFF

Part

Number

Material

Type

Dark

Input current Adapted

(Typ.)

Turn-on to

Turn-off (Decay)

to 100 kΩ

(Max.)

Resistance

@ 10 sec. (Min.)

63% Final R

DARK

@ 0.5 mA

------------------------

R@ 5 mA

-----------------------

(Typ.)

R@ 20 mA

1 mA

10 mA

1.5 kΩ

150 Ω

VTL5C4/2

400 Ω

8.3

68 db

6.0 ms

1.5 sec

Refer to Specification Notes, page 41.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

Typical Performance Curves (Per Element)

Output Resistance vs. Input Current

VTL5C4/2

Response Time

VTL5C4/2

Notes:

Input Characteristics

1. At 1.0 mA and below, units may have substantially higher

resistance than shown in the typical curves. Consult factory if

closely controlled characteristics are required at low input

currents.

2. Output resistance vs input current transfer curves are given for

the following light adapt conditions:

(1)

(2)

(3)

(4)

25°C — 24 hours @ no input

25°C — 24 hours @ 40 mA input

+50°C — 24 hours @ 40 mA input

–20°C — 24 hours @ 40 mA input

3. Response time characteristics are based upon test following

adapt condition (2) above.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

Low Cost Axial Vactrols

VTL5C6, 5C7

PACKAGE DIMENSIONS INCH (MM)

PLASTIC POTTING CONTOUR

NOT CONTROLLED

DESCRIPTION

VTL5C6 has a large dynamic range, high dark resistance, a low temperature coeffecient of resistance, and a small light history

memory. VTL5C7 is a shallow sloped device with good dynamic range, average temperature coefficient of resistance, speed of

response, and light history memory.

ABSOLUTE MAXIMUM RATINGS @ 25°C

LED Forward Voltage Drop @ 20 mA:

2.0V (1.65V Typ.)

Maximum Temperatures

Storage and Operating:

Cell Power:

–40°C to 75°C

175 mW

Min. Isolation Voltage @ 70% Rel. Humidity: 2500 VRMS

Derate above 30°C:

LED Current:

3.9 mW/°C

Output Cell Capacitance:

Cell Voltage:

5.0 pF

40 mA

Derate above 30°C:

0.9 mA/°C

250V (VTL5C6),

50V (VTL5C7)

0.5 pF

LED Reverse Breakdown Voltage:

3.0 V

Input - Output Coupling Capacitance:

ELECTRO-OPTICAL CHARCTERISTICS @ 25°C

Response Time

ON Resistance

DynamicRange

Slope

(Typ.)

OFF

Part

Number

Material

Type

Turn-off (Decay)

to (Max.)

Dark

Adapted

(Typ.)

Turn-on to

Resistance

@ 10 sec. (Min.)

Input

current

63% Final R

@ 0.5 mA

------------------------

R@ 5 mA

DARK

-----------------------

(Typ.)

3.5 ms

6.0 ms

1 MΩ

100 kΩ

R@ 20 mA

1 mA

10 mA

40 mA

75 kΩ

10 kΩ

2 kΩ

VTL5C6

VTL5C7

100 MΩ

1 MΩ

16.7

5.7

88 db

75 db

50 ms

0.4 mA

2 mA

5 kΩ

1.1 kΩ

1 sec

Refer to Specification Notes, page 41.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

Typical Performance Curves

Output Resistance vs. Input Current

VTL5C6

Response Time

VTL5C6

Output Resistance vs. Input Current

VTL5C7

Response Time

VTL5C7

Input Characteristics

Notes:

1. At 1.0 mA and below, units may have substantially higher

resistance than shown in the typical curves. Consult factory if

closely controlled characteristics are required at low input

currents.

2. Output resistance vs input current transfer curves are given for

the following light adapt conditions:

(1)

(2)

(3)

(4)

25°C — 24 hours @ no input

25°C — 24 hours @ 40 mA input

+50°C — 24 hours @ 40 mA input

–20°C — 24 hours @ 40 mA input

3. Response time characteristics are based upon test following

adapt condition (2) above.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

Low Cost Axial Vactrols

VTL5C8

PACKAGE DIMENSIONS INCH (MM)

PLASTIC POTTING CONTOUR

NOT CONTROLLED

DESCRIPTION

VTL5C8 is similar to VTL5C2 with a low temperature coefficient of resistance and little light history memory, but has a more shallow

slope and a lower “on” resistance at low (1 mA) drive currents.

ABSOLUTE MAXIMUM RATINGS @ 25°C

LED Forward Voltage Drop @ 20 mA:

2.8V (2.2V Typ.)

Maximum Temperatures

Storage and Operating:

Cell Power:

–40°C to 75°C

175 mW

Min. Isolation Voltage @ 70% Rel. Humidity: 2500 VRMS

Derate above 30°C:

LED Current:

3.9 mW/°C

Output Cell Capacitance:

Cell Voltage:

5.0 pF

500V

0.5 pF

40 mA

Derate above 30°C:

0.9 mA/°C

LED Reverse Breakdown Voltage:

3.0 V

Input - Output Coupling Capacitance:

ELECTRO-OPTICAL CHARCTERISTICS @ 25°C

ON Resistance

Dynamic Range

(Typ.)

Response Time

Slope

(Typ.)

OFF

Part

Number

Material

Type

Dark

Input current Adapted

(Typ.)

Turn-on to

Turn-off (Decay)

to 100 kΩ

(Max.)

Resistance

@ 10 sec. (Min.)

63% Final R

@ 0.5 mA

------------------------

R@ 5 mA

DARK

-----------------------

(Typ.)

R@ 20 mA

1 mA

4 mA

16 mA

4.8 kΩ

1.8 kΩ

1.0 kΩ

VTL5C8

10 MΩ

80 db

4 ms

60 ms

Refer to Specification Notes, page 41.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

Typical Performance Curves

Output Resistance vs. Input Current

VTL5C8

Response Time

VTL5C8

Input Characteristics

Notes:

1. At 1.0 mA and below, units may have substantially higher

resistance than shown in the typical curves. Consult factory if

closely controlled characteristics are required at low input

currents.

2. Output resistance vs input current transfer curves are given for

the following light adapt conditions:

(1)

(2)

(3)

(4)

25°C — 24 hours @ no input

25°C — 24 hours @ 40 mA input

+50°C — 24 hours @ 40 mA input

–20°C — 24 hours @ 40 mA input

3. Response time characteristics are based upon test following

adapt condition (2) above.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

Low Cost Axial Vactrols

VTL5C9, 5C10

PACKAGE DIMENSIONS INCH (MM)

PLASTIC POTTING CONTOUR

NOT CONTROLLED

DESCRIPTION

VTL5C9 has a 112 db dynamic range, fast response time, high dark resistance, but with a more shallow slope and lower “on”

resistance at low (1 mA) drive currents than the VTL5C1. VTL510 offers a low “on” resistance at low drive currents, a fast response

time, and has a smaller temperature coefficient than the VTL5C9.

ABSOLUTE MAXIMUM RATINGS @ 25°C

LED Forward Voltage Drop @ 20 mA:

2.8V (2.2V Typ.)

Maximum Temperatures

Storage and Operating:

Cell Power:

–40°C to 75°C

175 mW

Min. Isolation Voltage @ 70% Rel. Humidity: 2500 VRMS

Derate above 30°C:

LED Current:

3.9 mW/°C

Output Cell Capacitance:

Cell Voltage:

5.0 pF

40 mA

Derate above 30°C:

0.9 mA/°C

100V (VTL5C9),

50V (VTL5C10)

0.5 pF

LED Reverse Breakdown Voltage:

3.0 V

Input - Output Coupling Capacitance:

ELECTRO-OPTICAL CHARCTERISTICS @ 25°C

Response Time

ON Resistance

Dynamic Range

(Typ.)

Slope

(Typ.)

OFF

Part

Number

Material

Type

Dark

Input current Adapted

(Typ.)

Turn-on to

Turn-off (Decay)

to 100 kΩ

(Max.)

Resistance

@ 10 sec. (Min.)

63% Final R

@ 0.5 mA

------------------------

R@ 5 mA

DARK

-----------------------

(Typ.)

R@ 20 mA

VTL5C9

2 mA

630 Ω

400 Ω

50 MΩ

7.3

112 db

4.0 ms

1.0 ms

50 ms

VTL5C10

400 KΩ

3.8

75 db

1.5 sec

Refer to Specification Notes, page 41.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

Typical Performance Curves

Output Resistance vs. Input Current

VTL5C9

Response Time

VTL5C9

Output Resistance vs. Input Current

VTL5C10

Response Time

VTL5C10

Input Characteristics

Notes:

1. At 1.0 mA and below, units may have substantially higher

resistance than shown in the typical curves. Consult factory if

closely controlled characteristics are required at low input

currents.

2. Output resistance vs input current transfer curves are given for

the following light adapt conditions:

(1)

(2)

(3)

(4)

25°C — 24 hours @ no input

25°C — 24 hours @ 40 mA input

+50°C — 24 hours @ 40 mA input

–20°C — 24 hours @ 40 mA input

3. Response time characteristics are based upon test following

adapt condition (2) above.

PerkinElmer Optoelectronics, 10900 Page Ave., St. Louis, MO 63132 USA

Phone: 314-423-4900 Fax: 314-423-3956 Web: www.perkinelmer.com/opto

Application Notes—Analog Optical Isolators

resistor, the feedback may approach an open circuit condition at

maximum gain. In this open loop state, the circuit becomes unstable

and may latch up. The parallel resistor R sets the maximum gain of

APPLICATION NOTE #1 Audio Applications

The LDR output element of AOIs is almost purely resistive in nature.

This property makes the AOI a very useful device for the control of AC

signals. Further, because AOIs also possess very low noise and low

harmonic distortion characteristics, they are ideal for use as variable

resistors, capable of being remotely adjusted in a wide range of audio

applications and control circuits.

the amplifier and stabilizes the DC output voltage. Resistor R is in

series with the AOI output and sets the minimum gain of the circuit. For

op-amps with unity gain compensation, R is set equal to R so the

circuit gain does not drop below one. The maximum voltage on the cell

(LDR) is e . If minimizing distortion is a consideration, e should be

out

kept below 1.0V.

The focus of this note is on the use of AOIs in audio applications.

However, many of the approaches used are equally applicable to

higher frequency AC amplification and control circuits.

Op-Amp Input Resistor Control

When the AOI is used as the input resistor of an op-amp, Figure 1d, a

fixed resistor in series will limit the maximum gain as well as prevent

overload of the previous stage.

Control Circuits

Voltage Divider Circuits

Non-Inverting Op-Amp Circuits

The output element of the AOI is a two terminal variable resistor and

may be used in a voltage divider circuit as shown in Figures 1a and 1b.

The AOI can also be used in non-inverting op-amp circuits. Gain is

controlled potentiometrically and, again, resistors should be used to

limit the maximum gain. The circuit of Figure 1e requires a resistor in

series with the AOI, while the circuit of Figure 1f requires one in

parallel.

Shunt Input Control

Figure 1a shows the AOI as the shunt element. With I = 0, the

photocell has a very high resistance so e = e . When I is injected

into the LED, the AOI output resistance decreases pulling down the

output voltage. Since the cell cannot be driven to zero resistance, the

out

General Considerations

The circuit application and AOI characteristics will influence the choice

of circuit to use. In Figure 1a to 1f, gain vs. I curves are given for each

value of R must be selected to give the desired maximum attenuation.

circuit, as well as input impedance and gain formulas. Once the proper

circuit function is selected, AOI response speed must be considered.

Because an LDR (photocell) turns “on” fast and “off” slowly, circuits of

Figure 1d and 1e will increase in gain rapidly but be slower in the

decreasing gain. The circuits of Figure 1c and 1f respond faster when

the gain is reduced. All other design considerations are the same as

they would be for any op-amp circuit. In all the amplifier configurations,

a gain ratio of 1000:1 or higher can be achieved.

A VTL5C4 with a maximum “on” resistance of 200 ohms at I = 10 mA

requires an R of 6100 ohms for 30 db voltage attenuation (producing

a 1000:1 power ratio). The actual attenuation ratio will be greater since

the 10 mA “on” resistance is typically 125 ohms.

When the maximum I is less than 10 mA, the series resistance must

be greater to get the same attenuation ratio. If R is made large, the

insertion loss (db attenuation at I = 0) will be higher when the output is

loaded. The maximum voltage across the photocell in this circuit is

equal to the input voltage assuming no insertion loss. An input voltage

as high as 5 – 10V will produce noticeable distortion but that will drop

as I is increased. To minimize distortion, the voltage across the cell

should be kept below 1.0V at the normal operating point.

Series Input Control

With an AOI as the series element as shown in Figure 1b, e =0 at I

out

= 0. The maximum voltage across the cell is e , but decreases as I

increases.

Op-Amp Feedback Resistor Control

The AOI may also be used as the input or feedback resistor of an

operational amplifier. When used in the feedback loop, Figure 1c, a

fixed resistor should be used in parallel. With no parallel limiting

-------------------------

--------------------------

Application Notes—Analog Optical Isolators

Input

Basic Circuit Configuration

out

----------

Gain

Resistance

R_(LDR)

Variable

R₁+ R_(LDR)

Figure 1a. Shunt Input Control

R₁

Variable

R₁+ R_(LDR)

Figure 1b. Series Input Control

R₃[R_LDR+ R₂]

-------------------------------------------

₁[R_LDR+ R₂+ R₃]

Fixed, Low

Figure 1c. Feedback Resistor Control

Application Notes—Analog Optical Isolators

Basic Circuit Configuration

Input Resistance

Gain

R₂

Variable

-------------------------

R_(LDR)+ R₁

Figure 1d. Input Resistor Control

R₁

1 + --------------------------

R_(LDR)+ R₂

Fixed, High

Figure 1e. Potentiometric Gain

R₁R_(LDR)

+ -------------------------------------

R₂[R_(LDR)+ R₁

Fixed, High

Figure 1f. Potentiometric Gain

Application Notes—Analog Optical Isolators

0.5 db of full signal is one time constant, which is usually only a few

Switching

milliseconds. The step change of a switch has been transformed into a

rapid but smooth increase in signal level. In addition, the possibility of

turn-on in the middle of a peak has been eliminated.

Mechanical switching of low level audio signals requires the use of

switches with precious metal contacts. Sudden changes in signal can

cause the speakers to thump and damage may occur if the speaker is

underdamped. A simple way to avoid these problems is to use an AOI

in place of a mechanical switch. In the circuit of Figure 1d, the initial

resistance of the LDR cell is so high that amplifier gain is essentially

zero. A step change in forward current through the LED is translated

into a slower time change in the cell resistance. The resistance drops

to 10 times the final value in one millisecond or less. As the resistance

continues to drop, the final value is approached exponentially. Express

in terms of conductivity:

Turn-off is slower and depends on the ratio of R1 to the final value of

photocell resistance. A high ratio will slow down the turn-off and speed

up the turn-on.

This circuit can be extended into a matrix as shown in Figure 2. While

a 3 x 3 matrix is shown, the number of nodes is not limited. Individual

inputs can be summed into a single output or connected to more than

one output. A matrix can be made very compact with the output

amplifiers mounted very close to reduce pickup. The op-amps

eliminate any crosstalk between the inputs since the summing point is

at virtual ground.

G = G₀[1 – exp(–t ⁄ tc)] mhos

and:

R = 1 ⁄ G ohms

The controls for the matrix are usually remotely located. The DC

current through the LEDs may be controlled by switches, manual

potentiometers, or a computer. The matrix may be used for simple ON-

OFF gating, summing of several signals, or proportional control. When

proportional control is used, the output should be continuously

supervised to correct for changes in signal level due to photocell

resistance variation from temperature, light adapt history, and self

heating.

where:

G = conductance, mhos

t = time, ms

tc = time constance of the photocell, ms

If R1 is made equal to nine times the final value of resistance, the

response to 50% signal will occur in 1.0 ms. The time to get to within

Figure 2. Switching Matrix

Application Notes—Analog Optical Isolators

A which inverts the negative half of the signal. The rectifier charges

Gating and Muting

C used for RELEASE TIME control and drives the base of transistor

Background noise becomes very objectionable when a signal level in a

program is low. Noise is any unwanted sound and may be due to tape

hiss or amplifier hum. These noises can be eliminated by selective use

of gating and muting, that is, turning the amplifier on when the signal

level is high and off when it is low. This technique can also remove or

reduce unwanted echo, print through, presence or any other distracting

signal during portions of a program which are normally silent. The

gating circuit must be completely transparent to the listener, having a

smooth, rapid operation with no signal distortion.

Q , the LED driver. The threshold voltage is a sum of the forward drop

of the rectifying diodes, the voltage drop across R , V or Q and V

of the LED. This voltage is 2.5 – 3.0V and when referred to the input

gives a threshold of 2.5 – 3.0 mV at the amplifier.

The circuit can be set up for a specified threshold voltage. Release

time is usually determined empirically. A typical set up procedure uses

an audio signal containing spoken dialog. Initially, the THRESHOLD

adjustment is set to the maximum and the RELEASE is set to the

minimum. The program is turned on and the THRESHOLD is

decreased until the audio starts coming through, but sounds chopped

up. The chopping occurs because the circuit is too fast on release. The

RELEASE is increased until the audio is smoothed out and sounds

normal. Setting of the two controls needs to be made carefully. A

threshold set too high cuts off the quieter sounds, while a setting which

is too low allows more of the noise to come through. Short release time

causes more chopping of the audio and can create some distortion at

the lower frequencies. Long release time keeps the gate open too long

allowing noise to come through after the signal is gone. Adjustments

should be made incrementally and worked between the two controls

until the best sound is achieved.

A practical gating circuit having these features is shown in Figure 3.

The circuit has five basic sections: the threshold adjustment, a high AC

gain stage, full-wave rectifier, LED driver and an electrically controlled

voltage divider. When the signal is below the threshold level, the

voltage divider consisting of the AOI and R has maximum

attenuation. When the signal exceeds the threshold, the voltage divider

allows the signal to pass through.

The circuit operation is as follows. The THRESHOLD potentiometer

applies a portion of the signal to the high gain AC amplifier consisting

of op-amp A , resistors R and R and capacitor C . The amplified

signal is full-wave rectified by diodes D and D together with op-amp

Figure 3. Audio Sound Gate

Application Notes—Analog Optical Isolators

from going open loop when there is no input signal, in which case the

cell “off” resistance is much higher than 10 M

Limiters

Ω.

If the magnitude of an AC signal varies over a wide range, it may be

necessary to amplify or compress the signal before any audio

processing can be performed. In other cases, the audio power has to

be limited to prevent damage to an output device. Circuits that perform

this function on a continual basis need a non-linear element to produce

variable gain. However, most non-linear elements introduce distortion.

This is unacceptable in a high fidelity audio circuit and other critical

applications. Using an AOI, simple circuits can be made to perform this

function without introducing distortion or generating any noise.

Amplifier A operates as a high input impedance rectifier that drives

the LED. The forward drop of the LED is 1.6 – 2.0V, and when the peak

output of the rectifier exceeds this value, current will flow into the LED.

As the signal increases, more current flows into the LED, driving the

photocell resistance lower thus decreasing the amplifier gain. The

output of A is regulated at a voltage determined by the forward drop of

the LED and the closed loop gain of amplifier A . A amplifies the

signal by a factor of two, and a 1.8V peak (1.27 VRMS) is required to

activate this AOI. This results in the output voltage being held to 0.64

VRMS over a input range of 1 – 600 mV. Changing the value of R

Signal Limiters

changes the gain of the rectifier. Omitting R will double the output

voltage because the rectifier gain drops to one. Putting a resistor in

series with the LED will cause the regulated voltage to rise as the input

is increased (see Figure 4b). As the amplifier gain changes, the

amplifier bandwidth also changes. When the signal is low, the amplifier

will have the highest gain and lowest bandwidth.

Any circuit that performs as a limiter or compressor must have low gain

when the signal magnitude is high and high gain when the signal is

low. The gain is adjusted so that a wide dynamic range is compressed

into a small one. In other signal processing applications, the signal

may need to be virtually constant.

The circuit such as shown in Figure 4a will keep the output level

constant when the input voltage varies over a range of 50 – 60 db.

Amplifier A1 operates as an inverting amplifier with a gain:

/ e = R

/ R

out in

PHOTOCELL 1

The feedback resistor is a photocell and has an “off” resistance of 10

megohms, minimum, and an “on” resistance of 5000 ohms with 5.0 mA

in the LED. Using the components shown, the gain of this stage varies

between 500 with no signal and 0.5 with maximum signal applied. R

limits the maximum gain and is needed to prevent the amplifier, A

Figure 4a. Peak Sensing Compressor

Figure 4b. Output Characteristics

Application Notes—Analog Optical Isolators

Figure 5. Peak Sensing Compressor with Constant Bandwidth

Variable bandwidth can be avoided if the AOI is used in a voltage

divider circuit at the input of a fixed gain amplifier. For the same range

of input signals, the amplifier gain must be 500 and the voltage divider

must have a range of 1000:1. This configuration is shown in Figure 5.

The AOI has been changed to a lower resistance unit to be able to

the voltage limit is determined by the allowable diaphragm excursion.

For constant voltage on the speaker, the displacement doubles when

the frequency is reduced by half. The maximum displacement is

determined by the mechanical design of the speaker and exceeding

the limit will produce extreme distortion and may even cause

mechanical damage.

work over the wider range. Also, A is now a high input impedance,

non-inverting stage to avoid a high insertion loss. This circuit is useful

when the input voltage is high, which allows the use of a lower gain

amplifier.

Speaker Power Limiting

Speakers that are driven from high power amplifiers must be protected

from excess drive. While ordinary program levels may be well within

the rating of the speaker, peaks do occur that can be destructive. The

simplest solution is to use a compressor or limiter. Unfortunately, the

maximum power that may be applied is not constant over the

frequency range. Therefore, the limit must be set to provide protection

at the lowest frequency that is expected.

Figure 7. Maximum sine wave Voltage and Power for a Typical Woofer

To understand the requirements for effective speaker protection, a brief

review of speaker power limitations follows. Figure 7 is a typical

maximum sine wave voltage limit for a low frequency speaker

commonly called a “woofer”. Above 200 Hz, the maximum allowed

voltage or power is constant. The operating temperature at which wire

insulation and coil bonding fail establishes this value. Below 200 Hz,

Application Notes—Analog Optical Isolators

This reduced low frequency power rating can be accommodated by

using a limited circuit which reduces the limit threshold when the

frequency is below 200 Hz. Figure 8a shows a very simple circuit to do

the threshold has been exceeded, current is injected into the LED of

the AOI which attenuates the signal voltage. This voltage divider can

be placed anywhere in the signal path. Once the limiter comes into

play, the system frequency response will no longer be flat, but no

distortion is introduced.

this. At low frequency, the gain of amplifier A is unity. The amplifier

has a 6 db/octave gain roll-off starting at 25 Hz and levels off at 100

Hz. Therefore it will take a signal that is four times as large at 100 Hz

as at 25 Hz before limiting action starts. Breakpoints in the Frequency

vs. Gain curve shown in Figure 8b can be set to match the speaker

Automatic Gain Control

frequency dependent power limit. Also, potentiometer R can be set to

match the power rating and impedance of the speaker.

Automatic gain control (AGC) circuits have electrically programmable

references or set points, but in other respects are the same as limiters

or compressor circuits. Each has a forward gain amplifier and a loop

which controls the gain of that amplifier.

The threshold is set by the sum of V of Q and the forward voltage

drops of D and the LED, approximately 2.8V peak or 2.0 VRMS. Once

Figure 8a. Speaker Power Limiter with Frequency Compensation

Figure 8b. Amplitude vs. Frequency for the Amplifier

Figure 8c. System Voltage Limits

Application Notes—Analog Optical Isolators

Figure 9 shows an AGC circuit which consists of three main elements:

a variable gain amplifier, full-wave active rectifier and a summing

amplifier. The variable gain amplifier consists of op-amp A1 with

potentiometric gain that is controlled by the resistance of the photocell

of the AOI. The gain of this amplifier is:

too wide, the control loop will follow the signal on an instantaneous

basis. The AOI alone is not very fast, but signals with frequencies of 30

– 60 Hz could be distorted if there were no time delay in the integrator.

The AGC circuit operates as follows. When there is no signal, the

negative V

causes A to be at a maximum positive output.

REF

Gain = 1 + R / R

Maximum forward current is injected into the LED, driving the cell to a

PHOTOCELL

low resistance and the gain of A to the maximum where it stays until

there is a signal. A signal at the input terminal is amplified, rectified and

With R = 100k ohms, the minimum gain is one since the cell “off”

resistance is several megohms. The maximum gain in only 100 since

the resistance of a typical VTL5C2 is 1000 ohms at an input current of

5.0 mA. If a range of 40 db (100:1) is not adequate, there are several

algebraically summed with V

at the inverting terminal of the

REF

integrator. The control loop will then act to make the absolute value of

the rectified signal equal to the reference voltage. V may be a fixed

REF

options. R can be increased, the LED drive current for the AOI can be

value or a function of some other parameter.

increased or a lower resistance AOI such as the VTL5C4 can be used.

Electrically Controlled Gain

Amplifier A together with diodes D and D and resistors R , R , and

R form a full-wave rectifier. The amplifier has a gain of one so the

output is equal to the rectified input. There is no offset due to rectifier

forward drops so this circuit will rectify signals all the way down to zero

The gain of an amplifier can be electrically programmed using the

circuit of Figure 10. An AOI with a center tapped photocell is used, one

side in the signal amplifier channel and the other in the control loop.

volts. Since the DC output of A is not referenced to ground, op-amp

The signal amplifier consists of op-amp A , resistors R and R which

A and resistors R , R , R , and R form a fully differential amplifier

set the gain and the input resistor R . The gain of this amplifier is given

which shifts the DC reference to ground.

by:

Op-amp A is used as an integrator. The signal from the full-wave

e_out(R₂+ R₃)

G = -------- = ----------------------

e_inR₂

rectifier is summed with a reference voltage V and integrated. The

REF

time constant of the integrator is selected to limit the bandwidth of the

control loop as well as assure stability of the loop. If the bandwidth is

Figure 9. AGC Circuit with Electrical Setpoint

Application Notes—Analog Optical Isolators

The control loop consists of op-amp A and resistors R and R . This

Note that R and R are the two halves of the cell. These two resistors

1 2

circuit sets the LED current so that:

match within 10% and track over a wide range within 5% so that the

gain is closely set by V when V is fixed.

REF

V_REF(R₁+ R₄)

---------- = ----------------------

V_CR₁

The limits of operation are:

0 < V < V

REF

If we set:

and:

then:

or:

R = R

3 4

and the signal must never be so large that amplifier A saturates when

the gain is at maximum.

R = R

/ e = V / V

out in REF C

This circuit performs a dividing operation with e and V as the

= e (V / V )

out

in REF

numerator and denominator respectively. The accuracy is limited by

the tracking ability of the two sides of the photocell. The error due to

where

V = control voltage

matching can be eliminated by trimming R .

e_out

------- = ---------- = Gain

e_inV_C

V_REF

Figure 10. Electrically Programmable Gain

Application Notes—Analog Optical Isolators

APPLICATION NOTE #2

Handling and Soldering AOIs

All opto components must be handled and soldered with care,

especially those that use a cast or molded plastic and lead frame

construction like the LEDs used in AOIs.

In LED lead frame construction, the emitter chip is mounted directly to

one lead and a wire bond is made from the chip to the other lead. The

encapsulating plastic is the only support for the lead frame. Care must

be taken when forming the leads of plastic opto packages. Excessive

mechanical force can cause the leads to move inside the plastic

package and damage the wire bonds. Weakened bonds can then

“open up” under further mechanical or thermal stressing, producing

open circuits.

When hand soldering, it is important to limit the maximum temperature

of the iron by controlling the power. It is best if a 15W or 25W iron is

used. The maximum recommended lead soldering temperature (1/16"

from the case for 5 seconds) is 260°C. An RMA rosin core solder is

recommended.

In order to form leads safely, it is necessary to firmly lamp the leads

near the base of the package in order not to transfer any force

(particularly tension forces) to the plastic body. This can be

accomplished either through use of properly designed tooling or by

firmly gripping the leads below the base of the package with a pair of

needle nose pliers while the leads are being bent.

Sn60 (60% tin / 40% lead) solder is recommended for wave soldering

opto components into printed circuit boards. Other alternatives are

Sn62 and Sn63. The maximum recommended soldering temperature

is 260°C with a maximum duration of 5 seconds.

The amount of tarnish on the leads determines the type of flux to use

when soldering devices with silver plated leads.

Condition of Leads

Recommended Flux

Clear Bright Finish

(Tarnish Free)

RMA - Mildly Activated

Dull Finish

(Minimal Tarnish)

RMA - Mildly Activated

RA - Activated

Examples of Tooling Fixtures Used to Form Leads

Light Yellow Tint

(Mild Tarnish)

For highest reliability, avoid flush mounting the AOI body on the printed

circuit board. This minimizes mechanical stress set up between the

circuit board and the LED and photocell packages. It also reduces

solder head damage to the packages.

Light Yellow / Tan Color

(Moderate Tarnish)

AC - Water Soluble,

Organic Acid Flux

Dark Tan / Black Color

(Heavy Tarnish)

Leads Need to be Cleaned

Prior to Soldering

Cleaners designed for the removal of tarnish from the leads of

electronic components are acidic and it is best to keep the immersion

time as short as possible (less than 2 seconds) and to immediately

wash all devices thoroughly in ten rinses of deionized water.

Good printed circuit board layout avoids putting any spreading (plastic

under tension) force on the leads of the LED and photocell.

Application Notes—Analog Optical Isolators

The best policy is one which prevents tarnish from forming. Tarnish,

2. The exact requirement of the cleaning process will vary from

which is a compound formed when silver reacts with sulfur (Ag S), can

customer to customer and application to application.

be prevented by keeping the components away from sulfur or sulfur

compounds. Since two major sources of sulfur are room air and paper

products, it is best to store the devices in protective packaging such as

a “silver saver” paper or tightly sealed polyethylene bags.

3. Additives and concentrations will vary from supplier to supplier.

Because of these uncertainties, our recommendation is that all

customers carefully evaluate their own cleaning process and draw their

own conclusions about the effectiveness and reliability of the process.

PerkinElmer cannot assume any responsibility for damage caused by

the use of any of the solvents above or any other solvents used in a

cleaning process.

After soldering, it is necessary to clean the components to remove any

rosin and ionic residues. For a listing of recommended cleaning agents

please refer to Application Notes #3.

APPLICATION NOTE #3

Recommended Cleaning Agents

The construction of an AOI consists of a cast epoxy LED, ceramic

photocell, a molded case and epoxy as the end fill. This construction

allows a wide variety of cleaning agents to be sued after soldering.

In many cases the devices will be exposed to a post solder cleaning

operation which uses one or more solvents to remove the residual

solder flux and ionic contaminants. Only certain cleaning solvents are

compatible with the plastics used in the AOI packages.

Recommended

Not Recommended

Arklone A

Arklone K

Arklone F

Acetone

Carbon Tetrachloride

Methyl Ethyl Ketone

Methylene Chloride

Trichloroethylene (TCE)

Xylene

Blaco-Tron DE-15

Blaco-Tron DI-15

Freon TE

Freon TES

Trichloroethane FC-111

Trichloroethane FC-112

Freon TF

Freon TE-35

Freon TP

Freon TF-35

Genesolv D

Genesolv DE-15

Genesolv DI-15

Isopropyl Alcohol

Water

Freon TA

Freon TMC

Freon TMS

Genesolv DA

Genesolv DM

Genesolv DMS

This listing of recommended/not recommended solvents represents

only a very small percentage of available chemical cleaning agents.

Even with this list of recommended solvents it is important to be aware

that:

1. Solvent exposure times should be as short as possible.

PerkinElmer Optoelectronics

Warranty Statement

PerkinElmer Optoelectronics warrants that all items sold will be free from defects in materials and

workmanship under normal use and service for a period of one year from the date of shipment. If

PerkinElmer Optoelectronics receives notice of such defects during the warranty period, PerkinElmer

Optoelectronics shall, at its option, repair or replace any defective components or credit the purchaser's

account with the purchase price paid. This warranty shall not apply to items that have been (a) subject

to misuse, neglect, accident, damage in transit, abuse or unusual hazard; (b) altered, modified or

repaired by anyone other than PerkinElmer Optoelectronics; or (c) used in violation of instructions

furnished by PerkinElmer Optoelectronics. The Buyer should contact PerkinElmer Optoelectronics for a

return authorization number prior to shipping returned parts.

The specific PerkinElmer Optoelectronics' products shown in this catalog are not authorized or

recommended for use as critical components in life support systems or in surgical implant devices

wherein a failure or malfunction of the PerkinElmer Optoelectronics product may directly threaten life or

cause personal injury. The Buyer agrees to notify PerkinElmer Optoelectronics of any such intended

application and to proceed only after receiving the expressed written approval of an officer of

PerkinElmer Optoelectronics. Additionally, the user of PerkinElmer Optoelectronics components in life

support or implant applications assumes all risks of such use and indemnifies PerkinElmer

Optoelectronics against all damages.

In order to provide the best possible products, PerkinElmer Optoelectronics reserves the right to change

specifications without prior notice. Information supplied in PerkinElmer Optoelectronics' catalogs, data

sheets, and other literature, and information supplied by PerkinElmer Optoelectronics' technical support

personnel is believed to be reliable, however, PerkinElmer Optoelectronics cannot assume responsibility

for omissions, errors, or misapplication of this information.

It is the responsibility of the Buyer to determine the suitability of PerkinElmer Optoelectronics/ products

and recommendations in his own specific application, particularly when the products are operated at or

near their maximum rating specifications. No license is granted by implication or otherwise of any

patent, copyright, or trademark right of PerkinElmer Optoelectronics or others.

PerkinElmer Optoelectronics' warranty, as stated above, shall not be affected or changed by, and no

obligation or liability shall grow out of, PerkinElmer Optoelectronics' providing technical advice or service

to the Buyer.

PERKINELMER OPTOELECTRONICS MAKES NO OTHER WARRANTIES, EXPRESSED OR

IMPLIED, AND EXPRESSLY EXCLUDES AND DISCLAIMS ANY WARRANTIES OF

MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. THE REMEDIES PROVIDED

HEREIN ARE THE BUYER'S SOLE EXCLUSIVE REMEDIES. PERKINELMER OPTOELECTRONICS

SHALL NOT BE LIABLE FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL

DAMAGES, WHETHER BASED ON CONTRACT, TORT, OR ANY LEGAL THEORY. PERKINELMER

OPTOELECTRONICS' LIABILITY ON ANY CLAIM SHALL IN NO CASE EXCEED THE PRICE

ALLOCABLE TO THE ITEM WHICH GIVES RISE TO THE CLAIM.

Quality Statement

PerkinElmer Optoelectronics’ business is the design, development, and production of optoelectronic components

and assemblies. Our development and manufacturing activities focus on achieving and maintaining consistent

product quality and high levels of reliability. PerkinElmer produces devices and assemblies for the commercial,

industrial, automotive, and medical markets.

PerkinElmer’s commitment to quality emphasizes designed-in quality, problem prevention, and closed loop cor-

rective action. This concept of quality is implemented through the use of fully documented procedures, in-

process monitoring and process control (including SPC), and 100% production testing of devices using state-of-

the-art automated test equipment. As a world class manufacturer, PerkinElmer’s concept of product quality

includes Total Quality Management (TQM) and Just In Time (JIT) delivery.

Quality is a measure of how well a device conforms to its specifications. Reliability is a measure of how well a

device performs over time. PerkinElmer insures the reliability of its products by careful design and by the period-

ic testing of random samples taken from the manufacturing lines. Reliability tests include temperature cycles,

thermal shock, room ambient life tests, elevated temperature life tests, high and low temperature storage, tem-

perature/humidity tests, and water immersion.

PerkinElmer also performs special tests covering a wide range of environmental and life stress conditions to

support non-standard, custom applications. The information generated not only assures the customer that the

device will work well in a particular application, but also contributes to our data base for continual product

improvement.

Driven by our goal of continuous improvement and the needs of customers, PerkinElmer runs an active product

improvement program. PerkinElmer continuously evaluates new materials, manufacturing processes, and pack-

aging systems in order to provide our customers with the best possible product.

PerkinElmer’s quality works: we are an ISO 9000 and QS 9000 certified supplier (ship to stock - no inspection

required) to a number of major customers.

Additional Sensor Products Catalogs

USA:

Europe:

Asia:

PerkinElmer Optoelectronics

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St. Louis, MO 63132

Phone: (314) 423-4900

Fax: (314) 423-3956

PerkinElmer Optoelectronics

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D-65199 Wiesbaden

Germany

Phone: +49 611 492 0

Fax: +49 611 492 170

PerkinElmer Optoelectronics

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Phone: 852 2590 0238

Fax: 852 2590 0513

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