SY88982LMG [MICREL]

3.3V, 2.7Gbps High Current, Low Power Laser Driver for FP/DFB Lasers; 3.3V ， 2.7Gbps的高电流，低功率激光驱动器的FP / DFB激光器


型号：	SY88982LMG
厂家：	MICREL SEMICONDUCTOR
描述：	3.3V, 2.7Gbps High Current, Low Power Laser Driver for FP/DFB Lasers 3.3V ， 2.7Gbps的高电流，低功率激光驱动器的FP / DFB激光器驱动器电信集成电路异步传输模式 ATM
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中文：	中文翻译
下载：	下载PDF数据表文档文件

SY88982L

3.3V, 2.7Gbps High Current, Low Power

Laser Driver for FP/DFB Lasers

General Description

Features

The SY88982L is a single 3.3V supply, low power

consumption, small form factor driver for

telecom/datacom applications using FP/DFB lasers

at data rates up to 2.7Gbps. The driver can deliver

modulation current up to 90mA, and the high

compliance voltage it offers, makes the part suitable

for high-current operation (with the laser AC- or DC-

coupled to it). This device is intended to be used

with Micrel’s MIC3000/1 Optical Transceiver

Management IC, which allows for both modulation

and bias current control and monitoring, automatic

power control, and temperature compensation.

• 2.4V minimum laser compliance voltage for high-

current DC-coupled applications

• 48mA power supply current typical

• Operation up to 2.7Gbps

• Modulation current up to 90mA

• Designed for use with the MIC3000/1

• Small form factor 16-Pin (3mm x 3mm) MLF™

package

• Laser may be DC- or AC-coupled

Applications

All support documentation can be found on Micrel’s

web site at: www.micrel.com.

• Multi-rate LAN, MAN applications up to 2.7Gbps:

FC, GbE, SONET OC3/12/24/48 and SDH

STM1/4/8/16

• SFF, SFP modules

Markets

• Telecom, Datacom

________________________________________________________________

Typical Application

Laser AC-Coupled to the Driver

Laser DC-Coupled to the Driver

MLF and MicroLeadFrame are trademarks of Amkor Technology, Inc.

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April 2005

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SY88982L

Functional Block Diagram

Ordering Information⁽¹⁾

Part Number

Package

Type

Operating

Range

Package Marking

Lead Finish

SY88982LMG

SY88982LMGTR⁽²⁾

Notes:

MLF-16

Industrial

982L with Pb-Free bar-line indicator

NiPdAu Pb-Free

1. Contact factory for die availability. Dice are guaranteed at T_A= +25°C, DC Electricals only.

2. Tape and Reel.

Pin Configuration

16-Pin MLF^TM(MLF-16)

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SY88982L

Pin Description

Pin Name

Pin Number

Pin Function

1, 4, 7, 8, 13

GND

Ground. Ground and exposed pad must be connected to the plane of the most

negative potential.

DIN+

DIN–

VCC

Non-inverting data input. Internally terminated with 50ꢀ to a reference voltage.

Inverting data input. Internally terminated with 50ꢀ to a reference voltage.

5, 6

Supply Voltage. Bypass with a 0.1ꢀF//0.01ꢀF low ESR capacitor as close to VCC

pin as possible.

9, 10

MOD–

MOD+

Inverted modulation current output. Outputs modulation current when input data is

negative.

11, 12

Non-inverted modulation current output. Outputs modulation current when input

data is positive.

VREF

Reference Voltage. Install a 0.1ꢀF capacitor between VREF and VCC.

IM_SET

Modulation current setting and control. The voltage applied to this pin will set the

modulation current. To be connected to the MIC3000/1 pin 24 (VMOD+). Input

impedance 25Kꢀ.

/EN

A low level signal on this pin will enable the output stage of the driver. Internally

pulled down with 75Kꢀ.

Truth Table

DIN+

DIN-

/EN

MOD+⁽¹⁾

MOD-

Laser Output⁽²⁾

Notes:

I_MOD= 0 when MOD+ = H.

2. Assuming that the laser is tied to MOD+.

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April 2005

Micrel, Inc.

SY88982L

Absolute Maximum Ratings⁽¹⁾

Operating Ratings⁽²⁾

Supply Voltage (V_IN) .............................–0.5V to +4.0V

CML Input Voltage (V_IN)............V_CC–1.2V to V_CC+0.5V

TTL Control Input Voltage (V_IN).....................0V to V_CC

Lead Temperature (soldering, 20sec.)............. +260°C

Storage Temperature (T_s) .................–65°C to +150°C

Supply Voltage (V_CC)............................ +3.0V to +3.6V

Ambient Temperature (T_A)..................–40°C to +85°C

Package Thermal Resistance⁽³⁾

MLF™

(ꢀ_JA) Still-air................................................ 60°C/W

(ꢁ_JB)............................................................ 33°C/W

DC Electrical Characteristics

T_A= –40°C to +85°C and V_CC= +3.0V to +3.6V, unless otherwise noted. Typical values are V_CC= +3.3V, T_A= 25°C, I_MOD

= 60mA.

Symbol

I_CC

Parameter

Condition

Min

Typ

Max

65⁽⁴⁾

Units

Power Supply Current

Modulation currents excluded

V_{MOD_MIN}

Minimum Voltage Required at

the Driver Output (headroom) for

Proper Operation

0.6

R_IN(DATA)

V_ID

Input Resistance (DIN+, DIN-)

Differential Input Voltage Swing

2400

0.8

ꢀ

mV_pp

200

/EN Low

/EN High

R_{IN (IMOD_SET)}

V_{IM_SET}

I_{M_SET}Input Resistance

kꢀ

Voltage Range on I_{M_SET}Pin

I_MODrange 10mA to 90mA

1.2

AC Electrical Characteristics

T_A= –40°C to +85°C and V_CC= +3.0V to +3.6V, unless otherwise noted. Typical values are V_CC= +3.3V, T_A= 25°C, I_MOD

= 60mA.

Symbol

Parameter

Condition

NRZ

Min

0.155

Typ

Max

2.7

Units

Gbps

Data Rate

Modulation Current⁽⁵⁾

I_MOD

AC-coupled

DC-coupled

70⁽⁶⁾

Current at MOD+ when the device is

disabled

I_{MOD_OFF}

Modulation OFF Current

750

ꢁA

t_r

t_f

Output Current Rise Time

Output Current Fall Time

Total Jitter

20% to 80%, I_MOD= 60mA, 15ꢂ load

@2.5Gbps data rate

ps_PP

Pulse-Width Distortion

Notes:

1. Permanent device damage may occur if absolute maximum ratings are exceeded. This is a stress rating only and functional operation is

not implied at conditions other than those detailed in the operational sections of this data sheet. Exposure to absolute maximum ratings

conditions for extended periods may affect device reliability.

2. The data sheet limits are not guaranteed if the device is operated beyond the operating ratings.

3. Package Thermal Resistance assumes exposed pad is soldered (or equivalent) to the devices most negative potential on the PCB. y_JB

uses a 4-layer and q_JAin still air unless otherwise stated.

4. I_CC= 65mA for worst-case conditions with I_MOD= 90mA, T_A= +85°C, V_CC= 3.6V.

5. Load = 15ꢀ.

6. Assuming V_CC= 3.0V, Laser bandgap voltage = 1V, laser package inductance = 1nH, laser equivalent series resistor = 5ꢀ, and damping

resistor = 10ꢀ.

M9999-0414505

hbwhelp@micrel.com or (408) 955-1690

April 2005

Micrel, Inc.

SY88982L

Typical Operating Characteristics

Test Circuit

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April 2005

Micrel, Inc.

SY88982L

Functional Characteristics

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SY88982L

Input and Output Stages

Figure 1b. Simplified Output Stage

Figure 1a. Simplified Input Stage

Interfacing the Input to Different Logic Drivers

Figure 2b. AC-Coupling to LVPECL Driver

Figure 2a. DC-Coupling to LVPECL Driver

Figure 2c. AC-Coupling to CML Driver

Figure 2d. AC-Coupling to LVDS Driver

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SY88982L

parasitic inductance of the laser is neglected

(compensated for) and the maximum drop across

the laser (1.6V) considered while keeping a

minimum of 600mV headroom for the driver, then

the maximum damping resistor that allows a 70mA

modulation current into the laser is:

Application Information

The typical applications diagram on the first page

shows how to connect the driver to the laser, single

ended. To improve transition time and laser

response, the laser can be driven differentially as

shown in Figures 3 and 4. Driving the laser

differentially will also minimize the cross talk with the

rest of the circuitry on the board, especially the

receiver.

_dmax= (VCC – 0.6V – 1.6V)/0.07A.

The worst case will be with V_CC= 3.0V, leading to

_dmax= 11.4ꢀ.

On the other hand, the small is the value of R_d, the

higher is the overshoot/undershoot on the optical

signal from the laser. In the circuit shown in Figure

3, the RC compensation network across the driver

DC-Coupling

In addition to the low power consumption and high

modulation current, the SY88982L offers a high

compliance voltage. As can be seen in the “Typical

Operating Characteristics” section (I_modvs. V_MOD

curves), the minimum voltage needed at the output

of the driver for proper operation is less than 600mV,

leaving a large headroom, V_CC–600mV, to the laser

with the damping resistor. To show the importance

of this high compliance voltage, consider the voltage

drops along the path from VCC to ground through

the laser, damping resistor, and driver:

outputs (MOD+ and MOD-) allows the user R_d

10ꢀ. The optical eye diagrams at data rates of

155Mbps/622Mbps/1.25Gbps/2.5Gbps, shown in

“Functional Characteristics” section, are all obtained

with the same circuit using R_d= 10ꢀ, R_Comp= 100ꢀ,

and C_Comp= 3pF. The compensation network may

change from one board to another and from one

type of laser to another. An additional compensation

network (RC) can be added at the laser cathode for

further compensation and eye smoothing.

VCC = Driver Headroom + V_Rd+V_laser

V_Rd= Rd * I_mod

V_laser= V_band-gap+ R_laser* I_mod+ Ldi/dt

V_band-gap+ R_laser* I_mod= 1.6V at maximum for a

Fabry Perrot or a DFB laser.

Ldi/dt is the voltage drop due to the laser parasitic

inductance during I_modtransitions. Assuming L =

1nH, t_r= t_f= 80ps (measured between 20% and 80%

of I_mod), and I_mod= 70mA (42mA from 20% to 80%),

then Ldi/dt will be equal to 525mV. This number can

be minimized by making the laser leads as short as

possible and using an RC compensation network

between the cathode of the laser and ground or

across the laser driver outputs as shown in Figure 3.

Figure 3. Laser DC-Coupled

To be able to drive the laser DC-coupled with a high

current, it is necessary to keep the damping resistor

as small as possible. For example, if the drop due to

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April 2005

Micrel, Inc.

SY88982L

AC-Coupling

of identical bits in a low data rate application. This

leads to higher pattern-dependant jitter in the

transmitter signal. 0.1µF is found to be good for all

applications from 155Mbps to 2.7Gbps.

When trying to AC couple the laser to the driver, the

headroom of the driver is no longer a problem since

it is DC isolated from the laser with the coupling

capacitor. The headroom of the driver is determined

by the pull-up network at the output. In Figure 4, the

modulation current out of the driver is split between

the pull-up network and the laser. If, for example, the

total pull-up resistor is twice the sum of the damping

resistor and laser equivalent series resistance, only

two thirds (2/3) of the modulation current will be

used by the laser. So, to keep most of the

modulation current going through the laser, the total

pull-up resistors must be kept as high as possible.

One solution consists in using an inductor alone as

pull-up, presenting a high impedance path for the

modulation current and zero ohm (0ꢀ) path for the

DC current offering a headroom of the driver equal

to VCC and almost all the modulation current goes

into the laser. The inductor alone will cause signal

distortion, and, to improve that, a combination of

resistors and inductors can be used (as shown on

Figure 4). In this case, the headroom of the driver is

VCC – R1 x ꢁI_mod, where ꢁI_modis the portion of the

modulation current that goes through the pull-up

network.

AC coupling the laser to the driver brings a solution

to the driver headroom problem at the expense of

extra components, loss of part of the modulation

current wasted in the pull-up network, and additional

power consumption.

When the laser is AC-coupled to the driver, the

coupling capacitor creates a low-frequency cutoff in

the circuit, and its value must be chosen as large as

possible. If the value of the cap is too high, it will

slow down the fast signals edges, and, if its value is

too small, it won’t be able to hold a constant charge

between the first bit and the last bit of a long string

Figure 4. Laser AC-Coupled

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April 2005

Micrel, Inc.

SY88982L

Package Information

16-Pin (3mm x 3mm) MLF™ (MLF-16)

MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA

TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http:/www.micrel.com

The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel

for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.

Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a

product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended

for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant

injury to the user. A Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk

and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale.

M9999-0414505

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April 2005

SY88982LMG [MICREL]

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