PC112 [SITI]

Step Up Converter for White LED Driver; 升压转换器，用于白光LED驱动器


型号：	PC112
厂家：	SILICON TOUCH TECHNOLOGY INC.
描述：	Step Up Converter for White LED Driver 升压转换器，用于白光LED驱动器驱动器转换器升压转换器
文件：	总14页 (文件大小：375K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

PC112/PC113

Version

: A.001

Issue Date : 2004/10/01

File Name : SP-PC112/PC113-A.001.doc

Total Pages: 14

Step Up Converter for White LED Driver

新竹市科學園區展業一路 9 號 7 樓之 1

SILICON TOUCH TECHNOLOGY INC

9-7F-1, Prosperity Road I, Science Based Industrial Park,

Hsin-Chu, Taiwan 300, R.O.C.

Tel：

886-3-5645656

Fax：886-3-5645626

點晶科技股份有限公司

SILICON TOUCH TECHNOLOGY INC.

PC112/PC113

General Description

PC112/PC113 is a compact, high-efficiency step-up DC-DC converter which drives

2-6 series white LEDs with constant current from 3V to 5V. Extremely low shutdown

power supply current ensures the high efficiency of battery system. The PC113 works

at 500KHz, allowing the application of tiny external components. Low feedback voltage

and hence minimal input current from the battery extends battery life.

Built-in N-channel power switches optimize the layout area of PCB. Since

PC112/PC113 drives series LEDs, it regulates the light intensity uniformly. With a single

external resistor or PWM signal, users can easily set the LED current and LED

brightness.

While output loading is open, likes the case of LEDs failure, the duty cycle of the

DC-DC converter will increase rapidly, causing high output voltage to damage the

circuit. To avoid this situation, a Zener diode should be connected to the DC-DC

converter’s output to clamp the output voltage in most applications. However, PC113

has built-in the over-voltage protection circuit to protect the output circuit and thus

eliminates the need of the external Zener diode.

PC112/PC113 is also characterized of the soft-start feature, which limits the inrush

current. It is available in Thin-SOT type package.

Features

1. Typical 85% efficiency

2. No external power switch

3. Low shutdown supply current

4. Low feedback voltage

5. Drives 6 white LEDs 20mA from working voltage 2.0V

±4

% LED output current accuracy

7. Over voltage protection circuit build in(PC113)

8. Soft-start circuit build in

9. Thin 6-pin SOT23-6 package

Application

1. White LED Display Backlighting

2. Cellular Telephones

3. Personal Digital Assistant

4. Digital Cameras

5. Portable Machine

-1-

Version：A.001

點晶科技股份有限公司

SILICON TOUCH TECHNOLOGY INC.

PC112/PC113

Block Diagram

VSS

Soft

Start

Pre-

Driver

Pre

Driver

0.1V

0.5V

OVP

Clock

Genertor

Control

Logic

Soft

Start

Clock

Genertor

Control

Logic

VDD

OVP

VDD

PC113

PC112

Pin Descriptions

Pin No

PIN NAME

Descriptions

PC113 PC112

VSS

Connect inductor to battery

Ground pin

Feedback pin

Enable pin

OVP

VDD

Over voltage protection

Input voltage supply pin

VDD

SiTI

VSS

OVP

PC113

PC112

TopView

-2-

Version：A.001

點晶科技股份有限公司

SILICON TOUCH TECHNOLOGY INC.

PC112/PC113

Absolute Maximum Ratings

Parameter

Symbol

Rating

Unit

Supply Voltage

VDD

5.5

LX Voltage

V_LX

V_EN

P_d

5.5

EN Voltage

Power Dissipation

Storage Temperature

Operating Temperature

Junction Temperature

2.5

^oC

T_stg

T_opr

-65~140

-40~120

160

Electrical characteristics, VDD=3.6V, T_a= 25 ^oC . (unless otherwise specified)

PARAMETER

SYMBOL

CONDITION

MIN

TYP

MAX Unit

Operating Input Voltage

VDD

2.8

3.6

µV/°C

Ω

FB PIN Voltage

V_FB

T_FB

R_SW

T_ON

D_MAX

F_SW

95 105

+92

FB Vol. Temp. Coefficient

Switch-on Resistance

Switch Max On-time

Maximum Duty Cycle

Switching Frequency

Efficiency

I_LED= 20mA

1.5

1.4

1.5 1.6

µS

450 500 550 KHz

µA

I_DD

V_EN=High

V_EN=Low

V_EN=High

V_EN=Low

Supply Current

I_DDQ

0.1

0.2

Shutdown Input Current

*Over voltage protection

I_EN

V_P

*Note1 : Only PC113 build this function

-3-

Version：A.001

點晶科技股份有限公司

SILICON TOUCH TECHNOLOGY INC.

PC112/PC113

Typical application circuit

6.8uH

MBR0520

V_IN

2.8 to 5.0V

I_IN

R₁

4.7uF

22Ω

4.7uF

Zener

VDD

SiTI

1uF

1KΩ

PC112

OFF

5.6Ω

VSS

Fig. 1 Application circuit of PC112

6.8uH

V_IN

2.8 to 5.0V

I_IN

MBR0520

R₁

22Ω

4.7uF

White

LED

x 3

4.7uF

VDD

I_LED

20mA

1uF

SiTI

OVP

PC113

OFF

VSS

R₂

5.6Ω

Fig. 2 Application circuit of PC113

-4-

Version：A.001

點晶科技股份有限公司

SILICON TOUCH TECHNOLOGY INC.

PC112/PC113

Typical performance characteristics

R₁=22Ω, L1=6.8µH, C1=4.7µF, C2=4.7µF, C3=1µF, Schottky diode VF=0.18, T_a= 25 ^oC ,

(unless otherwise specified)

Efficiency vs Load current

0.89

0.88

0.87

0.86

0.85

0.84

0.83

0.82

0.81

0.8

0.88

0.87

0.86

0.85

0.84

0.83

0.82

0.81

0.8

VIN=4.2V

VIN=3.6V

VIN=2.85V

2LEDs

3LEDs

Load current (mA)

Efficiency vs Load current

Feedback voltage vs Load current

0.88

0.87

0.86

0.85

0.84

0.83

0.82

0.81

0.8

0.11

0.108

0.106

0.104

0.102

0.1

4x LEDs

VIN=4.2V

3x LEDs

2x LEDs

VIN=3.6V

0.098

0.096

0.094

0.092

0.09

VIN=2.85V

4LEDs

0.79

0.78

Load current (mA)

Efficiency vs Temperature (High Load)

Efficiency vs Temperature (Light Load)

VIN=2.85V

VIN=4.2V

VIN=3.6V

VIN=4.2V

VIN=2.85V

3 WLEDs, 25mA

3 WLEDs, 5mA

-40

-20

100

120

140

-40

-20

100

120

140

Temperature (degree)

-5-

Version：A.001

點晶科技股份有限公司

SILICON TOUCH TECHNOLOGY INC.

PC112/PC113

Typical performance characteristics (cond.)

Feedback voltage vs Load current

Frequency vs Temperature

0.1

0.098

0.096

0.094

0.092

0.09

560

540

520

500

480

460

440

420

4x LEDs

3x LEDs

2x LEDs

0.088

-20

100

120

Load current (mA)

Temperature (degree)

NOTE1 :The white LED forward voltage is about 3.6V, so PC112/PC113 could drive up to 6

series white LEDs.

NOTE2 : To chose D1(Schottky diode), it must has fast switch characteristics and low

forward voltage. We recommend the MBR0520in this application.

NOTE3 : The ripple of input voltage could be minimized with C1. Thus, a large value of

capacitor C1 is suggested. With the application of a RC-filter (R1 and C2) to VDD

pin, the stability of circuit is enhanced. The ripple of output voltage also could be

improved with C3. In most designs, the low ESR (equivalent series resistance)

capacitors are desirable, like multi-layer capacitor. A 1uF to 2.2uF output

capacitor is sufficient for most applications.

0.095

NOTE4 : I_LED

(A)

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Version：A.001

點晶科技股份有限公司

SILICON TOUCH TECHNOLOGY INC.

PC112/PC113

Application Information

Reference Fig.1 ,condition: Zener=15V, Ta = 25 ^oC , unless otherwise specified

VDD

(AC)

I_IN

V_FB

I_IN

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Version：A.001

點晶科技股份有限公司

SILICON TOUCH TECHNOLOGY INC.

PC112/PC113

General Description

ꢀ

Bias current setting

The PC112/PC113 is a DC/DC converter which provides a regulated current output

from a VDD input of DC 2.8V to 5.0V. Regulating the LED current can be achieved by

setting the resistor of FB pin to ground. So the value of the current setting resistor R2

could be set by:

0.095

R2=

(Ω)

I_LED

ꢀ

Brightness control

The brightness control can be achieved by applying a PWM control signal to EN

pin or by varying the current setting resistor R2, shown as follows.

PC113

PWM

R_A

R_MIN

R_INCR

LEDs

R_B

PWM

R₂

V_ADJ

Fig. 3

Fig. 4

Fig. 5

We could apply a digital PWM signal (100Hz~3KHz) to EN pin (Fig. 3) to generate

a LED current waveform identical to that of the PWM signal waveform. The average

output LED current is calculated:

0.095

I_LED

x Duty of PWM

(A)

Another control method is to vary the value of the current setting resistor (Fig. 4).

R_MIN× R_INCR

R_MIN+ R_INCR

0.095

I_LED

which R2 =

, PWM is High

(A)

A DAC can also be applied for brightness control, which is shown in Fig. 5. If V_ADJ

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Version：A.001

點晶科技股份有限公司

SILICON TOUCH TECHNOLOGY INC.

PC112/PC113

(output of a DAC or Ambient Light Sensor) increases, the output voltage will decrease.

For example, R_A=6.2KΩ, R_B=82KΩ, V_ADJ= 4V, V_FB1will set to 0.05V, so the LED’s

current will be half .

ꢀ

Open circuit protection (PC113 only)

When the LEDs are disconnected from the circuit or the LEDs fail, PC113 will

switch to maximum duty cycle. This situation results in a high output voltage and may

cause the LX pin voltage to exceed its maximum rating of 24V and thus damages

output circuit. Normally, a Zener diode is applied to clamp the high voltage; however,

PC113 has built-in the over-voltage protection circuit, and thus no external component

is required.

ꢀ

Recommended PCB layout

1. C2 is placed as close to PC112/113 as possible.

2. Minimize the length and area of all traces connecting to LX pin.

3. The power path : VDD ꢁL1 ꢁLX ꢁD1 ꢁC3 should be kept as short as

possible to avoid EMI.

4. Fig. 6 shows the exemplary test board layout. (Reference page4. typical

application circuit )

Fig. 6

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Version：A.001

點晶科技股份有限公司

SILICON TOUCH TECHNOLOGY INC.

PC112/PC113

ꢀ Recommended solder pad

1.6mm

3.1 mm

Fig. 7

-10-

Version：A.001

點晶科技股份有限公司

SILICON TOUCH TECHNOLOGY INC.

PC112/PC113

Package Specification (SOT23-6)

θ1

A₂

A₁

Dimensions in Millimeters

SYMBOL

MIN

NOM

MAX

A₁

A₂

1.00

0.00

0.70

0.35

0.10

2.70

1.40

－

1.10

－

1.30

0.10

0.90

0.50

0.25

3.10

1.80

－

0.80

0.40

0.15

2.90

1.60

1.90(TYP)

2.80

2.60

0.37

3.00

－

θ1

1°

5°

9°

-11-

Version：A.001

點晶科技股份有限公司

SILICON TOUCH TECHNOLOGY INC.

PC112/PC113

Package Specification (SOT23-5)

θ1

A₂

A₁

DIMENSIONS IN MILLIMETERS

SYMBOL

MIN

NOM

MAX

A₁

A₂

1.00

0.00

0.70

0.35

0.10

2.70

1.40

－

1.10

－

1.30

0.10

0.90

0.50

0.25

3.10

1.80

－

0.80

0.40

0.15

2.90

1.60

1.90(TYP)

2.80

2.60

0.37

3.00

－

θ1

1°

5°

9°

-12-

Version：A.001

點晶科技股份有限公司

SILICON TOUCH TECHNOLOGY INC.

PC112/PC113

The products listed herein are designed for ordinary electronic applications, such as electrical

appliances, audio-visual equipment, communications devices and so on. Hence, it is advisable

that the devices should not be used in medical instruments, surgical implants, aerospace

machinery, nuclear power control systems, disaster/crime-prevention equipment and the like.

Misusing those products may directly or indirectly endanger human life, or cause injury and

property loss.

Silicon Touch Technology, Inc. will not take any responsibilities regarding the misusage of

the products mentioned above. Anyone who purchases any products described herein with the

above-mentioned intention or with such misused applications should accept full responsibility

and indemnify. Silicon Touch Technology, Inc. and its distributors and all their officers and

employees shall defend jointly and severally against any and all claims and litigation and all

damages, cost and expenses associated with such intention and manipulation.

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Version：A.001

PC112 [SITI]

相关型号：

PC112-H25D-C0

PC112A

PC112B

PC112C

PC112L

PC112L1

PC112L1I

PC112L1P0

PC112L2

PC112L2P0

PC112L5

PC112L5I