SIP12401 データシートの表示（PDF） - Vishay Semiconductors

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SIP12401

Boost Controller For Double AA Cell or Li-Ion Battery For White LED Application

Vishay Semiconductors 

SiP12401

Vishay Siliconix

FUNCTIONAL BLOCK DIAGRAM

FB

XSHD

Compensation

-

E/A

+

Reference and Soft-Start

Oscillator

+

PWM

-

VIN

Driver

AGND

EXT

PGND

DETAILED OPERATION

SiP12401 is a 600 kHz boost controller IC, packaged in 6-pin

MLP33, for white LED applications. It features fixed

frequency voltage mode PWM control with internal frequency

compensation. With the low rDS(on) external power MOSFET,

this device maintains high efficiency over a wide range of

load current.

Soft-Start

During soft-start, the loop compensation guarantees the slow

increase of the output voltage and inrush current, so that no

large voltage overshoot and inrush current occur when the

soft-start is ended.

PWM operation

After soft-start, the device is working in PWM operation with

a fixed frequency of 600 kHz.

APPLICATION INFORMATION

White LED Brightness Control

The current of white LED can be adjusted by PWM signal on

the XSHD pin or by a variable dc voltage to control its

brightness, (see Figure 1.) As control voltage VCTRL

increases, the voltage drop on R2 increases and the voltage

drop on R1 decreases. Thus, the LED current decreases.

The selection of R2 and R3 will make the current from VCTRL

much smaller than LED current and much larger than the FB

pin bias current.

VIN

10 µF

XSHD

I LED

0.3 V

15 Ω

0.3 - VCTRL R2

15 Ω

R3

22 µH

2

VIN

1

XSHD

4

AGND

SiP12401

3

FB

6

EXT

PGND

5

www.vishay.com

4

MBR0520

4.7 µF

Si2302ADS

R2

1 kΩ

R3

3.9 kΩ

VCTRL

15 Ω

Document Number: 73193

S-71822-Rev. C, 03-Sep-07

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