A8425 データシートの表示（PDF） - Allegro MicroSystems

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A8425

High Current Photoflash Capacitor Charger with IGBT Driver for Two Li+ Batteries

Allegro MicroSystems 

A8425

High Current Photoflash Capacitor Charger

with IGBT Driver for Two Li+ Batteries

Features and Benefits

▪ Wide battery voltage range: 1.5 to 11 V

▪ Integrated 55 V DMOS switch in very thin profile

3 mm × 3 mm, 0.75 mm nominal height package

▪ Peak current limit continuously adjustable from 1.0 to 3.2 A

▪ Output voltage sensing on primary side: no resistor divider

required

▪ >75% efficiency

▪ Fast charge time

▪ Charge Complete indication

▪ Flexible, high current IGBT drive

▪ Independent IGBT driver supply

▪ Separate sink and source pins with 6 Ω pull-up and

20 Ω pull-down

▪ Interlocked trigger pin improves noise immunity

▪ No primary-side Schottky diode needed

Package: 16-contact TQFN (suffix ES)

Description

The A8425 charges photoflash capacitors for digital cameras,

camcorders, and DSC combos. An integrated 55 V DMOS

switch drives the transformer in a flyback topology optimized

for 2-cell Li+ battery input. An integrated IGBT driver with

separate source and sink pins allows high performance red-eye

reduction implementation.

TheA8425 offers programmable peak switch current limit from

1.0 to 3.2 A, continuously adjustable using a resistor to ground.

A proprietary control scheme optimizes the capacitor charging

time. Low quiescent current and low shutdown current further

improve system efficiency and extend battery life.

The A8425 is available in 16-contact 3 mm × 3 mm TQFN

packages. This small, very thin profile (0.75 mm nominal overall

height) package is ideal for space-constrained applications. It

is lead (Pb) free, with 100% matte-tin leadframe plating.

Applications include:

▪ SLR camera flash

▪ Digital camcorder/DSC combo flash

▪ 2 Li+ input strobe

Approximate Scale 1:1

A8425-DS, Rev. 1

Typical Application

Bias Input

3.0 to 5.5V

Battery Input

1.5 to 11 V

C2

TLIM

+

VIN VBAT

VOUT Detect

C1

SW

ISET

RSET

Control

Block

ISW sense

1 : 10

COUT

100 μF

315 V

CHARGE

TRIGGER1

TRIGGER2

DONE

VDRV

IGBT Driver

GND

VPULLUP

100 kΩ

DONE

GSRC

GSNK

IGBT Gate

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