A8438(2005) Ver la hoja de datos (PDF) - Allegro MicroSystems

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Fabricante

A8438
(Rev.:2005)

Photoflash Capacitor Charger with IGBT Driver

Allegro MicroSystems 

A8438 Photoflash Capacitor Charger with IGBT Driver

When the A8438 charges a fully-discharged photoflash capacitor,

ISecondary decreases very slowly due to the low initial VOUT. The

A8438 internal timer (Timer mode) sets a maximum timeframe of

18 μs for the off-time as long as the SW node voltage is greater

than 1.2 V. When the off-time passes 18 μs, the internal MOSFET

switch is turned on, initiating the next charging cycle .

Input Current Limiting

The peak input current, ISWLIM , can be set to three levels by

configuring the ILIM pin:

ISWLIM Setting

(A)

1.6

1.8

2.0

ILIM Pin

Connection

External ground

Float

Pull up to IC supply voltage

with a 1 to 10 kΩ resistor

Lower input current offers the advantage of a longer battery

lifetime. For faster charging time, however, use the highest

current limit. ISWLIM may be adjusted during charging.

A8438-DS, Rev. 1

Allegro MicroSystems, Inc.

10

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

www.allegromicro.com

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