AS3630 datasheet(21/72 Pages) AMSCO

21 / 72 page

8A Supercap Flash Driver

AS3630 – 21

The AS3630 is a highly efficient dual DCDC Supercap charger

charging and balancing the Supercap and operating a LED flash

at up to 8A current.

The principle of operation of a AS3630 is as follows:

Charge the Supercap on VSUPERCAP to e.g. 5.5V - see

Supercap Charging/Discharge/Pre-charge to VIN

Torch (or PWM) operation of the LED does not depend

on a charge Supercap - see “Torch/PWM Operation” on

page 25.

Use DCDC1 to step up from VIN to VDCDC to source one

part of the LED_OUT current; in parallel use DCDC2 to

step up from -VSUPERCAP to VDCDC to source the

remaining part of the flash current - see Flash Operation.

Using this approach a very high current flash operation can be

performed using considerable low current from the battery

(usually batteries have a defined strict current limit, so the full

flash current cannot be supplied directly from the battery only).

Supercap Charging/Discharge/Pre-charge to VIN

The charging of the Supercap is performed in following steps:

• Pre-Charge - (see Figure below): Charge the Supercap

close to VIN - initiated by setting mode_setting = Supercap

pre-charge1, 2:

The switch between SW1 and VDCDC is closed and ICHARGE

(set by charge_current) is used to control the charging

current. Use charge_current=00b for a special low power

mode only consuming IPRE_CHARGE_LOW_POWER.

1. This mode is usually used during standby of the system - the Supercap is kept at VIN; this will reduce the charging time, when the

camera is operated and the Supercap has to be charged to its final end of charge voltage (e.g. 5.5V)

2. In pre-charge the Supercap is always charged close to VVIN; therefore VSUPERCAP_EOC ≥ VVIN

Detailed Descriptions

AS3630 Datasheet(PDF) 21 Page - ams AG