AS3630 datasheet(23/72 Pages) AMSCO

23 / 72 page

8A Supercap Flash Driver

AS3630 – 23

Figure AS3630 – 20:

Supercap Charging

• Charging - (see Figure above): Once the voltage on

VSUPERCAP

≥ VIN and mode_setting = “Supercap charge”,

the main charging can start: The DCCD1 converter is

operated and the switch between VDCDC and SW2 is closed.

The charging current in this phase is defined by the LDCDC1

peak current limit (programmed by coil1_peak).

Once the voltage on VSUPERCAP reaches

end_of_charge_voltage4, the peak current through LDCDC1

is reduced to 500mA. Charging is finished when the

voltage on VSUPERCAP again reaches

end_of_charge_voltage. Then the flash status_eoc is set and

if enabled by status_eoc_mask, INT is pulled low.

If keep_sc_charged=1, AS3630 will continuously check the

voltage on VSUPERCAP if it drops below

end_of_charge_voltage and automatically recharge the

Supercap with 5mA.

• Keep charge: Even in torch or PWM operation5 of the LED

connected to LED_OUT the charge on VSUPERCAP can be

maintained by setting keep_sc_charged=1. Then the

current source IKEEP_CHARGE will be used to charger

VSUPERCAP from VDCDC (without exceeding

end_of_charge_voltage).

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

≥ VVIN

5. In these modes DCDC2 is not used as LED_OUT can be driven directly with DCDC1 from VIN.

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AS3630 Datasheet(PDF) 23 Page - ams AG