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AS3642

Datasheet - A p p l i c a t i o n I n f o r m a t i o n

1. Write 0x20 into register 0x03 (Control register) [Enable assist light with default 72mA].

2. Read back

3. Write 0x00 into register 0x03 [Power off]

4. Read register 0x04 (Fault register) - must return 0x00, otherwise the LED is open or shorted

See Table 14 to identify the different possible soldering errors:

A typical use case for the AS3642 is to generate a 480ms, 500mA flash pulse. The programming example is shown in

Table 15:

7. Alternative testing method: Instead of reading the internal registers, the current into the AS3642 can be

measured. During assist light mode, the supply current must increase by at least 60mA. If an error is

detected, the current source and the DCDC is automatically switched off - see Protection and Fault Detec-

tion Functions on page 11

Table 14. How-to identify errors

Error

Identified by

SCL or SDA broken

writing 0x20 to 0x03 and read back of register 0x03 does not return 0x20

writing 0x20 to 0x03 and read back of register 0x03 does not return 0x20 - see DCDC

Broken Coil Detection on page 11

Flash LED shorted

register fault_led_short (see page 19) is set

Flash LED open

register fault_ovp (see page 19) is set

Table 15. I

Sequence

C-Syntax

Purpose/Action

write 0xA1 to register 0x80h

AMSWriteByte(0x80,0xA1);

Use password to unlock next I

write 0xFF to register 0x02h

AMSWriteByte(0x02,0xFF);

Set 500mA mode

(current_mode (page 16)=11b)

and current (page 17) to 500mA

write 0x3F to register 0x03h

AMSWriteByte(0x03,0x3F);

Set flash_timer (page 18) to 480ms and

mode (page 18) to flash

(which automatically fires the flash and stops

it after flash_timer expired)

- no further action required -

the AS3642 automatically returns to

shutdown mode