www.austriamicrosystems.com/AS3644

1.2.2

20 - 23

AS3644

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

Application Self Testing Guideline

Using the in-build self testing features of the AS3644, the errors as shown in Figure 24 during the assembling and sol-

dering of the AS3644, can be detected - this simplifies and can reduce cost during manufacturing:

Figure 24. Self Testing - Detecting Assembling and Soldering Errors

The self testing procedure is simple:

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 14to identify the different possible soldering errors:

4. Alternative testing method: Instead of reading the internal registers, the current into the AS3644 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 10

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 17) is set

Flash LED open

register fault_ovp (see page 17) is set

 







 















!



AS3644