Other Parts Discussed in Thread: AM3352
Hi,
I received the question from the customer.
We are testing one of our products and we are getting an incorrect power-down sequence.
The PMIC does not have a battery connected. PMIC register settings are default, and shutdown procedure is initiated by Linux shutdown -h now command. Hardware implementation is similar to beaglebone black schematics, but with FB_WLED LCD backlight implementation. Our power-on sequence is correct:
[SYS_5V] -> [VDDS_RTC (LDO1)] -> [LDO2 (3.3V),LDO3 (1.8V), LDO4 (3.3V)] -> [ VDDS_DDR (DCDC1)] -> [VDD_MPU (DCDC2), VDD_CORE (DCDC3)].
But our power-down sequence is not:
[SYS_5V] -> [LDO2 (3.3V), LDO4 (3.3V)] -> [VDD_MPU (DCDC2), VDD_CORE (DCDC3)] -> [LDO3 (1.8V)] -> [VDDS_DDR (DCDC1)] -> [VDDS_RTC (LDO1)].
What is this cause?
Is this why V_SYS drop ahead...?
Best Regards,
Kuramochi