AM2432: ADC power issue

Hello Hang, 

Thank you for the query.

Are there any inputs connected to the ADC inputs.

Can you verify the amplitude of the inputs. 

Please note that the ADC inputs are not fail-safe.

In case the ADC inputs are available before the SOC supply ramps, you will have to disconnect the inputs and test.

Regards,

Sreenivasa

Hi Sreenivasa,

There are four ADC inputs on the board, the unused ADC pins are pulled down. As they try to locate the issue, three ADC inputs are disconnected and only one remains, which has 1.338V voltage when PMIC fails.

When they decrease the ADC input to 0.7V, PMIC is functioning normally.

What does "not fail-safe" means? Is it necessary to make sure ADC input is zero when booting?

Regards,

Hang.

Hello Hang, 

Thank you.

Hang Yang said:

When they decrease the ADC input to 0.7V, PMIC is functioning normally.

Good to hear you see the issue.

Hang Yang said:

What does "not fail-safe" means? Is it necessary to make sure ADC input is zero when booting?

Please refer below. In this use case, the ADC inputs should be applied only after the SOC supplies ramp. Alternatively, you need to switch the ADC input after the supply ramps.

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1300808/faq-am625-am623-custom-board-hardware-design-power-sequencing-between-soc-processor-and-the-attached-devices-fail-safe

,Regards,

Sreenivasa

Hello Hang, 

Hang Yang said:

three ADC inputs are disconnected

I assume this is for testing. In case these ADCs are not used in the application, it is recommended to pulldown the unused ADCs.

Regards,

Sreenivasa