AM4372: RTC power consumption

Gush Bhumbra

Part Number: AM4372
Other Parts Discussed in Thread: TPS65218

I am using the TPS65218 PMIC to power the RTC on the AM4372 on our custom board. I was surprised to see the PMIC draw 160uA when powering the 1.8V and 1.0 RTC rails. What current should I expect the PMIC to take while supplying the processor? The circuit is the same as the GP-EVM, as far as I can tell.

over 8 years ago

0 Biser Gatchev-XID over 8 years ago

TI__Guru**** 393215 points

The factory team have been notified. They will respond here.

0 Gush Bhumbra over 8 years ago in reply to Biser Gatchev-XID

Prodigy 200 points

I have noticed that the 1.8VD rail from the PMIC is not at 0V but slowly rises to 0.2V. As this rises the current consumption from the 3V coin cell drops from 200uA to 160uA. If I short the 1.8VD output rail from the PMIC to GND, the consumption rises again to 200uA. The 1.8V_RTC and 1.0V_RTC are correct. All the other output rails from the PMIC are 0V. I have previously submitted our schematics to Biser. I did try changing the RTC_KALDO_EN pin on the AM4372 at 1.8V and GND and the current consumption does not change.

0 Gush Bhumbra over 8 years ago in reply to Gush Bhumbra

Prodigy 200 points

I also disconnected the AM4372 power rails from the 1.8VD line and the PMIC (TPS65218B1RSLT) continues to increase the 1.8VD output rail to over 1.0V and the current consumption from the coin cell continues to decrease to 70uA.

0 Gush Bhumbra over 8 years ago in reply to Gush Bhumbra

Prodigy 200 points

I have tried this on 6 boards. Two consume 200uA immediately after power down from the 3V coin cell. 2 consume 90uA immediately after power down. All six boards are the same hardware.

Is there anyone able to help please?

0 Biser Gatchev-XID over 8 years ago in reply to Gush Bhumbra

TI__Guru**** 393215 points

Sorry about this delay. I have escalated the request.

0 Gush Bhumbra over 8 years ago in reply to Biser Gatchev-XID

Prodigy 200 points

I worked what the issue was. I had copied the rev 1.4 schematic of the GP-EVM437x eval board which has a pull up resistor from PGOOD_BU to V1.8D. This pin is a push pull not open drain and ends up feeding the LDO1 output (V1.8D) rail. When this resistor is removed the current draw drops to a more acceptable 4uA.

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AM4372: RTC power consumption