What should I do with STPMIC1 unused pins ?

[CharlesBlanchard]

Hello,

I'm designing a board based on STM32MP1 and we decided to use the STPMIC1A to manage the power. The board is really simple and so we use only the bucks (1 for core, 2 for ddr, 3 for vdd and 4 for extra 3.3).

All others (LDOs; boost and switches) are not used. We do not use termination for the DDR3 and the Vref is generated in another way. My intuition would be to connect input to ground and output left open. Am I right?

Also, is it necessary to deactivate them by I2C to reduce the power consumption of the chip?

Regards,

Charles

[MBENI.1]

Hello Charles,

yes you are right. You can connect to GND the input pins of the IPs which you are not using, and you can leave their respective outputs floating.

By the way you can refer to the attached image for every PIN setting. The only constrain is related to the input of BUCK1 (pin 8) and BUCK2

(pin 12): this pins, have to be always connected to VIN (to ensure the LDO functionality), even if these BUCKs are not used.

For the IPs you are not using, I suggest you to disable them by I2C interface.

Best regards,

Maurizio

[CharlesBlanchard]

Hello Maurizio,

Thank you for your precious help. At first I thought I missed something in the datasheet but I can't find this table so I'm reassured.

Once prototypes will be produced, I will see if the best solution is to

• put not used LDOs to rank 0 in NVM (NVM_LDOS_RANK_SHR2) to not start them at power-up
• use the LDOx_MAIN_CR but need to be done at each start-up

But I saw that for DDR Vref and power switches, it is not doable from NVM so solution 2 might be the best.

Best regards,

Charles