I'm not using USB nor ADC/DAC on the STM32MP157A. Can I tie VDDA, OTG_VBUS, AND VDD3V3_USBxS to circuit ground (VSS)?

[JCond.1]

If I'm interpreting Table 13 correctly (datasheet p 128), VDDA can be set to 0 volts provided VREF is not used. Similarly power pins related to USB can also be set to 0 volts. Looking in the datasheet p29,I just need to star-connect VDD_ANA, VDD_PLL and VDD_DSI to VDD, and make sure that VDD powers up before VDDCORE. Would this be alright, have I missed any important details?

[Tesla DeLorean]

Isn't VDDA involved with the PLL and POR?

[JCond.1]

From what I read, that is correct for STMF030R8. However, the STM32MP157A has a dedicated Vdd_pll pin. I'm not 100% on the POR, but the block diagram says Vdd_ana is involved with supply supervision.

[PatrickF]

Hi,

note that without USB on your platform, your loose fast way to program the system flash using CubeProgrammer (which for MPU devices could use USB or UART, but not JTAG).

USB (OTG device) could be also useful for debug/SSH your target using Ethernet-over-USB in case there is no ethernet connector on your product.

Your conclusion seems ok for me.

here is a summary (bold as preferred):

If USBH and OTG are not used

• VDD3V3_USBHS, VDD3V3_USBFS: left open or tied to VSS
• VDDA1V1_REG: left open
• VDDA1V8_REG: left open (only if DSI interface is not present or not used)

If ADC/DAC/VREFBUF are not used

• VDDA: left open or tied to VSS or VDD
• VREF+: open

I also recommend to look at AN5031 which give some guidelines for HW.

Regards.

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