DK1 board consumes 45ma in complete power off state!

[VRoma.2]

Hi.

My STM32MP157A-DK1 board ​while in power off state without any connections consumes 45 ma of current.

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How could i reduce such a big amount?

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​Could it be ST-LINK power drain, or is it STUSB1600?

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What could i do to reduce the current to its minimum in poweroff or standby modes?

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Regards,

Vlad.​

[PatrickF]

Hi @VRoma.2​ ,

the DK1 board is not optimized for low power, there is still some component powered (STLINK, etc..).

See https://community.st.com/s/question/0D50X0000BB2xkBSQR/st32mp157cdk2-low-power-operation

https://community.st.com/s/question/0D53W000014WCrASAW/how-to-disable-the-stlink-from-stm32mp157dk1

If you are seeking for power consumption value, please refer to product datasheet (e.g. DS12504 for STM32MP157A or D) as well as AN5284 (note that this AN was using old ecosystem SW, so Linux commands might have evolved, as well as power results which has sometimes been optimized on latest Ecosystem).

Note that as per license agreement, development boards are not suitable for building a product (e.g. boards are not resalable and ST does not guarantee long term availability).

Unless you are just prototyping/evaluating, if you are not willing to build your own PCB, you could probably find more suitable modules on 3rd party vendors (e.g. partners, but not limited to).

Regards,

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[VRoma.2]

Hi PatrickF (ST Employee),

Thanks for advice, i've updated board to latest 3.1 release and checked again.

ST-LINK consumes about 35ma, and it seems better way to fix it is to remove D1 diode to make the link be powered via USB cable only.

Another interesting observation - the board drains more power without ethernet cable connected, than with it.

For example: 250ma without the cable (link down), and only 225ma with the cable (link up).

Are you guys didn't enable PHY's power saving? RTL8211F supports Link Down power saving, which should greatly reduce the power consumption while the cable is absent.

Regards,

Vlad.

[PatrickF]

Hi,

thanks for the details.

I remind that STM32 development boards are not a final product and are usually not optimized for power.

Development boards are provided to customers specifically to do this kind of trials by their own.

There is probably some (many) HW and SW modifications to get better power consumption.

If you are doing a product where power is important, you should rely on existing datasheet and build your own optimized HW and SW. For you information, we have some of our customers doing battery powered products with STM32MP1 (but usually not with an Ethernet cable !).

I'm more HW focused, so, I could give some answer for STLINK power.

Populating SB18 with a 0 ohm will keep the embedded ST-Link in reset, thus reducing it's consumption to minimum . There will be no way to debug nor use USB Virtual Comm port thru CN11.

0 ohm on SB18 has no side effects, but will not completely remove ST-LINK power consumption.

Removing D1 or SB21 might need to remove SB22 as the un-powered ST-LINK might drop the NRST to low level. This is non-tested option, maybe there is side effects. as previous option, there will be no way to debug nor use USB Virtual Comm port thru CN11.

Btw, some other non-tested options, if you are eager to do some tricky wiring.

It might be possible to connect SB18 to PWR_ON with a diode (K on PRW_ON side) to automatically maintain STLINK in reset during Standby mode (similar to SB18).

Another option might be to connect INH pin of U34 to PWR_ON du disable STLINK supply (similar to D1 or SB21). PWR_ON might need a pull-down to ensure working in OFF mode too.

But I repeat, this is not tested, some drawback might occur.

Regards.