Steval-STWINKT1B - Where is all the power going?

LWeir.775 · ‎2021-09-08

On the STEVAL-STWINKT1B board, and using the HSDatalog firmware, it uses about 60mA in idle state. I have disconnected the sensors, and the uC, and turned off the SD card power lines, but it's still at around 2mA. Does anyone know where this power is going? Ideally, I want to create an application for the board when it wakes up for 1 minute in every hour, logs the data to the SD card, and then goes into a nearly dormant low power state to preserve the battery.

Eleon BORLINI · ‎2021-09-09

Hi @LWeir.775 ,

In the current design, unfortunately, the 2.7A regulator cannot be switched OFF, so also the connected OpAmp is always ON.

The only option would be to de-solder it, or de-solder the OpAmp which accounts for more than 1mA alone.

If my reply answered your question, please click on Select as Best at the bottom of this post. This will help other users with the same issue to find the answer faster.

-Eleon

View solution in original post

Eleon BORLINI · ‎2021-09-09

Hi @LWeir.775 ,

In the current design, unfortunately, the 2.7A regulator cannot be switched OFF, so also the connected OpAmp is always ON.

The only option would be to de-solder it, or de-solder the OpAmp which accounts for more than 1mA alone.

If my reply answered your question, please click on Select as Best at the bottom of this post. This will help other users with the same issue to find the answer faster.

-Eleon

LWeir.775 · ‎2021-09-09

Hi Eleon,
That was our prime suspect. Thanks. It is frustrating given what we want to use the board for. I think we are going to try and reconfigure the power supply to the 2.7v LDO such that it comes from DCDC2 instead, and so is switchable. Not an easy mod and frustrating the board doesn’t have it as a configuration option.

Eleon BORLINI · ‎2021-09-10

Hi @LWeir.775 ,

The DCDC converter provides the supply the microphone, so this would be the only component that would be excluded removing the LDO.

We are however designing a rev2 platform, and we will take it into account this issue.

-Eleon

LWeir.775 · ‎2021-09-10

OK. That makes sense. Unfortunately the microphone is key to our project. What are the current project timescales for release of a rev2 board?
Laurence

Eleon BORLINI · ‎2021-09-10

Hi Laurence,

I cannot disclose a precise timeline for this application, but it will be in the next months.

-Eleon

LWeir.775 · ‎2021-09-10

Good to know.
We have also found in the release software the size of the memory allocation at startup causes the SD card to crash when coming out of idle state. If that is fixed, as well as enabling a very low current when idle mode, it will save us a lot of time in our development schedule.
Thanks again,
Laurence