LIS2DTW12 Power Down question

[vard]

Hello Everyone!

I am working on an application where I have to read the temperature sensor once every minute, and I would like to put the sensor in power down mode when I don't need to read the temperature.

Details:

1) I am using an STEVAL-MKI190V1 board

2) I am measuring the the current on VDD only (VDD_IO is connected directly to 3.3V) with an STLINK-V3PWR board set at 3.3V out, and the STM Cube Monitor Power software.

3) I am controlling the eval board via an STM32L011K Nucleo board

4) Communicating via SPI, 4 wires, nothing else attached to the eval board (other than power and gnd, of course).

5) I am using the MEMS1 drivers

6) I've turned off the pull-up resistors on CS and SDO, but that doesn't really matter because I'm measuring the current on VDD only.

So I tried to put the sensor in power down mode by writing a 0x00 in the CTRL1 register, to set ODR to power down, MODE to low power and also LP_MODE to LP mode 1, and I was expecting some 50nA of current, but instead I'm measuring about 450nA, almost ten times higher current.

Any suggestions are very much appreciated!

Thank you!

Vlad

[Federica Bossi · Accepted solution]

Hi @vard ,

Welcome to ST Community!

I think there is something wrong with your setup, this is my measurements using LIS2DTW12 and STEVAL-MKI109V3 and I confirmed what we declare in datasheet:

Please check your connections and layout.

[vard]

Hello Federica,

Yes, I had a problem the the setup. I've also ordered the steval-mki109v3 and I will repeat the measurements, but I am pretty sure that the problem was with my setup.

Long story short: I used an STLINK-V3PWR board and the STM32CubeMonitor Power GUI to measure VDD, and it  turns out that in dynamic mode, the resolution of the STLINK is not low enough for these kind of measurements. 

I've already repeated the measurements using a X-NUCLEO-LPM01A board set in static mode, and I am getting IDD numbers very close to yours.

Thanks again for your reply!

Vlad