I want to decrease the power consumption of LIS2DW12. It proposed to sense human motion, and I don´t know if it is better to have a Low Pass Filter or High Pass Filter configured in CTRL6, and what LPM mode I should set in CTRL1. Please see details below:

JGonz.1 · ‎2019-12-12

Actually our device has 33 uA in DC current consumption without accelerometer LIS2DW12, with the LIS2DW12 this previous number increases to 55 uA.

I think that it is possible to decrease the current consumption, based of the information of datasheets.

For more info, before having 55uA, we had 70 uA becouse we didn´t sleep it with the SLEEP_ON of WAKE_UP_THS (in both cases it is detected an interruption onf INT1 with no problems)

Thank you in Advance!

Best Regards

Jorge

Eleon BORLINI · ‎2019-12-13

Hi @Jorge González , which is your target current consumption? Please note that the settings of the filters don't impact the overall current consumption... Two ways to save power can be supply the part with low Vdds (e.g. 1.8V) or go to low ODR (and in low power mode, e.g 100Hz mean 5uA). The wake up feature is also a good way to reduce the average consumption so that you can run continuous mode during the standard data acquisition. Regards

JGonz.1 · ‎2019-12-16

Hi Eleon. Actually our devices has a current consumption of 35 uA without activati I2C bus and the Accelerometer.

With the Accelerometer the current consumption goes up to 55 uA.

Actually we have it Low Pass Filter, Low-Power Mode 1 (12-bit resolution), Low-Power mode 200 Hz ODR, but setting ODR to low value (like 100 Hz or 1.6 Hz doesn´t have impact of the consumption. CTRL1 (20h)

We use the 6D recognition is routed to INT1 pad of the CTRL4_INT1_PAD_CTRL 23h (may be there is a lower power mode to sense continuous motion.

ODR/2 bandwidth, FS +/- 4g, Low-Pass filter, Low Noise CFG disabled in CTRL6 0x25

Disabled stationary detection/motion detection with no auto ODR change/ sleep mode duration 16/ODR

All datas obtained from:

https://www.st.com/resource/en/datasheet/lis2dw12.pdf

The option about using a lower Vdd is unfeasible because it would make the PCb and the device more expensive.

I don´t know if there is a better configuration on the accelerometer.

Thanks for your previous anwser

Eleon BORLINI · ‎2019-12-16

Hi @Jorge González , in these conditions but with Vdd=1.8V, the accelerometer current consumption should be around 10uA (so 35uA+10uA). If Vdd is 3.3V, the supply cons becomes of course bigger, and closes to 16-17uA, which is a value similar to yours... It is very strange however you don't face a current reduction in case you reduce the ODR, you should: can you check if your I2C settings are effective using an oscilloscope on dataout, verifying the ODR variation? You can also try to reduce the I2C communication speed to e.g. 50kHz or less...

Regards