Difficulty Putting LSM303AGR to Sleep

[Jason Wilbee]

Posted on August 01, 2017 at 20:37

Hello,

I am attempting to integrate the 

https://community.st.com/tags♯/?tags=lsm303agr

 into an existing product and I am having difficulties bringing down the power consumption of the LSM303AGR to reasonable levels. As I understand it, the module should be consuming only around 3uA or so when idling, but I am seeing more like 300uA, which seems to be inline with power consumption while the magnetometer is taking measurements.

The steps I am taking to put the device into sleep mode are clearing the ODR[3:0] on CTRL_REG1_A which the datasheet indicates should put the accelerometer in power down mode and setting bits MD[1:0] in CFG_REG_A_M. After writing to these registers I read them back to confirm that the changes occur. For reference I am communicating with the module over I2C.

Are there any known bugs with sleep mode or possible gotchas that could be responsible with the issues I am seeing?

Thanks,

Jason

#sleep-mode #lsm303agr #lowpower-sleep #sleep

[Miroslav BATEK]

Posted on August 03, 2017 at 14:00

There is no bug with the sleep mode.

Can you please measure the current consumption before you configure the sensor? The sensor starts-up in power down mode so you can check the current consumption in this mode. If the current after start-up is not as expected, there could be some additional current caused by pull-up or pull-downs, it this case I would need to check zour schematic.

[Jason Wilbee]

Posted on August 03, 2017 at 19:50

I have tested both with my hardware configuration and with an MKI172V1 eval kit. On the eval kit I am only hooking up VDD, VDDIO, and GND and with an input voltage of 1.8V(on VDD and VDDIO) sleep mode seems to work, however, running the part at anything above that like 2.5V or 3.6V I see a high idle current like I mentioned above.

[Miroslav BATEK]

Posted on August 14, 2017 at 11:24

If you share your schematic I can check it.