Will the LIS2HH12 operate properly with Vdd_IO = 0V and Vdd = 3.3V ?

[Michael Ray Canada]

We are looking at using the LIS2HH12 in a design where the connected MCU is powered off and the LIS2HH12 remains powered on. We plan to use the LIS2HH12 in I2C mode so CS will be High. Will cycling Vdd_IO from 3.3 to 0 to 3.3V generate spurious I2C signals?

Other questions we have are:

• Will the INT1/2 signal operate correctly when Vdd_IO = 0V? We want to use one of these signals to wake-up the MCU.
• If we set CS = 0V, will that reset the I2C logic in the LIS2HH12?
• There is a way through the registers to Soft Reset the LIS2HH12. Are there other ways to reset the I2C bus if it gets 'stuck'? Ideally, we do not want to put a separate power switch in for the LIS2HH12.

Thanks all for any answers or feedback.

[Eleon BORLINI · Accepted solution]

Hi @Community member​ ,

for the I2C High level definition (and for the digital features in general) you need the VddIO pin. In case you have not enough analog resources on your application processor, you can tie Vdd and VddIO together. The INTx pins need the VddIO too, but you might use a different Vdd than the MCU's one for the LIS2DHH12, in order to wake up the system.

-Eleon

[Michael Ray Canada]

Thank you Eleon!