i2c address selection leakage current with 2 x LIS2DW12 on one PCB

JasonRrrr · ‎2024-04-11

I want to use 2x LIS2DW12 accelerometers on one PCB.

I used i2c to save GPIOs.

The i2c address is selected by pulling the SDO/SAO pin HIGH or LOW and it is internally pulled HIGH with approximately 20kohm at 3.6v.

If I just connect it to GND then I can expect 180uA leakage.

If I use a resistor to pull it down then I calculate that to get a LOW value of 0.2 x 3.6v (0.72V) I need to use a pull down of at least 5Kohms. But this implies a leakage current of 146uA. Which is still not great.

Is there another way to connect 2 x LIS2DW12, except using SPI?

Can I connect the SDO/SAO to a GPIO and toggle it LOW when I want to read either accelerometer, and leave it floating the rest of the time? (pulled high)

Federica Bossi · ‎2024-04-30

Hi @JasonRrrr ,

Yes, it is possible to toggle the SA0 by GPIO to have the LOW-Address only for the sensor read. But the other sensor address should be HIGH and not floating.

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