Pressure sensor LPS25HB don't work properly when supplied from a coin cell in my design . Pressure values are wrong. It looks like an energy issue ... the sensor has not enough energy to work properly ?

[VLeme.2256]

Hello,

I made a new PCB design using the LPS25HB (see PCB prints attached). On this new PCB, the LPS25HB works fine when I put a new coin cell (I get correct pressure value to compute a height difference of 50cm so I use the sensor at its maximum performance). When the Voltage on the coin cell drop a bit (below 2.9V), the sensor give wrong pressure values ... It looks like the sensor can't receive enough energy to work properly. I can say that because when I put a new coin cell, it works again. Also, if I turn on LEDS (3mA drained from the coin cell) when the pressure sensor register values, values becomes incorrect (the led drain the power I suppose).

I use a regulator (MIC5232-2.8YML) between the coin cell and the pressure sensor. But I don't think the regulator is the problem because other components (accelerometer LSM6DSOX and my processor) work fine and are supplied by the regulator.

I don't understand why the pressure sensor behave like that because the datasheet say that the sensor can work above 1.7V and it's current consumption is in the order of uA (in my configuration). It should not need so much energy ... do you think it is an energy issue ? or is it maybe a design issue regarding my new design attached ? Maybe the current (order of mA) that flow through lines near the pressure sensor ? (there is 5 mm distance between so I don't think it should impact so much ...)

Can someone help me ? I am a bit confused ...

Waiting for your reply,

Regards,

Valentin

[Eleon BORLINI]

Hi @VLeme.2256​ , back to you in these quarantine period... I also believe with you that it is not an issue due to a lack of energy for the LPS25HB. You say that when the Vdd falls below 2.9V the LPS25HB . Are you measuring the effective Vdd that is supplying the LPS25HB? Are you working in SPI mode or in I2C mode? And which is the Vdd_IO value? Last, did you connect the reserved PIN 3 to GND as reported in the datasheet? Regards