Hi team,
My customer now uses LMP91050, but after they power on the device and write 0x0060 to device, the LMP91050 still stays 0 when signal voltage is 1mV. Please see the attached schematic and SPI waveform. Is there anything need to be changed? Thank you.
Dear Taoran -
in the schematic that was shared - it looks ok, however there is are components around the sensor which i cannot find that we recommend to place.
(their R1, R2, R3, C1)
then - it seems from the o'scope image that they are intending to write into register 0 and they are changing the gain from default to 32.
Based on the thermopile characteristics (they need to check this with vendor), select the common-mode voltage and gain to be programmed into the LMP91050. CMOUT should be selected to center the expected dynamic range of the thermopile within the full scale range of the ADC to the best extent possible.
The gain should be selected to maximize the signal range at the ADC input, but should allow some headroom below full scale to prevent clipping. The gain should also compensate, if possible, for any loss due to the filters in the signal path.
I would highly recommend they get the evaluation kit and refer to it while developing
LMP91050 eval board
user guide
code example
board to use with eval board for to PC/GUI
