LMP91051: LMP91051 issue need help

Darren,

To address your questions below:

Address 0x0 and 0x1 are Device and DAC configuration registers and the bit selections are described on page 16 of the datasheet.

Pins A0 and A1 change the signal path and allow for external filtering of the thermopile signal. The external filter (low, high or bandpass) is configurable by the resistor and capacitor you choose. However, for the reference design, the external filtering is not needed. 

It is recommended to add the buffer to the output of the thermistor. The amp is able to drive the RC filter and ensure the RC works as intended. The ADC may not behave well without a good driver/RC. 

I am not quite sure I understand your question about the CMOUT pin? Can you explain further?

For the best time to sample AD after switching channels, aim to have the sampling synced to the lamp pulses to ensure data is being captured at the expected time. Sampling Rate = Input Channel Mux Toggle Frequency (100 Hz) x Number of Ch. Samples per Ch. Toggle

For reference, please see the LMP91051 NDIR C02 Gas Detection System Application Note as well as use the WEBENCH tool for device configuration located on the right side of the product folder page. 

Jalen

Hi  Jalen

But it's not clear how to calculate the difference in concentration based on the waveform. Is there a simple example on your side?
Is it the same as the picture below, I only sample the waveform data of points A and B, and the difference is used as the effective value of the calculated concentration?Or is it according to other methods?

Hey Darren,

Yes, it is calculated as such. This is explained in the application note below:

You'll want to characterize your sensor at both low and high ppm to determine the slope as well.

Jalen