Understanding thermopile calculations

Other Parts Discussed in Thread: LMP91051, TMP006, OPA320, TL431

I am using a thermopile sensor. Now i am able to measure thermopile mV & thermistor temperature. I was reading this document by TI engineers: https://www.fierceelectronics.com/components/demystifying-thermopile-ir-temp-sensors

Vasco Polyzoev & Habib Karaki

Now to get object temperature from it. Can some onehelp what is formula for it?

over 5 years ago

0 Josh Wyatt over 5 years ago

TI__Guru* 91206 points

Dear Vasco and Habib -

Are you using the LMP91051 (see page 17 here where its described, and shows older way with discrete op amps, then using the AFE) https://www.ti.com/lit/ds/symlink/lmp91051.pdf

0 MI over 5 years ago in reply to Josh Wyatt

Intellectual 560 points

I am using this sensor. able to measure thermopile mV and thermistor resistance/tempearture.

Which formula is correct or given in Page 17 of LMP, but its for gas detector , we use using IR thermopile.

OTP-638D2_datasheet(R(0) and application(0-50).pdf

0 MI over 5 years ago in reply to Josh Wyatt

Intellectual 560 points

I am using this sensor. able to measure thermopile mV and thermistor resistance/tempearture.

Which formula is correct or given in Page 17 of LMP, but its for gas detector , we use using IR thermopile.

6305.OTP-638D2_datasheet(R(0) and application(0-50).pdf

0 Josh Wyatt over 5 years ago in reply to MI

TI__Guru* 91206 points

Dear MI -

sorry for mis-identifying you earlier -

that article was based on a device TMP006, which we discontinued.

In this case, since you aleady picked out your sensor, and this device already puts out mV (vs. uV expected by the LMP91051 that i asked about before) I will point you to section 5 of the datasheet you provided for the sensor you are using - they have a circuit that you can recreate using op amp, a precision shunt regulator (the one they call out in their datasheet is NRND) and some resistors, feeding two ADC channels on your MCU. Looks like everything you need is in this datasheet.

from the TI portfolio, you can use MSP430 or MSP432 for MCU with ADC, TL431/432 for the regulator (or similar, to replace AP432N) and OPA320 (or similar) for the opamp.

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Understanding thermopile calculations