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AD7193 Temp measurement in unipolar mode.

I am using a channel on the AD7193 in unipolar mode. I want to add a temp measurement to the channel sequencer (i.e. enable the channel sequencer and add the temp channel).

When I do this, I get very strange data, especially given the equation in the datasheet. I get a conversion result around

1,664,466 or


0x19 65D2

This is well below the 0x80 0000, 0 Kelvin point.

I am guessing this is due to the unipolar vs bipolar operation, but if so, what should my offset be? Is the voltage really supposed to read 0 if we are at 0 kelvin in unipolar? If so, then using my above numbers, the chip is at 318 degC.

Is the offset somewhere around 0xC98FC, which is what it would have to be to give me a room temp reading? This is almost 50% of the current readings I get.

I have tried this on 2 boards that this chip is on, so it is not isolated to a single chip. Its also interesting to note that the temp does respond as expected. I can watch the chip rise a few degrees just after being turned on.