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How accurate is the temperature sensor in the AD7689?

Question asked by cchipman on Jan 8, 2013
Latest reply on Feb 19, 2014 by maithil

I have an AD7689 that I am using to monitor temperature in addition to voltages. Right now, in a 22C room, I am reading the temperature from the AD7689 to be 2C. Is there a calibration needed?


I am reading my voltages correctly, so the ADC is in good shape. I am getting readings of around 2C for all three AD7689s I have used.


The configuration word being used is 0xB160, that is,

1: overwrite config register

3: read temperature

0: don't care channel

1: full bandwidth

3: ext. ref., int buff, temperature enabled

0: disable sequencer

1: no read back

all shifted up by two.


The value I read from the ADC is then converted to mV referenced to a 3.3 external reference with 65536 bits of resolution. The temperature is then calculated with  25C at 283mV offset by the ADC reading. That is, temperature = 25C + ((reading -283mV)/1mV/C).


Thanks for any help.