ADUC824/834 microconverter's temperature sensor

Document created by analog-archivist Employee on Feb 23, 2016
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Can you please supply the specification for the on-board temperature sensor on
the ADUC824/ADUC834 devices? I need an accurate description of the temp
channel. This doesn't appear in the datasheets. I suspect it might be a biased
diode of some sort but really need to know the details.

 

Only typical values are specified in the datasheets (specified typ. accuracy
+/-2degC). The on chip temperature sensor is not well characterised. It’s not a
problem with the reference or the temp sensor, we use a standard “Brokaw” cell
bandgap reference for both the reference and the temp sensor, we simply have
not fully tested for max and min values. This would have added too much test
time and increased the cost of the overall chip. Instead we give typical values
for the temco and temperature at 25degC. You can typically achieve an accuracy
of 2 or 3 degrees if you calibrate the temp sensor using the ADC. Many
customers are using this temp sensors to give an indication of significant
changes in temp (10 to 20 degC) increases and then adjusting calibration
co-efficients accordingly.

Note: For all microconverters, the temperature measured is the die temperature,
not the ambient, so you need to know the thermal impedance (specified in
datasheet)and the power dissipated by the ADuC to determine ambient
temperature.

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