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AD8495 behaviour problems

Question asked by medEng on Dec 1, 2015
Latest reply on Dec 18, 2015 by medEng

Hello!

 

Recently I have been assembling thermocouple sensors using the AD8495, while sometimes functioning excellently I have been having trouble consequently assembling functional PCBs due to what seems to be a problem with the AD8495 circuit. The main issue is that the output at pins 5 and 6 is randomly very close to the bias voltage (5V) instead of expected 0.27V.
My circuit follows the guidelines specified in the datasheet and is relatively simple, eliminating most other possibilities.

 

During the troubleshooting process I have encountered some other common issues;

 

* Pins 2 and 3 seem to sometimes be internally shorted, either giving straight up short-circuit or transient behaviour.
* The circuit has high currents mA-muA exiting and entering pins 1 and 8. This occurs under conditions where the output is faulty as well.

I am looking for advice on assembly of the circuit and any information on its overall function which is not mentioned in the datasheet.

Is it very temperature sensitive? (I need to take special caution when soldering).

Is it very sensitive to mechanical stress such as tweezers?
Is the output permanently damaged if it produces voltage of 5V?

Looking for any constructive comments and help!

 

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