AD623 output need operation time for stable output?

* Schematic of AD623

* Output Voltage of AD623

When AD623 operate after powering on, AD623 has varied(unstable) output till a certain time.

After a certain time (about 30minutes), AD623 has stable output as below.

So System of AD623 has pre-operation time about 30 minutes.

Consequntly, AD623 should be handled pre-operation time for stable output?

Maybe, In my guess, AD623 need rise up to normal operation temperature  for stable output?

Parents
  • Howard,

    What are the red and blue traces?  Which 623??  top or bottom?

    Everything has a tempco.  If you want very stable operation, you need to use resistors that are 5-10ppm/C tempco,

    and get rid of the junk op amp, LM2904.  Do not use a dual.  You did not show what the other section is doing, but

    it can affect the section you are using.  Use a autozero op amp such as the AD8538, etc.  Also, if the 3.3V digital

    drifts, it goes through the pot into your signal chain.  Use an ADR3425 to drive the top of the pot.

    Can't see values on some resistors;  can you attach a good PDF??

    What is R44?  R39??

    Harry

Reply
  • Howard,

    What are the red and blue traces?  Which 623??  top or bottom?

    Everything has a tempco.  If you want very stable operation, you need to use resistors that are 5-10ppm/C tempco,

    and get rid of the junk op amp, LM2904.  Do not use a dual.  You did not show what the other section is doing, but

    it can affect the section you are using.  Use a autozero op amp such as the AD8538, etc.  Also, if the 3.3V digital

    drifts, it goes through the pot into your signal chain.  Use an ADR3425 to drive the top of the pot.

    Can't see values on some resistors;  can you attach a good PDF??

    What is R44?  R39??

    Harry

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