Post Go back to editing

offset problem of AD8629 OPAMP

Dear Sir/Madam,

Our customer have met one trouble as following.

(This discuss came from another sled cause my miss understood)

On my enclosed schematic Fig-1.pdf,

step-1 power off and keep waiting around 30 sec

step-2 power on

step-3 around 90msec offset voltage appear at out-1 pin

step-4 power off and on but the 90mV offset is not cleared

Also refer to my enclosed time chart "tme chart when power off and on.pdf".

note

*1 ; 30sec is not certainly.

*3 ; in some cases, it return to expected value

After once this trouble happen, out-2 is up and dowm on offset voltage 900mV(x10 gained value)

 

When we work with above action, does your AD8629 do such a motion?or not.

If he replace the thermopile(TP) to fixed resister 175kohm, then the result was same.

Please advice us before your holiday!!

Thank you in advance Kaos

attachments.zip
Parents
  • Hi, Chard

    Very sorry to my late response  to here.

    Here is customer response.

    After power off, the offset voltage doesn't remain there.

    Customer tried to make change R35 from 1.3Mohm to 130kohm, but the offset voltage still remain there.

    After around 20 sec, there is not the offset voltage  so return to expected value in some cases.

    Sorry not never return I correct this.

    So again customer explained this trouble.

    In some cases, there is the offset voltage become plus 90mV than expected value

    when the stable condition after power on.

    After power off , the output of Amplifier (the offset voltage )fall to 0V.

    After around  a couple of minutes

    , then the offset voltage fall the offset value become plus 90mV than expected value.Si the plus 90mV value is kept to power off. But this appear sometimes. Not always.

    Any Comment?

    Thanks Kaos

Reply
  • Hi, Chard

    Very sorry to my late response  to here.

    Here is customer response.

    After power off, the offset voltage doesn't remain there.

    Customer tried to make change R35 from 1.3Mohm to 130kohm, but the offset voltage still remain there.

    After around 20 sec, there is not the offset voltage  so return to expected value in some cases.

    Sorry not never return I correct this.

    So again customer explained this trouble.

    In some cases, there is the offset voltage become plus 90mV than expected value

    when the stable condition after power on.

    After power off , the output of Amplifier (the offset voltage )fall to 0V.

    After around  a couple of minutes

    , then the offset voltage fall the offset value become plus 90mV than expected value.Si the plus 90mV value is kept to power off. But this appear sometimes. Not always.

    Any Comment?

    Thanks Kaos

Children
No Data