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  • TI Thinks Resolved

OPA2348: The output issue from OPA2348

Intellectual 1685 points

Replies: 2

Views: 47

Part Number: OPA2348

Hi Experts:

I found an issue of OPA2348 in customer's system , see the schematic attached . The input from CON1 is the signal generator,

The gain is 1000V/V, we input the 2mV and 66HZ sine waveform ,the output signal is only 1V , which is not correct.

I also check the bandwidth gain and think it should be OK for the 66HZ input, and i also do the simulation in the TINA, It also OK .

So could you please tell what's wrong with it , is it the Vos issue ?  

If some parameter of the OPA2348 can't support this case, is there any device you recommend? 

IC2-A.TSC

  • Hello Jason,

    I think you have the wrong gain set up with your resistors.  Currently, you have 100MOhms in the feedback and 100Ohms before that.  That will give you a gain of 1,000,000V/V.  Was this intended?

    Regards,

    Daniel

  • Hi Jason,

    the chosen gain is way too high. The OPA2348 shows a maximum input offset voltage of up to 6mV. This would result in an output voltage of 6mV x 1000 = 6V (without the diodes in the feedback loop). So, even the least offset voltage will make the diodes turn on.

    Kai

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