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LOG114: problem

user4645094
Prodigy 210 points

Part Number: LOG114

Dears，

Pin 12 and pin 13 have the same voltage, and pin 14 and pin 15 have the same voltage

When the voltage of pin 12 and pin 13 is 3.55v, the voltage of pin 14 and pin 15 jumps to 4.99v

Now, 6 chips are tested, and 2 of them can follow, but the voltage has a deviation of a few tenths of a volt. The other 4 chips jump to 4.99v after exceeding 3.55v,

Theoretically, the voltages of the four pins 12, 13, 14, 15 are the same

But the actual situation is not，Please kindly help  analyze the possible reasons. Thanks!

  • 0
    Guru 140200 points

    Hi,

    you violate the common mode input voltage range. The input voltage must stay below (V+) - 2V = 5V - 2V = 3V.

    Kai

  • 0 in reply to kai klaas69
    TI__Guru 55466 points

    Thank you very much Kai,

    Hi User,

    The op-amp A4 and A5 input common-mode voltage range (VCM) is delimited by the supplies.   

    When the device is powered with ±5V supplies, the op-amp A5 VCM limit is from (V-) to (V+)-2V:   

    The op-amp A5 input common mode voltage range is limited from -5V to +3V, while powered with ±5V supplies. Therefore, when applying a voltage of +3.55V to pin 13 (+IN 5), op-amp A5 is outside its input common-mode linear range.

    Please let me know if you have additional questions,

    Thank you and Regards,

    Luis