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TLV2171: Abnormal voltage reading in min voltage detector circuit to replace TL082

Expert 4170 points

Replies: 4

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Part Number: TLV2171

Hi Expert,

We are replacing commodity TL082 by using TLV2171 and meet an issue in min voltage detector circuit.

Could you please help to check whether there is any problem for circuit by using TLV2171? Attached schematic implemented by TINA:

TLV2171 Valley detector.TSC

The key difference by using TL082 and TLV2171 is:

By using TL082:

Vout: 0.24V

Vin2: 1.9V

V-: 0.24V

V+: 1.9V

By using TL2171:

Vout: 0.24

Vin2: 1.59

V-: 0.31

V+: 1.47

In TLV2171 datasheet, there are internal diode at the input pins. Are these difference between TL082 and TLV2171 in min voltage detector circuit caused by these diode?

Thanks.

Zhou

  • Hello Zhou,

    For an op amp to operate as a comparator the op amp cannot have internal input clamping diodes (back-to-back diodes). I recommend taking a look at the OPA191 or OPA196 for a high voltage op amp that does not have internal input clamping diodes. Or the TLV9062 or the TLV9002 for low voltage operations.

    Thank you,

    Tim Claycomb

  • Hi Zhou,

    V3, V4, V6 and VS1 are confusing me. Are V3 and V4 reference voltages? But what is V6? And what is the input signal? Are there two input signals V1 and V2? But what is VS1?

    Kai
  • In reply to Tim Claycomb:

    Hi Tim,

    Could you please help to see whether this problem cause by internal clamping diodes? TL082 does not have internal clamping diode, right?

    Thanks.
    Zhou
  • In reply to Zhou Fang67:

    We did a verification to confirm that the problem is caused by internal diode.

    Thanks.
    Zhou

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