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TLV9352: Is negative V- is acceptable for application?

Nanxiao Zhong
Intellectual 1710 points

Part Number: TLV9352
Other Parts Discussed in Thread: TL082H, , LM7705

Hi Team

As the schematic shows, when V+ is connected to gnd, V- is a negative voltage(-1mV to 0.7V). Will it be damaged in this situation? Since the datasheet suggest that V- should be above Vcc- -0.1V, and common voltage range is minimum Vcc- -0.5V. In experiment, the output is same as theoretical calculated value.

Thanks a lot.

  • +1
    Guru 325520 points

    Above (V−) − 0.5 V, there will be no damage.

    Below (V−) − 0.1 V, the electrical characteristics are no longer guaranteed. I suspect that only AC characteristics change, but there is no guarantee.

  • +1
    Guru 140200 points

    Hi Nanxiao,

    the schematic is showing the TL082H. Has your question to do with this thread

    https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/1170914/tl082h-application-of-input-voltage-range

    and you want to replace the TL082H by the TLV9352?

    The above circuit may work, if you apply the -0.7V input voltage after you have fully powered-up the OPAmp. But if you apply the -0.7V before the OPAmp is powered-up, latch-up can occur during the power-up. Latch-up can only be prevented, if the input voltage exceeds the supply voltages only minimally. +/-0.3V (better less) in combination with a current limiting resistor is said to be a safe method to prevent latch-up. Your -0.7V is too much in my eyes.

    Limiting the negative going input voltage by a Schottky diode (BAT54S, or else) and furtherly decreasing of input voltage by the help of a voltage divider (factor two or so) can do the trick.

    But the best remedy is to entirely prevent the input voltage from exceeding the supply voltages of OPAmp by using a bipolar supply voltage. Sometimes the use of LM7705 can help to add some headroom.

    Kai

  • 0 in reply to kai klaas69
    TI__Intellectual 1710 points

    Hi Kai

    Thanks a lot for your detail answer. Yes, because TL082H is not a rail to rail input amps, so I replace TL082H by TLV9352 which has better performance. The diode in fact is a Mosfet, for easy to understand so I replace it by a diode. Of course, when the Mosfet is off, the voltage drop is near 0.5V.