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TLV2374 Absolute Maximum question for VDD and Vout

Jake Kim
Intellectual 680 points
Other Parts Discussed in Thread: TLV2374

I have another question about VDD pin.

1. How much negative voltage VDD pin can endure?

In the datasheet, VDD is only 16.5V with respect to the GND pin.

What about negative input on VDD with respect to the GND.

2. How much negative voltage can TLV2374 endure on Vout pin?

Hope to see prompt answer.

Thanks

  • 0
    Expert 1220 points

    I guess the question would be, "Why are you asking?"

    Is this a proposed fault condition on a new design? If so, I would completely avoid it. Protect the part instead.
    Is this a fault condition caught on the first revision of the board? I would add protection and re-spin the board.
    Is this a fault condition occurring on an existing design in the field? Offer a band-aid fix and then re-spin the board.

    From my knowledge, op-amps are not intentionally designed to handle reverse polarity across the power supply pins. I am sure there are a few hundred mV with a few mA of current that the device could withstand and not degrade the part, but I am pretty sure no manufacture will want to warranty the device since the datasheet clearly says ABS MAX.

    Since this is a CMOS part, any forced voltage on the output part will be limited to, generally speaking,  600mV above OR below the supply. What will happen is that you are biasing the internal ESD diodes on the output.

    -Ken

  • 0 in reply to Ken Dillinger
    Intellectual 680 points

    Hi,  Ken

    As you said, I wanted to know the ABS spec to protect OPAMP.

    If you have, Would you share a application note for protecting OPAMP?

    Thanks for the great support

  • 0 in reply to Jake Kim
    Expert 1220 points

    You could put a simple diode in series with the power supply pins. Cathode to the VDD pin and Anode to the offending reverse battery. 

    Under normal operation the op-amp will see a diode drop, so be prepared for the loss across the diode. Maybe a Schottky for a lower drop, maybe the body diode of a FET (higher expense), 

    -Ken

  • 0
    TI__Guru* 93105 points

    Hello Jake,

    1. How much negative voltage VDD pin can endure?

    Intergrated circuits in general are not intended to be subjected to reversed supplies. Most integrated circuit structures have a substrate diode, or something equivalent to a substrate diode, that exists between the VDD and GND pins. This diode is normally reverse biased when the circuit is powered normally, but will become forward biased when the supplies are reversed. Once the forward bias increases beyond about a half a volt the diode conducts higher and higher current as the voltage across the diode is increased. If the voltage becomes too high the diode will conduct so much current that the integrated circuit is damaged. The diode isn't characterized for this type operation and one should avoid it.

    2. What about negative input on VDD with respect to the GND.  How much negative voltage can TLV2374 endure on Vout pin?

    The TLV2374 inputs and output have ESD steering diodes connected from each of them, to each supply. They are reverse biased in normal operation. If you attempt to drive these pins below GND, they will become forward biased and draw higher and higher current as the forward bias is increased. Again, this is something you should avoid. The data sheet limits the voltage to 200 mV beyond the supply rail voltages.

    Regards, Thomas

    PA - Linear Applications Engineering