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TLV2372 power supply unbalance

Jose Maroto
Expert 3230 points
Other Parts Discussed in Thread: TLV2372

Hi all,

 

TLV2372 is powered with  +5V and -5V power rails. Card is inserted in a rack and it could be the case someone extract the card without removing power. The +5V rail switches off quicker than -5V one, leaving TLV2372 only powered via the -5V rail during a few miliseconds.

 

Could TLV2372 get damaged under this circunstances? I am not sure if the -8V max. figure from datasheet page 8 (section 7.2) can be applied here.

 

Thanks and rgds, Jose.

 

  • 0
    TI__Guru* 93105 points

    Hello Jose,

    Most op amps, including the TLV2372, haven't been characterized with the power supplies sequenced. The expectation when using dual supplies is they will rise and fall at about the same time. If they isn't the case, then there may be the possibility of a latch condition developing where noticably high current may flow through the op amp pins such as the inputs. Even though an op amp may be checked under a particular supply sequence and not exhibit the condition process variations across time might lead to a different outcome with regard to power supply latching. Therefore, it can be difficult to provide an assurance that a particular op amp won't latch during some power supply sequencing condition.

    Many op amps will tolerate one supply coming up, or going down, at a different time than the other without any negative effects. They just don't operate in a linear manner when the other supply isn't present. However, if they do latch they can draw excessively current that could lead to damage if the power isn't removed from the remaining supply. 

    One circuit technique that we have applied successfully is to add a transient voltage suppressor (TVS) diodes, zener diodes, or even small rectifier diodes to each of the power supply lines as shown in the figure below as Zs1 and Zs2. If one power supply line is connected, or disconnected, before the other Zs1, or Zs2, becomes forward biased and provides a path for the current coming from the other supply. In the places where we have applied this technique we have not observed any instances where the op amp latches.

    Regards, Thomas

    PA - Linear Applications Engineering