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OPA197: Is it no problem to short OPA197 output to GND(V-)?

Part Number: OPA197

 Hello guys,

 One of my customers is considering using OPA197 for their new products. They will use OPA197 as a voltage follower.

 They have a questions about the device.

 Could you please give me your reply?

 Q. Is it no problem to short OPA197 output to GND(V-)?

      In other word, is the device broken when the output is short to GND(V-) and after removing the short condition,

      is the device electric characteristics not changed?

 Your reply would be much appreciated.

 Best regards,

 Kazuya. 

  • Hi  Kazuya-san,

     Q. Is it no problem to short OPA197 output to GND(V-)?

    Enclosed are OPA197's short circuit protection specification. If a design is following a recommended specification, the OPA197 should not get damaged from the op amp's short circuit conditions. Yes, the part will heat up as shown Figure 37, but it will survive the fault condition, say by accident or for a short period of time (only subject to one op amp per package). However, it does not mean that the part will survive the short condition indefinitely at any temperature, especially at an elevated temperature. In addition, sourcing and sinking have two different characteristic relationships, which a designer needs to take into account the ambient operating conditions (worst case) and derate the short circuit current accordingly. 

    Best,

    Raymond

  • Nakai-san,

    The OPA197 short circuit condition is specified as "Output short circuit (note 2) - Short-circuit to ground, one amplifier per package." Therefore, that is the output short circuit condition that TI assures the OPA197 output can tolerate.

    When I have asked the OPA197 design team about an output short circuit to V- or V+ they have told me it should survive a momentary short. The concern with any short circuit condition is the output stage power dissipation during the short, making sure the transistor junction temperature (Tj) doesn't exceed the 150 degC maximum. The risk when shorting the output to a supply rail is the power dissipation can be much higher than when it is shorted to ground. That is because instead of there being for example 15 V across an output transistor while supplying the high short circuit current, now there is 30 V across the transistor when the output is shorted to -15 V.

    In general, it is best to avoid conditions such as shorting the output to ground or a supply rail because it unnecessarily causes the Tj to surge. Doing this repeatedly could have long term reliability implications; just as operating an op amp under Tj maximum conditions could.

    Regards, Thomas

    Precision Amplifiers Applications Engineering