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OPA197-Q1: Maximum Allowable output sink current during unpowered State

Manoj Turpati
Intellectual 310 points
Part Number: OPA197-Q1
Other Parts Discussed in Thread: OPA197

Tool/software:

Hello TI,

I have a query regarding OPA197-Q1 output pin sink current during unpowered condition of the device. I could not find this information from the datasheet, however from the figure 7-12 in the datasheet, i undertsand that there are clamping diodes available on the output for ESD protection. But in my application i might encounter some transient current of 40mA for 100us flowing into the output pin when the device is unpowered. Could you please let me know if this condition is acceptable for the device or the maximum allowable current that the output pin can sink/withstand for 100us without causing permanent damage to the device when it is not powered.

Best Regards,

Manoj.

  • 0
    Guru 318700 points

    The datasheet does not specify a limit, so it might be zero. But you could assume that it's the same as the input pin limit, i.e., 10 mA. In any case, 40 mA is too much.

    Also note that the current flows into the power supply, i.e., it will charge the decoupling capacitor(s) and (partially) power up any devices connected to it.

  • 0 in reply to Clemens Ladisch
    Intellectual 310 points

    Hello Clemens,

    Thanks for the response. But i found a different answer in the below thread.

    OPA197: Output lightning protection test with product unpowered - Amplifiers forum - Amplifiers - TI E2E support forums

    Does it applies to OPA197-Q1 as well ?

    Thanks,

    Manoj.

  • 0 in reply to Manoj Turpati
    Guru 318700 points

    I do not see any contradictions. What specifically are you asking about?

  • 0 in reply to Clemens Ladisch
    Intellectual 310 points

    Hello Clemens,

    I wan to know whether internal ESD clamping diodes on the output pin of OPA197-Q1 can withstand a forward current of 40mA for 100us when the device is not powered. 

    The E2E thread that i have mentioned in my previous response had an answer suggested for the same. I just want to know whether it applies to OPA197-Q1 or not. Here is the snapshot of the response from the thread.

    Here Mr.Thomas Kuel said that he tested the similar(10mA continuous current) ESD diodes of precision amplifiers for 100mA forward current and they didnt fail. So kindly let me know whether the ESD diodes can withstand 40mA of foward current for 100us when OPA197-Q1 is not powered. I hope i am clear with my question. let me know if you need further clarification.

    Best Regards,

    Manoj.

  • 0 in reply to Manoj Turpati
    Guru 318700 points

    ESD events are extremely short and cannot be compared to longer pulses.

    Just because some other opamp happened to survive 100 mA with no immediately apparent damage does not mean that the OPA197-Q1 will also survive, or that it would not get degraded. Thomas Kuehl wrote that "TI cannot make any assurances about what might happen." You can try to do this, but then you're on your own.

  • 0 in reply to Manoj Turpati
    TI__Guru* 77541 points

    Hi Manoj,

    Please take Clemens suggestion and make the transient event measurements for the survivability test. TI only guarantees the test results listed in the datasheet. 

    Below is the differences of OPA197 and OPA197-Q1 ESD rating comparisons.  I think that the automotive grade has slightly harsher ESD tests than industrial standard.  You have to compare the ESD pulse transient curves and calculate the amount of energy in each regulation/classification. 

    Regarding Maximum Allowable output sink current during unpowered State, you have to perform the test. Unless your test classification is a standard, there is no similarity data out there for the comparisons. So you have to perform the test. Each tests have its own specific transient waveforms. As Clemens points out that ESD ratings above are short-duration test (up to 200nsec duration) Your test is a long-duration test up to 100usec (vs. ESD strikes). It is difficult  to make the correlation about the device's robustness ((apple to apple comparisons). 

    If you have other questions, please let us know. 

    Best,

    Raymond