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LMV431A: What is the cathode current in a comparator configuration when the output is at a high logic level?

Istvan Adam
Prodigy 90 points
Part Number: LMV431A
Other Parts Discussed in Thread: LMV431, TLV803E, TLV431, TLVH431, TL431, LM25037, TL331B

Tool/software:

Hi!

I would like to use an LMV431 as a comparator. My question is: When REF < 1.24V (i.e., when the output is at a high logic level), how much current flows through the cathode?
I have created a quick example circuit to illustrate my question.

If no current flows through the cathode, then half of the supply voltage can be measured across R4.
However, some current does flow through the cathode, which changes the voltage drop across R4.

If I understand the datasheet correctly, this might be the "Minimum cathode current for regulation," which is typically 55 µA.
Please help me clarify this question.

  • +1
    TI__Expert 3920 points

    Hi Istvan,

    Thanks for your question!

    First, my recommendation would be to consider using a voltage supervisor for this type of application. One example of a simple voltage supervisor that can accomplish this type of functionality could be the TLV803E.

    https://www.ti.com/product/TLV803E

    Additionally, we unfortunately do not have this leakage current information for the LMV431. However, this graph does exist for the TLVH431 and the TLV431 shunt reference which also have a 1.24V internal reference.

    I hope this helps!

    Best Regards,

    Andrew Li

  • 0 in reply to Andrew Li
    Prodigy 90 points

    Thank you for the reply! In the meantime, I decided against using the TL431 solution, as there is no specific information about the cathode current. I'm designing an OVLO circuit with hysteresis for an LM25037. I'm extending the LM25037's UVLO circuit with an OVLO circuit that controls the LM25037's UVLO pin.
    For this task, I chose a TL331B, though unfortunately, it requires an external reference.

  • 0 in reply to Istvan Adam
    TI__Expert 3920 points

    Hi Istvan,

    Thanks for the update!

    If you don't have anymore questions, I will close this thread. To reopen this thread, simply reply to this message!

    Best Regards,

    Andrew Li