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TL432: Request the SCH review.

David Kim2
Genius 3305 points
Part Number: TL432
Other Parts Discussed in Thread: TLVH432

Hi

My customer used TL432 and op-amp to construct the OCP circuit.
However, there have been many defects recently.
At first, They thought it was a defective part.
But they want to check if the circuit is wrong.
Can you review the attached circuit?
The attached file contains circuit diagrams and bad waveforms.

ThanksTL432 .xlsx

  • 0
    TI__Expert 9000 points

    Hello,

    I do have one question: in the excel document that you attached, there is a "defective" and "good" waveform. Is a different TL432 being used for each waveform? Are they seeing this issue only with certain TL432 devices?

    Jackson

  • 0 in reply to Jackson Wightman
    Prodigy 40 points

    Hi thanks your answer

    The defect phenomenon does not follow the smps PBA and occurs only in some (1%) TL432.

    I wonder what is the cause of the defect.

     

  • 0 in reply to kim do yoon
    TI__Expert 9000 points

    Can I ask for clarification as to why a 1.23 V reference is being used for the TL432? The VREF on the datasheet for the TL432 is specified at 2.5 V, so 1.23 V would be abnormal. For 1.23 V a device such as the TLVH432 would make more sense.

  • 0 in reply to Jackson Wightman
    Prodigy 40 points

    Hi thanks your answer

    It was used as TLVH432.

    The defective phenomenon is the occurrence of oscillations in the anode voltage waveform.

    As for the normal waveform, a 1.24V oscillation-free waveform is measured.

    best

  • 0 in reply to kim do yoon
    TI__Expert 9000 points

    Got it. Right now, I am not seeing any major issues with your circuit, but before concluding that, I have a few more questions.

    What is the purpose of the pnp circuit configuration that connects to the input of the TLVH432? Is it simply to provide 5 V to the input of the TLVH432 once 24 V is turned on?

    And just so I understand correctly: This is only happening in specific TLVH432 devices, right? You said 99% of the devices you are using have no issues, correct?

    Another thing to check is that the TLVH432 is receiving its minimum current seen in the datasheet: