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TPS62143: Output clamp inside the device

Kaji@PAN
Mastermind 7220 points
Part Number: TPS62143
Other Parts Discussed in Thread: TPS62147, TPS62148

Hi,

I would like to ask you about the output voltage clamp on the TPS62143 device.
The following excerpt from the data sheet shows that the VOS pin is clamped to 7.4V inside the device.

(question)
What kind of circuit is this clamp?
Is it a 7.4V Zener diode?
Or if the voltage rises to 7.4V, does the operation stop switching, etc.?

Best regards,

  • 0
    TI__Mastermind 23810 points

    If the FB is open, only then VOS is clamped to 7.4V. For regular operation when FB pin is connected as usual, there is no such limit on VOS pin. I do not have the information on what the internal circuitry for this mechanism is. Please let me know if you have any questions and if there is a specific reason you are looking into FB pin open behavior.

    Regards,

    Amod 

  • 0 in reply to Amod Vaze
    Mastermind 7220 points

    Thank you for your reply.
    I am currently investigating market defects.
    The device powered by the TPS62143 is destroyed.
    The device is rated at 10V, so I need to see if the TPS62143 will damage the device if it overvoltages. That's why I asked you this question.

    Once again I will ask you a question.
    What kind of circuit is the 7.4V clamp built into the TPS62143?
    Is it a Zener diode? Or is there another control circuit?
    Also, will the 7.4V clamps work if the overvoltage occurs in other situations where the FB pin is not open?

    Because of the bug investigation, I expect you to get a more specific answer than what is given in the datasheet.

    Best regards,

  • 0 in reply to Kaji@PAN
    TI__Mastermind 23810 points

    I have contacted the design team to find out more but they may not be able to find the details easily. TPS62143 is rated for only 6V max output and max rating on VOS pin is only 7V so a voltage greater than that could cause EOS failure.  

    TPS62147 or TPS62148 is a newer device that could be used as a replacement as it can deliver upto 12V max Vout so it can handle higher voltages at the VOS pin.  

    Regards,

    Amod

  • 0 in reply to Amod Vaze
    Mastermind 7220 points

    If you can't reveal internal circuit information, I will not ask you for internal circuit information.
    However, I think you can give me information on how the 7.4V clamp works.
    (Stable at a constant voltage of 7.4V, switching operation stops, etc.)
    I can't understand the answer that it causes EOS failure even though it is clamped.

    Best regards,

  • 0 in reply to Kaji@PAN
    TI__Mastermind 23810 points

    TPS62143 is a fixed output device so FB is supposed to be grounded. The feedback divider resistors are internal to the IC. So, I will need to check if the behavior for the 7.4V clamp is the same or not. I have ordered some samples to test - it will take me till middle of next week to get shipment and test. Let me know if you have any specific tests you want to run.

    Regards,
    Amod

     

  • 0 in reply to Amod Vaze
    TI__Mastermind 23810 points

    Actually, there is no way for me to test the clamp even with FB pin open as the internal feedback divider is still connected internally. The 7.4V clamp is active only when the FB pin is open for the adjustable output version parts. Otherwise, you need to follow the abs max rating on VOS pin which is 7V as mentioned in the datasheet.

    Thanks,

    Amod