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TPS62175: TPS62175 question about FMEA test.

Bob Lee62837
Mastermind 7230 points
Part Number: TPS62175

Dear support member,
My customer used TPS62175.

I have a question about FMEA test.

Q1.
When the pins 1, 4, 6 are opened,
what happen the state of the IC when each pin is connected to VIN?

Q2.
When the pins 1, 4, 6 are opened,
what happens to the condition when IC is mounted reverse?


Best regard.
Bob Lee.

  • 0
    TI__Guru*** 142750 points
    Hi Bob,

    I don't quite understand your question. For Q1, do you mean to disconnect PGND, AGND, and NC from GND and connect them to Vin one pin at a time (with the other 2 pins still connected to GND)?

    Can you rephrase Q2 as well?
  • 0 in reply to Chris Glaser
    Mastermind 7230 points

    Dear Chris Glaser,

    Thank you very much for reply.
    Q1 is solved by my customer.

    Q2 is rephrased.

    Q2 rephrased
    When the pins 1, 4, 6 are opened,
    what happens to the condition when IC is mounted by rotating it 180 degrees?


    Best regard.
    Bob Lee.

  • 0 in reply to Bob Lee62837
    TI__Guru*** 142750 points
    Hi Bob,

    Thank you for answering Q1.

    I don't understand Q2. Can you try to explain it step by step? For example:

    1. Normal schematic/PCB design.
    2. Open (disconnect the IC pin from the PCB) pins 1, 4, and 6
    3. Rotate the IC 180 degrees. Are pins 1, 4 and 6 still open? Or is it the opposite pins?

    Alternatively, you can send me the schematic condition that you would like feedback on.

    Is this required for an FMEA analysis or some debugging of a specific circuit?
  • 0 in reply to Chris Glaser
    Mastermind 7230 points

    Dear Chris Glaser,

    I'm sorry.
    I misstaked.

    I explain it step by step.

    1. Normal schematic/PCB design.
    2. Rotate the IC 180 degrees.
    3. It mounted the pins.

    Could you teach about the confirmation of operation when mounted rotating 180 degrees?


    My customer need FMEA analysis.

    Best regard.
    Bob Lee.

  • 0 in reply to Bob Lee62837
    TI__Guru*** 142750 points
    Hi Bob,

    Thanks you for explaining.

    If the IC is placed 180 degrees reversed, some pins will not be connected properly.

    Specifically, the PG pin on the IC will short the VIN net on the PCB. Assuming Vin is above 7V, this will likely damage the PG pin.

    As well, the SLEEP pin on the IC will short the EN pin on the PCB. If EN is connected to Vin, this will also damage the SLEEP pin.
  • 0 in reply to Chris Glaser
    Mastermind 7230 points

    Dear Chris Glaser,

    Thank you very much for reply.

    I reply my customer your answer.

    I will feedback it.

    Bob Lee.
    Best regard.

  • 0 in reply to Bob Lee62837
    Mastermind 7230 points

    Dear Chris Glaser,

    I replyed my customer your answer.
    I have a add question.


    In this state（when mounted rotating 180 degrees)

    Q1.
    Does IC output the output voltage?

    Q2
    Does IC ignite fumes?


    Best regard.
    Bob Lee.

  • 0 in reply to Bob Lee62837
    TI__Guru*** 142750 points
    Hi Bob,

    Q1. Your customer should be able to answer this on their own. But perhaps I still do not understand how they are considering the IC to be positioned. When the IC is placed 180 degrees rotated, the inductor (which is the IC's main output pin) will be connected to the NC (not connected) pin. So, there is nothing driving the inductor, which would then not drive the output voltage.
    As well, the VOS pin (which is the output voltage) would be connected to the IC's FB pin. FB is an input, so it cannot drive VOS.

    Q2. We do not define how an IC or pin will fail. As I said before, the PG and SLEEP pins will likely see voltages that greatly exceed their ratings. The customer needs to double check how these pins are connected in their system and how they would be connected if the IC were rotated.

    Just take their schematic and relabel the IC's pins to see the new connections in their circuit. It should be easy to understand after doing this.