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TPS40056: TPS40056 damaged

Jeong jongkun
Prodigy 30 points
Part Number: TPS40056

Hi.

Designed with TPS40056 and being tested.

The design specifications are as follows.

- Input Voltage Range: 20V~36V

- Output Voltage Range: 0.2 ~ 30V

- Tracking Voltage Range: 0.2 ~ 2.5V

There was a problem when I used the SS / SD pin for ON / OFF control.

Tracking voltage was varied from 0.2V to 2.5V and output was up to 30V.

At this time, if the SS / SD pin is turned on/off at 2.5V using TR, the TPS40056 will be damaged.

I do not know the cause of the problem yet and I need help.

The design refers to "PMP5583".

Please answer me.

  • 0
    TI__Mastermind 32200 points
    I am assuming that when you set Vout to 30V, that vin was up at 36V or so? Can you share a schematic with me please? Thank you.
  • 0 in reply to David Baba
    Prodigy 30 points

    The input voltage is 36V and the output voltage is 30V.
    In the test, the output voltage no problem up to 12V, but TPS40056 only occurs when the output voltage is 15 ~ 30V.(@no load)
    Note that there is no problem when the input voltage is turned on / off, but the problem only occurs when operating with enable (ss / sd).
    Schematic attached.
    Thank you.8304.SCHEMATIC.pdf

  • 0 in reply to Jeong jongkun
    TI__Prodigy 225 points

    Can you please explain the statement "the controller is damaged"? Is it not working anymore? Is there a short from Pin 12/SW to GND?

  • 0 in reply to Jeong jongkun
    TI__Mastermind 32200 points

    Hello,

     

    Thanks for sharing your schematic.  As Matthias mentioned, can you detail what has damaged on the IC.

    Grab a DVM on diode setting and measure between Vsw and Gnd.  It should read ~0.7V with Red cable on Switch Black on Gnd.  And OL the other way around.  Also please can you check the Gate to Source of Both FETs.  It should not read short in either direction.

    I have reviewed and the one thing that concerns me is R45.  This could potentially cause cross conduction due to dv/dt snap on of the low side FET when the high side is switching on.  Please change R45 from 4.7R to 0R.

    One last thing I am curious to know, is this...

     

    Is you SS/SD being pulled fully to Gnd on a restart?  Is SS being engaged correctly on a restart?  i.e. is SS working on a Restart?

     

    Thanks.

  • 0 in reply to MatthiasUlmann
    Prodigy 30 points

    Thank  for your reply.

    "Sw", "Ilim", "Boost" Pin seems to be shorted.
    This is the same in repeated tests.

    1. It was confirmed that the voltage exceeded the Vin voltage during the transient test of the "SW" pin.

    2. Changing R45 to 0OHM does not improve the problem.

    3. SS / SD seems to be working normally when restarting, but we will check again.
        It is necessary to check whether repeated tests are causing problems.

    Thank you.