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Original question:

WEBENCH® Tools/TPS40400: Program process difference

WEBENCH® Tools/TPS40400: NA

user6371410
Prodigy 20 points
Part Number: TPS40400

Tool/software: WEBENCH® Design Tools

TPS40400 around 1% damaged failure rate was found at manufacturing process  (function test station).  a test fixture with TI USB i2c tools, CLK  and DATA singnal pin connect to TPS40400 via test probe directly.

while the UUT is being put or remove. CLK and DATA is 3.3V at idle status. is it caused to damage the TPS40400?  should i need to control the CLK DATA with switch?

 

  • 0
    TI__Mastermind 48200 points

     

    The TPS40400 CLK and DATA pins are designed to withstand voltages up to 5.5V with respect to their own grounds and currents of a few milliamperes.  Inserting them live into a test fixture could cause damage if something is forcing them above 5.5V with respect to their ground if the 3.3V CLK or DATA has high capacitance or strong pull-up, but the typical pull-up resistors that limit current to a few milliamperes would be unlikely to damage the pin.

    What type of damage are you seeing on the units under test?

  • 0
    Prodigy 20 points

    for  damaged TPS40400,  using digital meter to measure Pin Restance against to gnd.  most of them are: Pin20 from 100K  change to 1K, Pin 13, Pin14 change to 200ohm. 

  • 0 in reply to user6371410
    TI__Mastermind 48200 points

     

    Pin 20 is VDD, the primary power input for the device.

    Pin 13 and Pin 14 are BP3 and BP6 respectively.  These are the LDOs that power most of the circuitry in the IC with BP3 providing most of the logic level and digital content while BP6 powers the gate drivers and analog regulation core.  WIth all 3 damaged, I would look for a possible spike voltage on VDD, especially if there may be cases where the load is suddenly removed as source inductance feeding VDD and the power input continues to drive current after the power stage is no longer loading it.  That can cause a very high peak voltage on the power input and thus VDD.