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TPS54561: TPS54561 the Inquiry about using parts

Kang Mingoo
Prodigy 20 points
Part Number: TPS54561

With the circuit of TPS54561 as below A problem occurred during use

[Problem]

- SW(No.9 pin) <-> gnd short

- If you remove the tps54561 during repair, The circuit of the input/output is normal.

input/Output specifications are as follows:

1. input: SMPS 48V@20A

2. Output(Load): 12V@3~4A

Q-1. Are there any examples that would cause the same problem as now?

Q-2. Are there any conditions that exhibit the same symptoms as the problem?

  • 0
    TI__Genius 13735 points

    hi, Kang,

    Not very clear what's you problem is, the SW to GND short is happened at what kind of input or during any test. The output is 12V 4A, on SCH is 15V to 24V. How is input current reach to 20A ? Any other loading in parallel.

    Elena

  • 0 in reply to Elena Gao
    Prodigy 20 points

    I made a pcb with the circuit as shown in the picture.

    There is no overcurrent and no noise at the load stage, but the above problem occurred.

    Ignoring the sch name, the actual output is 12V.

    Is there anything that could cause the same problem as now?

  • 0 in reply to Kang Mingoo
    TI__Genius 13735 points

    hi, Kang,

    What's your loading condition ,could you try to use a constant current like 3A to chekc if the board works. add ne 0.1uf in input, any you could also share you layout for double check.

    Elena

  • 0 in reply to Elena Gao
    Prodigy 20 points

    The user turns ON/OFF the EN signal in the FPGA.

    To check the operation of the board, the TPS54561 chip was removed.

    Adding the 0.1UF cap has nothing to do with what I asked

    * share the layout,
    * Please let me know the expected problem that the SW pin inside the chip could be shorted to GND.

       - ex) The characteristics of the chip being manufactured may be poor, etc.

  • 0 in reply to Kang Mingoo
    TI__Genius 13735 points

    If the input side have high frequency noisy then 0.1UF could help , 

    EN voltage should within spec <8.4V. 

    SW to GND internal is low side MOS, so consider if the voltage overstress here. 

    Is the thermal pad connect to GND. 

    any ABA test tries on this board. 

    could you provide the top mark picture or lot number if you suppose this is a quality issue.

    Elena

  • 0 in reply to Elena Gao
    TI__Genius 13735 points

    And you mentioned as

    "- If you remove the tps54561 during repair, The circuit of the input/output is normal. "

    Not understand how it generate output voltage without this IC. 

  • 0 in reply to Elena Gao
    Prodigy 20 points

    Sorry, The meaning seems to have been misinterpreted

    "After removing this chip, when checking the input and output, it is normal without short circuit."

  • 0 in reply to Kang Mingoo
    Prodigy 20 points

    There is no high-frequency noise on the input side and almost no ripple.

    EN voltage is 3.3V
    Thermal pad gnd connected

    I don't think it's a quality problem.
    We wanted to ask what could be the cause of the problem.

  • 0 in reply to Kang Mingoo
    TI__Genius 13735 points

    Only looking from your circuit there is not conclusion of how could the short happen, and no waveform show the performance before the pin short happen. 

    Usually short happens @ EOS, like over voltage . I didn't see any additional information here.

    Elena