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TPS54360: TPS54360 PIN SW short to GND problem

user6134941
Prodigy 30 points
Part Number: TPS54360

Hi all,

  We are now using TPS54360(not TPS54360B), and found that Pin SW was short to GND when powered on about several hours.Damage ratio is about 1~2%,a big trouble. 

The schematic like this:

The maximum output current we used is 1.5A, we tested up to 3A for 1 hour after mount a new IC,not damaged,we test it in normal output current 0.5A for several days,still not damaged.

We also analysis the waveform of SW Pin and ripple of output voltage , not bad we thought.

SW PIN:

VOUT :

Ripple of VOUT:

Please kindly help me troubleshoot this issue.

Thanks and regards!

  • 0
    TI__Mastermind 27030 points

    Hi

    1. do you know it is damaged in stable statues or in Line/Load transient?

    2. what's the saturation current of inductor? is it higher than OCP point of chip?

    3. did only chip damage or any other component damage?

    4. do you have layout to share

    Thanks

  • 0 in reply to Daniel Li14
    Prodigy 30 points

    Hi Daniel Li14,thanks for your replay.

    Here are some infomation for you:

    1.The IC damaged in stable statues, the input voltage is 24V DC;

    2.The inductor is SLF7055T-220M1R7-3PF from TDK, Isat > 2A from the datasheet:

    3.Only chip damaged,when re-weld a new one,the PCBA work ok again;

    4.Top and bottom layout as below:

    the PCB is 8 layer, L2 and L7 are GND plane.

  • 0 in reply to user6134941
    TI__Mastermind 27030 points

    HI

    the damage may happen due to overvoltage or in some unexpected condition. you may need test the SW waveform with the system. see any abnormal system transient at input and output which may make the SW overshoot then damage the chip.

    another point is the input L,C which close to inpt pin , you have a 36V zener to protect the chip, but in some case, the LC may resonant which cause a overshoot voltage at Vin pin. it just my guess, so stronge recommend you check the chip with system working conditon. 

    Thanks

    Daniel Li

  • 0 in reply to Daniel Li14
    Prodigy 30 points

    OK,we'll do more tests.BTW,this PCBA has passed the 1KV Surge and 7637-5A 123V level EMC tests,so the case of damage quite confusing. Thanks any way.