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TPS54201: Tps54201 died when connected in parralel

Maciej Marguz
Prodigy 70 points
Part Number: TPS54201
Other Parts Discussed in Thread: LMR16006

Hello,

I have build a circuit of 4 channel led driver using 4 tps54201 parts. The board is very small 1.5cmx3cm. i have packed all parts same way and close each other. The inductors are unshielded. The current is set to 200mA. On the bottom side i have small uC located for dimming control. All parts are supplied from the same source, 15V. 

Always, one of the tps54201 is dieying after a few seconds. There is no shortcircuit on the board. Is there any chance that one TPS interfere to others?

  • 0
    TI__Genius 13001 points

    Hi,

    Does the these four devices share the same inductor or any other components? Could you share the schematic for further analysis?

    BTW, TPS54201 is used for what application? Appreciate for your any input.

    BR,

    Robin

  • 0 in reply to Yuting Shao
    Prodigy 70 points

    Hi Yuting,

    forgot to add board and schematic, here are:

    board - top:

    bottom:

    On the bottom side, there is buck converter to 3.3V (power for uC - for diming control with soft PWM)

    On top 4 TPS54201.

    All of them are share same input capacitor only. It is used to provide 4 separate channels for constant current (200mA - Rshunt - 0R5).

    uC just send the PWM (with different duty to each TPS separately)

    Schematic is based on documentation, 4 channels are identical:

    Inductor (unshielded) has a following parameters:

    Rated Current 1.1A
    Inductance 6.8uH
    DC Resistance (DCR) 210mΩ

    Single capacitor is on the supply input - 10uF/16V. Capacitors 100nF and 82nF are rated to 100V. Led capacitor is 10uF/6V3.

    TPS54201 has died on open circuit, without connected LED. I have doble checked the board for any short-circuit but negative result.

    When it dies, it has short-circuit between SW and GND. 

    I have replaced died chip, but that one died as well soon. In the meantime, second chip has died as well. Any advice?

    It has to power four 1W red led, which have maximum current ~400mA

    best regards

    Maciek

  • 0 in reply to Maciej Marguz
    TI__Genius 13001 points

    Hi Maciek,

    Did you apply PWM signal firstly? Or just power supply and then device died without any load?

    Robin

  • 0 in reply to Yuting Shao
    Prodigy 70 points

    Hi,

    the order of the power supply is not controlled. The 3V3 power supply is created by LMR16006, and uC is started immediatelly.

    The same time all TPS54201 are power from the same source. 

    Device has died without any load, I had no time to even catch that moment on osciloscope. 

    best regards

    Maciek

  • 0 in reply to Maciej Marguz
    TI__Genius 13001 points

    Hi Maciek,

    It looks odd because there is no mistake in schematic and layout. Can you try with EVM and see if the symptom can be reproduced?

    Robin