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UCC28C43-EP: Chip burns out after freezing

Eugene Tikhonov
Prodigy 65 points
Part Number: UCC28C43-EP
Other Parts Discussed in Thread: UCC28C43, UC1843A

Hi Team,

I have an issue with UCC28C43-EP. It burns out in our design after low temperature test( -40 celsium). I'm trying to find out why.

I've attached the part of the schematic and PCB layout. Could you look at that? May be there is some mistake in the IC connection.

We keep our device in the frozen camera during 2 hours at -40 С, then turn the device on. As a result UCC28C43-EP has a short circuit between VDD and GND.

Note. The Device is the Brake Supply Board. Device supplys the electromagnetic brake in the electromechanical actuator.

3113.SCH.pdf

  • 0
    TI__Genius 13660 points

    Hi Eugene,

    I want to check if the device is damaged after the short circuit at -40C. Could you test the device again at normal temperature after -40C testing? 

    Regards,

    Teng

  • 0 in reply to Teng Feng
    Prodigy 65 points

    We did. Device is still damaged after short circuit in UCC28C43-EP. After replacing UCC28C43-EP device is in good condition again.

    We repeated it 4 times.

    The procedure is as follows:
    - we freeze our device in the cold chamber for 2 hours with no power;
    - then we turn it on in the cold chamber ;
    - UCC28C43-EP burns out immediately after power the device on;

    We have 6 pcs. of  UCC28C43-EP in our device. After each test 2 of them burn out (different instances every time)

  • 0 in reply to Eugene Tikhonov
    Prodigy 65 points

    I did several tests with UCC28C43-EP in our device in the  cold chamber

    I have next results:

    - the chip burns immiatelly after start PWM command

    - waveforms of VDD and OUT are attached

    Doc2.pdf

  • 0 in reply to Eugene Tikhonov
    TI__Genius 13660 points

    Hi Eugene,

    As you said, it can work at normal temperature. But I don't understand the schematic can work, because I think there is no inductance for limiting current when the MOSFET is turned on, which will damage MOSFET, maybe I am not familiar with this application, Could you help explain it for me?

    1/. how does this schematic work? 

    2./ In this application,  Ifb1>2.5V will terminate PWM output, if Ifb1 <2.5V, PWM works on maximum duty cycle?

    3./ where is 15V_B1 come from?  Since after device turn on at 8.4V, the changing current at VDD pin is 12.9 mA, it is enough to supply VDD, the waveform shouldn't charge and discharge for many periods.

    4/. what value is C11?

    5/. 1MK is 1uF?

    I'd like to check that if there is any other devices damaged besides  UCC28C43?  

    Regards,

    Teng

  • 0 in reply to Teng Feng
    Prodigy 65 points

    Hi Teng,

    we solved problem by replacing IC from UCC28C43-EP to UC1843A-EP (bipolar version). UC1843A has a higher max voltage 30V and internal protection Zener diode. it looks like we have voltage spikes because our PCB layout is not perfect.

    Also we changed capacitors Ccopm (C10) and Cvref (C14): 0.01uF instead of 100  pF.

    Problem solved.