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UCC27282: Failed gate driver near pins 4&5 HS/HO pins

dax inman
Prodigy 10 points
Part Number: UCC27282

Tool/software:

Hi,

Recently we had 3 failures with the UCC27282DRCR gate drivers, all externally seem to have failed and burnt the driver in the same place, the corner near pins 4 and 5.

    

Schematic:

not shown; low side shunt resistor 1.5mΩ , voltage sense on HS 50k impedance

Top layer layout

Application is for a motor driver with ~50V V_batt, PWM freq 20 kHZ (center aligned).


MOSFET: BSC026N08NS5ATMA1

D12/D13 (undervoltage schottky protection): BAT46X (100V 1V@ 250ma SOD-523)

D14/D15 (overvotlage zener): BZT52C15S-7-F (Zener 15V 200mW SOD-323)

Duty cycle is limited in software to 95% max.

Both failures seem to be sporadic, working well all the time and then failure occurs. I don't have any scope shots of the failure. In one instance a high side mosfet also failed short, in another just the driver failed.

I know the bypass capacitor is undersized, but there are 10uF and 2.2uF caps close to the drives, at the output of a 48V -> 12V buck. 

  • 0
    TI__Intellectual 1115 points

    Hi Dax,

    1. Yes, the bypass capacitor does appear to be undersized. A smaller bypass capacitor ≥100nF should be placed as close to the driver as possible. This will prevent noise spikes on the voltage supply pin. Next to this, we recommend placing a capacitor which is ≥10x the value of the bootstrap capacitor. 

    2. Can you take waveform captures of HB-HS, HB-VSS, HS-VSS, VDD-VSS, HO-HS, and HO-VSS? It would be good if you could get a capture of these while the device is operating right before the failure as well as after the failure occurs. Please take these waveforms as close to the driver as possible. I do recommend tip and barrel probes if signals are referenced to VSS. Differential probes are recommended for signals referenced to HS. 

    3. Could you give more information on the status of the device when this occurs? Does this happen during startup, shutdown, or switching operation? Does this happen at a specific temperature, or is it at room temperature?

    4. Could you provide the bus voltage, and the input voltage level?

    5. Is the FET the only other component which was affected? 

    Thank you for providing this information. Let us know if you have further questions. 

    Best,

    Amy