UCC27524: Failure

Hello Anuradha,

Thank you for interest in the UCC27524. There are several conditions that can lead to the driver device failure, so I will ask some questions to help resolve may be the issue in your circuit.

The description of working with the no load condition and having the failure issue with load I expect that with the load condition there is higher dV/dt in the power train and higher current which can both lead to noise spikes or ripple on the driver control signals and possibly voltage spikes on the driver outputs.

Confirm that all voltages are within the datasheet recommended ratings, VDD 4.5V to 18V, IN pins 0 to 18V during operating conditions, including voltage spikes or noise.

The two initial things I would confirm by recording scope plots are:

1) Confirm INA and INB do not have high frequency ringing that may false trigger the driver outputs. Record INA, and INB with scope probes tip and ground as close to the driver pins as possible. Record on a time base that includes several cycles and also on a time base that you can see the turn on and turn off details including any voltage ringing.

2) Record OUTA,  OUTB, INA and INB to confirm if there is voltage overshoot or undershoot on the driver outputs. Excessive voltage transients on the driver output can result in failures as you describe.

To resolve possible driver input signal noise issues, we recommend a small R/C filter on the driver inputs with the capacitors as close to the driver pins as possible. Start with 51 ohms and 100pF which is only a 5ns time constant and should not affect performance very much.

If there is driver output overshoot or undershoot, we recommend placement of small Schottky diodes from the driver outputs to VDD and GND to limit the positive and negative voltages,

Confirm if this addresses your issue, or you can post additional questions on this thread.

Regards,