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Original question:

UCC27714: Can we power UCC27714 HB to HS with dedicated power supply?

UCC27714: Voltage spikes in output and input driver pulses at 300V

JEET PANCHAL
Prodigy 10 points
Part Number: UCC27714

Hello,

I am designing an inverter board for voltage above 350V. I am facing a driver related issue at 300 V DC link. 

There are voltage spikes in input and output of the driver. But at the output of microcontroller there are no such spikes. 

I am unable to remove or detect the source of the spike in my pulses.

I am attaching a picture of my driver connections. 

I would like to ask whether COM and VSS should be joined directly or should there be a inductor or resistor between those grounds. My system is a non-isolated system.

 

  • 0
    TI__Mastermind 20950 points

    Hello Jeet,

    Thank you for the interest in the UCC27714 driver. The noise spikes on the input of the driver in most cases is caused by ground bounce between the controller ground and the ground at the driver input. Noise spikes on the output of the driver typically is caused by the parasitic trace inductance of the driver output to the power switch gate, and power switch source (or emitter) back to the driver ground reference.

    Also, without careful scope probe connections it is common to see high frequency spikes on the plot that is caused by the setup. Confirm the voltage waveforms on the driver input with the probe connected as close as possible to the driver input pins and short ground connection to the driver ground. Also do the same with the driver output pins regarding scope shots. if the scope grounds are connected far away from the driver, you will likely see noise spikes due to ground bounce since there are high current pulses flowing in the driver ground traces.

    On the schematic I see capacitor on the driver input pins. I would suggest also adding resistance in series with the driver inputs to make a small input filter. This will help attenuate short duration noise spikes.

    To comment on if it is better to connect the driver VSS and COM directly or thru a resistor, it is dependent on the board layout specifically the grounds of the driver, power train and controller.

    Can you provide scope shots of the input and output with the careful probe connections? Also to comment on the layout I would need to review the board layout of the driver and power train.

    Regards,