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UCC27211: Driver Issue

Alfred Logico
Expert 5060 points
Part Number: UCC27211

Tool/software:

Hi Team,

My customer is using our UCC27211 in their design. Below is the waveform captured for the drive signal to the input side of the driver IC and Vgs on mosfet, as we can see below waveform, Ch4: Vgs on MOSFET will suddenly become abnormal after a few cycle of normal operation.

Seeking your help to see what reason could result this problem, thank you!

Ch3: Gate drive signal
Ch4: Vgs on MOSFET

Below is the schematic of customer:

Please refer to below captured waveform, Ch3 is the Drive signal input to LI (pin 6) of the drive IC and Ch4 is Vgs on MOSFET (driven from LO, pin 8), the abnormal behavior was only occurring during steady state, on the waveform we found the gate drive output of the drive IC suddenly abnormal: The input signal pulled down but its output side (Vgs) still kept driving for around 580ns, then suddenly drops to 7V and rising to 10V within 2.6us, after this event the gate drive never outputs voltage according to input signal.

Ch3: Drive signal input (LI, drive IC pin 6)
Ch4: Gate drive voltage of the MOSFET (Vgs) (drive voltage sent from LO, drive IC pin 8)

Thanks! 

BR,

Alfred

  • 0
    TI__Genius 9770 points

    Hello Alfred,

    After power down and power up again does the device operate normally again until failure? That is, does this issue repeat with the same part every time it is powered off and on again.

    Can the customer try removing the 10uf capacitor C411 or replace it with another 100nf cap? 10uf is a large capacitance for the bootstrap supply on HB-HS and may cause issues.

    Can the customer also capture VDD on the scope or increase the input filtering? There appears to be more noise on the input signal at the time of failure.

    Thanks,

    Walter