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UCC21710: Output Pulse missing

JAY JOSHI
Prodigy 20 points
Part Number: UCC21710

Tool/software:

.

Hello,

I am observing strange behavior of output of ucc21710. Attached are the images and schematics.

Yellow- Gate pulse from microcontroller(25khz).

Blue - Voltage between gate and source keeping Vds=0  and mosfet is connected.

Purple- Fault pin status.(also, ready pin remains high for all the operation)

VDD= 15V, VEE=-5V.

  • 0
    TI__Expert 6730 points

    Hi Jay, 

    A couple things come to mind when looking at the waveform/schematic: 

    1. Are IN+ and IN- tied together? From the schematic it looks like both are tied to GND. I would recommend tying IN- to GND and feeding the signal directly into IN+. 

    2. From the waveform/schematic, it looks like VCC=5V, and the input logic HIGH voltage is 3.3V. This can potentially cause the issue since the maximum logic HIGH threshold is 5V*0.7=3.5V, and the input HIGH is lower than this. Suggest feeding a PWM wave of 5V amplitude to IN+ and see if the issue resolves. 

    Thanks, 

    Vivian