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TPS53319: Not able to Output Current more than 3A

user5334021
Prodigy 20 points
Part Number: TPS53319

The Schematic Diagram

When its output is below 3A, everything goes well. But when the load resistor is decreased, and it supposed to output more current. Its output turns to a sawtooth wave.

CH1 is the output voltage, CH2 is the LL voltage. At -1.4 ms, the load resistor changed.

CH1 is the output voltage, CH2 is FB voltage.

The output ripple at 1.1V,3A

  • 0
    TI__Mastermind 35165 points

    Hi ,

    The first thing I noticed in the schematic is the TRIP pin is floating. I don't think this is causing the behavior you are seeing but the maximum TRIP voltage should be 2.4V for the TPS53319. With the 10µA current source the max TRIP pin resistance should then be 240kΩ. I believe this may not be the problem because it doesn't look like the device is hiccuping. If it were related to OCP we should see the device hiccup and wait ~20ms before restarting.

    Since the device is restarting immediately, the behavior looks more like the device is getting disabled when the current goes above 3A. Two things I suspect could be causing this.

    1. Insufficient ceramic input capacitance. Try stacking more ceramic caps on top of C2 and see if that helps.
    2. Non ideal placement of the ceramic input cap in the layout. The input capacitor should be placed as close as possible to the VIN pins and the EPAD with wide traces as shown in the layout example.

    Anthony

  • 0 in reply to Anthony F
    Prodigy 20 points

    After I moved the position of C2 and add it sum to 60uF, it works well