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TPS54332: Voltage is dropping from 5V to 4.5V at 1A load.

V D
Prodigy 10 points
Part Number: TPS54332


Hi, I am using TPS54332DDAR IC.

I have checked Line regulation of the IC from 19.2V DC to 28V DC. With 100mA load I am getting propper 5V.

Once I increase the load the voltage is dropping. Below are the test result. What could be the reson for voltage drop? The inductor has the rating of 6A.

 image.png

I have added Schematics and layout for referance. PCB is 4 layer and inner 2 layer are PGND.

image.png

image.png

  • 0
    TI__Intellectual 1300 points

    Hi

    I hope the output voltage reading are captured using a Digital Multimeter (DMM). Some electronic load displays are quite snappy and show such behavior when loaded. We have observed this on multiple occasions 

    • EN pin is directly connected to VIN pin. That's not correct. Use a voltage divider for EN Pin connection and make sure the voltage on this pin is ~4V
    • Make sure R9 and R10 are 1% tolerance resistors. TI recommends using max 1% tolerance resistors on the FB path and COMP pin. R9 can be reduced a little bit to ~1.8k
    • Try tweaking R11 and C34. Firstly, increase R11 to around 120k
    • Use a ceramic capacitor on C24 and C25 rated for 25V. Electrolytic capacitors have higher ESR compared to ceramic capacitors. Use a X7R part if possible. 
    • Layout looks okay.

    Regards

    Nikhil