data/text/DLP3/898379

TPS55330: TPS55330 work abnormal, does not match the formula

Part Number: TPS55330 Hi I got a problem Calculate according to the formula Input 12V, require output 16V, circuit as picture But the output is 19V, no matter if R175 is 120K or 100K Where is the problem? Thank you 1.229V x (R175/R177 +1)

Hi Jeff, Can you share the layout? Have you tried applying a load at output? Will the output voltage sitill be 19V?

In fact, I made a mistake. My original design is wrong. So change to external parts for experiment. Layout as picture. Thanks

Hi Jeff, I didn't find the detailed datasheet for inductor MSPI0530-1R0M, please make sure the inductor has enough saturation current spec. The shared layout picture doesn't show me the position of output capacitors. Please make a note on above picture. Below is the recommended layout in datasheet. The output capacitors are suggested to put close to cathode of Schottky diode and IC PGND pins so that the PCB parasitic inductance is the minimum. Meanwhile, the power traces should be wide enough. Lastly, check the FB pin voltage to AGND with a DMM. It should be 1.244V.