This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS55330 holding power

Other Parts Discussed in Thread: TPS55330

Hello,

I have problem with design DC2DC circuit around the TPS55330.

I summarized the problem at the attached PDF file but in title-

I design DC2DC PCB that can select the output voltage between 3 levels by select feedback resistor.

I tested the PCB under load (2A) and the output voltage holds perfect.

I add the design to my main PCB (same design) and that time the voltage was OK without load and with load the voltage on "FB" stars to change around 1.229V and because of that the output voltage was not stable.

Can someone help me to put the finger on the PCB area that can cause "FB" voltage not stable?

Thanks

Yuval

 

TPS55330 Transmitter power supply.pdf
  • Hello everyone,

    I found the problem at my circuit.

    The problem was cross talk between the switching frequency at SW and the feedback resistor FB.  When the current increases spike lass the 0.9 volts accrues and the DC2DC stop function well.

    I add capacitor of 1uF in parallel to the feedback resistor and the DC2DC start to work even under load.

    I correct the PCB layout and the problems of cross talk vanish.

    Be careful with the layout of the DC2DC

    Yuval