Hi,
I posted about a month ago about a TPS65266 that wasn't outputting a voltage when supplied with an input voltage and was told to redesign my PCB.
I have done that and added a few components to make my design similar to the EVM however I am now experiencing a new problem. Buck 1 and 2 are regulating normally however Buck 3 is not. I have set it up to output 3.3V and at no load the voltage varies between 2.7V and 3.6V. When a LED is attached it regulates at ~2V.
Here is my schematic:
and PCB layout:
Please note I only need it to output 700mA and when calculated the minimum inductance was ~17uH so that's why the inductors are so big. C36 is currently a 2.4nF capacitor and I have also tried a 4.7nF capacitor. My switching waveform for Buck 3 is below:
And one further zoomed out
Any help will be greatly appreciated for double checking the loop values would be greatly appreciated.
