I am trying to replicate the mEZD41503AB Development board according to my PCB size, here I used all the recommended part and circuit diagram from monolithic power system. This circuit exactly same as development board, here I used only USB C connector for power port. I wanted to get 5V to 12V. When I give the input voltage, I got the exact same value at the output side. I tried to check the output by changing the feedback resistor. When I check the output voltage, it is around 4.6V. Can you give some suggestion how I get the required 12V output?
Looks like the resistors on the FB pin are set for 5V out. So it is almost working. Have you measured Vin? USB-C is complicated, but I fear the part you have chosen can draw too much power for the USB to provide. I may well be wrong I think you can count on 5V 3A on the input side but there is the possibility to negotiate with the host side digitally to get 20V 5A and maybe in between just 12V by itself.
Thank you very much for replying me! Please let me know your recommended R1 and R2 values to get the 12V out.
Well I am just some dude on the internet, but to keep the math simple the FB regulation point is 1V So I would use a 100k resistor for R2 and then that gives 1100k or 1.1Meg for R1.
I would try it first with a stiff ( high current capable) 5V supply see if it works before progressing to USB-C power.