I am using LTM8503 for 5V out and 2A load. i have selected Rfb=60.4K and Rt=40.2K. So i am getting 5v.
I want to increase the voltage to 5.3V and i tried by changing Rt to 55.7K.but it is not tuned to 5.3V.
Please help us to resolve this.
Naidu said:and i tried by changing Rt to 55.7K
maybe this is a misspelling.But Rt adjusts the frequency, not output voltage.To adjust voltage you have to adjust Rfb.
You have not provided input voltage so I assume it is high enough to make the converter operate well as a buck. Also make sure about the power capability of your source.
Other possible reason…
It got resolved.As we were changing a different resistor instead Rfb on the board.Now we have changed the exact resistor and it is giving correct results.
You are correct that is Rfb not Rt.
can anyone help me why is it not the output is not adjusting according to Rfb
Can you provide what is input voltage? I was thinking that your input voltage may be very close to VOUT. I am assuming that you are seeing issue only when increasing output current to 2A but not at low output current.
By probing VOUT using oscilloscope, you can also find information about the stability of the power supply. Please check what the waveform looks like.
Also make sure that your input source has enough power (voltage and current margin).
Even at no load also same problem.
Other possible reason would be some downstream component either clamping VOUT or current limiting the part. You can try to isolate the LTM8053 from what's connected to it in the output to check this. Again troubleshooting using oscilloscope will help a lot.