LNK30X output voltage too low, BP and FB pin voltage too low
Hello,
I am having a problem with AC/DC converted based on LNK304. I want to have 3,3V output voltage from 100-230VAC.
I configured feedpack so that both resistors by FB pin are 1k. I use ES1JL as a rectifing diode (and diode for FB network), 1mH inductor and 60uF output capacitor. I load the converter with 100Ohm+green led (~10mA)
My problem is that:
1. I do not get 3.3V at the output - rather 3,14V
2. The voltage at FB pin is not 1.65V (in reference to the ground). It is approx. 0.8V
3. The voltage at BP pin is 5,14V rather than 5,8V
I attach the schematic for the design.
What can be wrong in the design
Comments
What's the output voltage at No Load? What's your full load? The FB voltage and BP pin should be measured with respect to source pin , could you remeasure the FB pin an BP pin voltage with respect to source pin and send us the data?
I will check these voltages in reference to S pin.
My maximum load is 70mA (peak), average is 40mA. The voltage with no load is 3,20 with respect to GND.
Ok, Please verify it and let us know.
What's the output voltage at No Load? What's your full load? The FB voltage and BP pin should be measured with respect to source pin , could you remeasure the FB pin an BP pin voltage with respect to source pin and send us the data?