Poor load regulation Designed with EF20 core+DPA425
Hi,
I have implemented my design on the EP68 PCB board with only 5V output. Tested at the input of 30VDC and 50mA load, O/P is 4.63VDC and at no load condition O/P is 5.33VDC.
Attached DOCs: Schmetic+PIxls design sheet+ Actual transformer construction+Drain Voltage Waveforms.
Plz suggest how do I improve my load regulation???
回應
I have tested the Voltage across C, following are the results
Input Across C7 Load
30VDC 9.5VDC 50mA
30VDC 6.25VDC No Load
I think the Bias Voltage is Less as u said. Now how do I increase the Bias Voltage?
pritam
PLS modify R3 from 100ohm to 2ohm, and check the regulation. If the no load output can be around 4.6V, then you have to modify the feed back resistor.
Regards
No load o/p was around 4.6V so changed the feedback resistors. now getting O/P of 5.11 V, 15V and -17V @ loads of 240mA, 40mA and 50mA. resp. Attached O/P waveforms. Plz give suggestions to optmize
THANKS.
I guess you do not like the regulation. But it is really hard to solve it since only the 5V channel is close loop and the other two outputs are open loop.
Two possible solutions to improve your problem: 1. dummy load for the other outputs, this is the easiest way but efficiency willl suffer . 2. Optimize the transformer. but you have to try different transformer.
regards
Pls check the voltage across C7, and make sure the voltage is high enough. And you can use an 10V external power supply to power the optocoupler, and I believe the regulation of the 5V shoyuld be good with the external bias.
regards