200W SMPS with TOP261Y is oscillating!
Hi, this is the first prototype of this project.
The power supply was found to be oscillating. The CONTROL voltage, Vc turns on/off at the 4.8V to 5.8V window.
I've attached the CRO diagrams as below.
Comments
my circuit waveform of VDRAN is not like with data sheet . Please Help Me
Opps sorry, I forgot to attach the CRO diagrams. I've reattached as below.
I believe it has something to do with the feedback loop. So I've tried:
a) reducing R8 to 5R so to increase the current to the C-pin
b) reducing R8//R10 so to increase the LED current on the opto-coupler
c) adding soft-start circuit as suggested in the AN43 app notes
All led the same result - Still oscillating. It's very frustrating, please help.
Many thanks.
The schematic diagram attached was probably too small. I've reattach as a file below.
Someone please help.
I was dreaming to use the TOPSwitch controller after attending the seminar, and tried so hard to convince my boss to use it in our new project. It has got to work!
my circuit waveform of VDRAN is not like with data sheet . Please Help Me