TNY268 at 66Khz
Hello, I designed a switching mode power supply with PI expert using TNY268 and when I measure the drain voltage it appears to operate at 66 Khz (datasheet specifies 132 Khz). I´m using a zener clamp and multiple outputs (12 V with Ultra Fast diode and 5V with schottky. Which could be the problem? Could you help me?
Comments
First of all thank you for your reply. Yes, this condition is happening at low line and high line with any load condition. I´m sending you an image with the drain to source voltage at low line full load. Also I attached the circuit schematic and transformer design. Thank you very much.
According to your drain voltage waveform, TNY268 did work at 132kHz which is shown by the two center pulses. TinySwitch use on/off control with current limit operation. As you increase the load, the current limit is getting to the highest limit and the number of switching cycle being skipped is getting less, hence it will be easier for you to see the switching frequency of 132kHz.
ok, thank you very much for your help, I apreciate your time and effort. Best regards.
Could you please post your schematic and transformer design? You can use pdf.
is this condition happening at full load? Low Line?
Thnak you
PI-Worf