TOP270 function questions
Good day. We try to using your device of TOP270 and TOP266. We find the device would shutdown himself. The operating time is around 84seconds, and 49seconds idle time, if i put a 10K ohm resister on X pin. Is it correct work ?
84/(84+49)=63% is it the "I-LIMIT" percentage that you said?
Comments
Hi Kenobi. please refer the attachment. input is stable 110V ac source. Device U9 is a OC/OV feedback IC. Anyway. Everythings are OK when we sink 2.2A DC out @t=0seconds. Good feedback/conttol waveform. But after some time(~44seconds, if Xpin short to GND). TOP270 shutdown himself, and going to a weirdness work/shut cycles. operate power is around 35W/in and 27W/out. Heat is not the problem, we prove it already. could you please tell us whats wrong.
Do you have a clamp connected across the primary winding of the transformer? What is the peak drain voltage across the drain-source during off-state?
Do you have OVP enabled? What is the peak voltage across C58?
1. Yes. We connected transformer Pin 2 and 3.
2. The peak voltage of drain is around 250V. it sure be during OP voltage.
3. OVP? Are you mean R54 loop? We remove the resister for debug.
4. The peak voltage of C58 is around 45V maximal, and break down voltage of coupler C-E is 70V minimal.
please refer the attachment. there are some measurement waveform. So, if there is not coupler or OVP/OCP problem, anything eles?
Todd
Sir,
1. Can you check if the optocoupler is overheating? 45V across C58 is high for the bias winding.
2. Could you send me a complete schematic and transformer design file please?
Sir,
Can I have more information about your design please? The maximum duty cycle for the TOPSwitch-JX device is 78%, therefore, in your case, the duty cycle limit is not hit. Connecting a 10k resistor on the X-pin causes the current limit to be at 75% of the nominal value and as you continue loading the device, this limit maybe hit, causing the device to shutdown/auto-restart.