Can we effectively decrease Auto restart time of TOP switch?
Hi good morning,
I am working on power supply design using TOP267KG-TL.
Inputs: 19.2Vdc - 264Vdc
Output: 12V, 5W. 12V is converted again to 5V.
Question 1) When I am giving input 14Vdc then converter is going in auto restart mode. When I am making input voltage jump from 14V to 19.2V, converter is not starting at19.2Vdc immediately, because it is in autorestart mode. Can we decrease converter auto restart time very small value?
note: When I am giving input 13V converter is not in autorestart mode. When I am giving input voltage jump from 13V to 19.2V, converter is starting immediately at 19.2Vdc.
Question 2) By using control pin with R & C, How much we can decrease this autorestart time? After making this change still system will stable?
For reference, Please find attached waveforms.
Hello Mayur@111,
Good day and thank you for choosing Power Integrations.
To answer your question, yes, you can adjust the auto-restart timing of the TOPSwitch-JX by adjusting the capacitor value in the RC circuit that is connected to the control pin from the recommended 47 uF down to 10 uF. Above 47 uF may be acceptable, but further testing is required if there will be no issue during the startup of the PSU since it acts as an energy storage and provides power to the device during startup. Unfortunately, we currently don't have any reference design or study on how much auto-restart time can be reduced upon varying the capacitor value. Further testing on your side is needed to verify how much time is reduced and if the system will still be stable.
Additionally, it seems that the auto-restart time is not the cause of the issue. It is likely to be exceeding the current limit protection threshold (please see the attached image) of the TOPSwitch-JX device at startup due to very low input voltage. Once the current limit protection threshold is exceeded, the device will trigger auto-restart. It is also stated in the datasheet that the minimum drain supply voltage that the TOPSwitch-JX can operate is 18 VDC (please see the other attached image). Therefore, you can expect that it will trigger auto-restart at 13 to 14 V due to very high input current.
It would be really great if you could share your schematic diagram, PCB layout (Gerber files preferred), transformer datasheet (from your manufacturer with actual primary inductance and number of turns of each winding), and the PI Expert file of the design (if you have one) so we can review further your design and give feedback. Please also share the input and output specifications of the design.
Thank you and looking forward to your response.
Best Regards,
Tommy