Startup failed at high AC Voltage
Hi,
we have created a design with TOP270 and stacked fet for ac 230v..480v to 24vdc/48w.
The design runs very well but now in series several parts will fail with an error.
Switching on at 230v is ok, but switching on at 440v every 5..10 trials TOP270 will not start.
Restart is only possible if input capacitor goes <50v. Resistor to pin X ist 10M.
Did you have any idea for the reason of failure?
regards
Comments
Hi PI-Sarek,
i have added a schematic. I will verify gate-source voltage...
Regards Perry
| Attachment | Size |
|---|---|
| Pi TOP270K with stacked fet (83.98 KB) | 83.98 KB |
Gate voltage of stacked fet is ok. Error occurs after switching supply on while dc voltage just is decreasing...
Regards Perry
Hi, i added screenshots from startup. Failure occurs only when voltage on capacitor is low (25v).
After failure a restart is only possible when voltage on capacitor is zero.
regards Perry
| Attachment | Size |
|---|---|
| Switch-on-ok.jpg (72.87 KB) | 72.87 KB |
| Switch-on-fault.jpg (71.86 KB) | 71.86 KB |
Which Capacitor in the schematic are you talking about?Could you please remove R97 and C39 , see if you still see the Issue.
Please go through one of reference design idea below:
Hi,
When designing a StackFET circuit it is important to ensure that the MOSFET stacked on top of the Integrated Switcher has sufficient gate drive. Have you verified the gate source voltage of the MOSFET?
Please provide a complete schematic of your design so that we can help you further.
Best Regards,
PI-Sarek