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TOP261EN 66KHZ

Hello, I'm designing a 180W power supply, 12V 15A with TOP261EN at 66khz switching frequency (PIN F and C shorted). Till 120W all ok, but over some instability occurs. The strange thing is that I see switching frequency over 66Khz, sometime over 100khz. I double check pin F and C were shorted and they were. So how is possible the frequency goes over 66khz + jitter when pins F and C are shorted?

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1 reply  |  Created on Jan 29, 2012 23:38 PM by Community Member dbaldacci
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TOP261EN 66KHZ
Posted: Feb 1, 2012 | 09:16 AM

You proably have noise interaction caused by your layout. Make sure C pin capacitor is star grounded to source pin. Also adding an additional 0.1uF capacitor for high frequency noise from c pin to source could help.

Power Integrations Moderator PI-Surak  |  345 posts