Vcc pin capacitor of NCP1239 and NCP1219 flyback controllers

Flyback · 2024-09-05T04:45:50-0700

Hi,
Page 3 of AND9296 says that the Vcc in capacitor of NCP1239 should be high enough so that the NCP1239 does not loose power during light load when it goes into burst mode.
The schematic of page 2 of AND9296 shows the Vcc pin capacitor of NCP1239 (c10) being 47uF.
However, NCP1219 also has non-switching periods during light load, and yet the Vcc pin capacitor for NCP1219 on page 2 of AND8393 is only shown as being 22uF.

Why are they so different?

NCP1219

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwigldH52KuIAxUHa0EAHQ7YGCAQFnoECBUQAQ&url=https%3A%2F%2Fwww.onsemi.com%2Fpdf%2Fdatasheet%2Fncp1219-d.pdf&usg=AOvVaw2jKUCp7iYQ1JEwITXM3igQ&opi=89978449

NCP1239

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjmzv7e26uIAxVOVEEAHfTnF5AQFnoECAsQAQ&url=https%3A%2F%2Fwww.onsemi.com%2Fpdf%2Fdatasheet%2Fncp1239-d.pdf&usg=AOvVaw1Q6oQrLHfe1qmCd09bKihe&opi=89978449

AND9296

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwi397mOzquIAxUiVUEAHRYlFJsQFnoECBQQAQ&url=https%3A%2F%2Fwww.onsemi.jp%2Fpub%2FCollateral%2FAND9296-D.PDF&usg=AOvVaw1p9MsI_9dNFeWzqVHY100L&opi=89978449

AND8393

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjL9JaBzquIAxWPWEEAHQ4HDtgQFnoECBMQAQ&url=https%3A%2F%2Fwww.onsemi.com%2Fdownload%2Fapplication-notes%2Fpdf%2Fand8393-d.pdf&usg=AOvVaw0tg6Sjh_pZMrl4JfJhu0jN&opi=89978449