TIDT278 April 2022
This tiny 4-W flyback converter with additional three isolated output windings generates four outputs in total. With a windings ratio of 1:1 in between the primary and auxiliary winding, the conventional RCD snubber could be replaced by an AC flying capacitor providing better efficiency and lower EMI, but this requires the lowest leakage inductance.
The input is in the automotive range of 7 V up to 42-V surge, three outputs are post-regulated by LDO to improve line and load regulation and power supply ripple rejection (PSRR).
A differential input filter has been added to attenuate conducted emissions, and a Schottky rectifier acts as reverse-polarity protection.
As for all multi-output primary-side regulated approaches using general purpose controllers no load at the auxiliary windings is a limitation for cross regulation.