DN05029/D - 12 Volt, 30 Watt, Off-line Mini-Forward Converter Design Note

DN05029/D, Design Note describes a simple, low cost, high performance, off-line forward converter power supply using NCP1251B flyback controller (TSOP6 package), NDD04N60 D-Pak Mosfet, and the NCP431 programmable zener (SOT23 package). This design is an extension of the mini-forward converter design described in Application Note AND8489 in which the NCP1028 monolithic switcher was used as the main controller. The use of an RCD snubber reset type of forward converter allows the extension of the useful duty cycle to over 50% without excessive voltage excursions across the MOSFET. The topology provides lower output ripple and noise, lower EMI generation and slightly higher efficiency than an equivalent 12V/2.5A flyback topology