Self-resonant reset forward converter with dual-outputs for military application

This paper presents miniature size dual outputs DC-DC converter for military applications. Proposed converter is designed using self-resonant reset forward converter topology followed by fixed high switching frequency (>250 KHz) with UCC28C45 as a PWM controller. The self resonant reset method eliminates power loss in the reset circuit, thus simplifying the circuitry and increasing efficiency. Isolation in control loop is provided by optocoupler as it does an excellent job of isolation, minimizing circuit complexity and reducing cost. The proposed topology is demonstrated with an experimental prototype that delivers dual outputs 5V/3A, 3.3V/4A from an 18-36 V input voltage range with efficiency better than 75%. Meeting Cross regulation in multi-output converter is a very challenging task. The other challenging task was meeting the transient response as per MIL-STD-1275A which requires an application of 100V for 50msec and also meeting the transient response as per MIL-STD-704A, MIL-STD-704D (80V for 100msec) without over designing the converter for such a high voltage. This paper provides a technique to meet these challenges in the MIL-Grade DC-DC Converter. This converter has an inbuilt EMI/EMC filter and is realized in a very small size of 50 mm × 50 mm × 12.5 mm aluminum package.