This reference design is a compact, high efficiency, 24-V DC, 500-W reference design for industrial AC/DC power supplies. This design consists of a front-end, two-phase interleaved transition mode (TM) power factor correction (PFC) based on the UCC28064A. This minimizes the PFC inductor size and reduces EMI filter requirements. The DC-DC is implemented using the HB-LLC stage implemented using TI’s UCC256301 device. For efficiency improvement, synchronous rectification is used at secondary which uses the UCC24612.
This reference design is a 500-W high efficiency industrial AC/DC power supply. The design consists of a two-phase-interleaved, critical conduction mode (CrCM) PFC converter, which operates from an input voltage range of 85- to 265-V AC RMS and generates a 400-V DC bus. The second stage is made up of an isolated half-bridge LLC stage, which generates a 24-V, 20-A nominal output. Industrial power supplies have requirements of high efficiency over their entire operating voltage range and wide load variations from a 50% to 100% load. This design demonstrates high efficiency operation in a small form factor (155 × 125 mm) and delivers continuous 480 W of power over the entire input operating voltage range from 85-to 265-V AC. It gives an efficiency of > 94.5% for 230-V AC nominal operation and 92% for 115-V AC nominal operation.
Features
- Overall efficiency of 94.5% at full load with peak efficiency > 95%
- Up to 330-W operation without forced cooling
- High power factor > 0.99 and meets PFC regulations and current THD as per IEC 61000-3- 2 Class A
- Meets requirements of conducted emissions standard (EN55011 Class B)
- ZCS avoidance feature and OVP sensing feature in LLC controller improves robustness and protects systems from overcurrent, short circuit, and overvoltage to ensure safety
- Small 160 mm × 80 mm × 35 mm PCB form factor
