480W, <17 mm, Thin Profile, 94% Efficiency, Fast Transient Response AC/DC SMPS Reference Design
Created: Aug 29, 2018
The TIDA-01495 is a low profile (17 mm height), 94.1% peak efficiency, high power density, universal input, 24-V DC, 480-W output, consumer AC/DC power supply reference design. The circuit consists of a front-end two phase interleaved transition mode (TM) power factor correction (PFC) based on the UCC28063A, which minimizes the PFC inductor dimensions and reduces the EMI filter requirements. The HB-LLC isolated DC/DC stage is controlled by the UCC256301 hybrid hysteritic control LLC controller, which ensures fast transient response resulting in reduced PFC bulk and output capacitor dimension. Phase shedding in the PFC stage and the advance burst mode optimization feature in the LLC stage help in meeting high efficiency at 5% load (230V AC). The UCC24612 multi-mode synchronous rectifier controller realizes proportional gate drive, reducing the conduction losses in the output rectifier of the LLC stage, enabling high efficiency.
This reference design is a thin-profile, 480-W, high-efficiency AC/DC power supply for use in spaceconstrained, high-power-density applications. The design consists of a two-phase-interleaved, critical conduction mode (CrCM) PFC converter, which operates from an input voltage range of 85-V to 265-V ACRMS and generates a 390-V DC bus. The second stage comprises an isolated half-bridge (HB) LLC stage, which generates a 24-V, 20-A nominal output. This design demonstrates high-efficiency operation in a small form factor (185 × 110 × 17 mm) and delivers a continuous 480 W of power over the entire input operating voltage range from 85-V to 265-V AC. The design shows an efficiency greater than 93% for 230- V AC nominal operation and 91% for 115-V AC nominal operation. The UCC28063A PFC integrated circuit (IC) controls the interleaved CrCM PFC stage. Interleaved critical conduction mode (CrCM) and continuous conduction mode (CCM) are the two popular topologies for PFC applications with greater than 300-W output power. CrCM PFC has the advantage of minimizing the turn on losses on the PFC MOSFET and eliminates the reverse recovery on the boost diode to reduce losses. CrCM PFC also has a much smaller inductor value than the CCM PFC. The reduced boost inductor value helps to develop the low-profile magnetics necessary for meeting the thin-profile requirement in the design. By interleaving two CrCM power stages, the effective input ripple current is reduced and helps to minimize the EMI filter requirement. The HB-LLC power stage is controlled through the stage of the art UCC256303 resonant controller which implements current mode control for increased control bandwidth. This increased control bandwidth reduces the PFC bulk and output capacitors required to suppress the AC ripple on the output. To achieve high efficiency, the output of the LLC stage uses synchronous rectification based on the UCC24612 device and the CSD19501KCS MOSFET. The design has low standby power of < 400 mW and meets ENERGY STAR rating requirements as well as 2013 EU eco-design directive ErP Lot 6. The EMI filter is designed to meet EN55011 class-B conducted emission levels. The design is fully tested and validated for various parameters such as regulation, efficiency, EMI signature, output ripple, start-up, and switching stresses. Overall, the design meets the key challenges of industrial power supplies to provide safe and reliable power with all protections built-in, while delivering high performance with low power consumption and low bill-of-material (BOM) cost.