Benchmark power DC reference design delivering 240 W

EPC announces the availability of the EPC9171, a 90 V – 260 V universal AC input to 15 V – 48 V DC output power supply designed for USB PD3.1 ultra-fast chargers. This reference design can deliver 240 W maximum output power at 48 V output voltage and 5 A load

1. ³ is achieved by employing gallium nitride (GaN) power switches operating at high switching frequencies in both the primary and secondary circuits.

This 240 W reference design measures a mere 83.7 mm by 83.7 mm and shows 79% higher power density, which is more than recently released 140 W USB PD3.1 slim chargers, while providing 240 W of output power – 100 W more power!

The power supply topology used in the design of the EPC9171 consists of a two-phase interleaving boost converter power factor correction (PFC) stage and an isolated LCC resonant power stage. Unlike the well-known LLC resonant power stages, which suffer from limited output voltage range, the LCC resonant converters are ideal for wide output voltage range multi-point applications.

The EPC9171 is an “all-GaN” solution using GaN devices for PFC, LCC and secondary synchronous rectification. The GaN solution switches at two to three times the frequency of standard silicon MOSFET solutions, which enables the very high-power density. 

For the PFC, GaN power switches operate well above 200 kHz allowing small physical dimension PFC inductors. The LCC resonant converter operates in the frequency range of 350 to 580 kHz, which helps to reduce the size of the power transformer as well as that of the other passive components in the resonant circuit.

The synchronous rectifier stage employs a pair of 100 V rated, 3.2 mΩ EPC2218 GaN FETs on the secondary side of the LCC stage. The GaN FETs are driven by fast synchronous rectifier controllers to minimize the losses over the whole output voltage and current range and allow a simple yet effective thermal design.

With 240 W power, this solution can be adopted not only for ultra-fast USB charging for laptops, notebooks, and smartphones, but can extend USB charging to other applications requiring 240 W, such as gaming PCs, eBikes, and eScooters. As the cost for 48 V batteries continues to decrease, additional applications for AC/DC/SMPS charger applications are emerging.

“eGaN FETs and ICs provide the fast switching, small size, and high efficiency needed to further reduce the size and weight, while decreasing charging time for USB PD3.1 fast chargers,” said Alex Lidow, CEO of EPC. “The EPC9171 is an ideal example of how GaN technology enables miniaturization, very high efficiency, and excellent thermal performance for high-volume charger applications using devices that are lower cost and in stock for immediate delivery.”