News: Microelectronics
23 March 2022
EPC launches 90–265V universal AC input to 15–48V DC output power supply for USB PD3.1 ultra-fast chargers
Efficient Power Conversion Corp (EPC) of El Segundo, CA, USA – which makes enhancement-mode gallium nitride on silicon (eGaN) power field-effect transistors (FETs) and integrated circuits for power management applications – has announced the availability of the EPC9171, a 90–265V universal AC input to 15–48V DC output power supply designed for USB PD3.1 ultra-fast chargers. This reference design can deliver 240W maximum output power at 48V output voltage and 5A load current. A power density of about 1.1W/cm3 is achieved by employing gallium nitride (GaN) power switches operating at high switching frequencies in both the primary and secondary circuits.
The 240W reference design measures just 83.7mm by 83.7mm and shows 79% higher power density (more than recently released 140W USB PD3.1 slim chargers) while providing 240W of output power (100W more).
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 suitable 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 200kHz, allowing small-physical-dimension PFC inductors. The LCC resonant converter operates in the frequency range 350-580kHz, 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 100V-rated, 3.2mΩ 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 240W 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 240W, such as gaming PCs, eBikes and eScooters. As the cost for 48V 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,” says CEO Alex Lidow. “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.”
The EPC9171 evaluation board is priced at $1440 each and is available for immediate delivery from distributor Digi-Key Electronics Corp.
