GaN reference design supports fast USB charging
GaN design Is the basis for EPC’s universal input USB PD3.1 fast charge reference design. The EPC9171 evaluation board converts 90 to 265V universal AC input to a DC output voltage adjustable over a wide range of 15 to 48V. The reference design can supply 240W maximum output power at 48V output voltage and 5A load current.
The EPC9171 is available now and 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 GaN power switches operating at high switching frequencies in both the primary and secondary circuits.
This 240W reference design measures just 83.7 x 83.7mm and shows 79 per cent higher power density, which is more than recently released 140W USB PD3.1 slim chargers, while providing 100W more power, at 240W output, said EPC.
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 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 of 350 to 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, 3.2 mOhm EPC2218 GaN FETs on the secondary side of the LCC stage. The GaN FETs are driven by fast synchronous rectifier controllers to minimise the losses over the whole output voltage and current range and allow a simple, yet effective, thermal design.
The reference design can be adopted for fast USB charging for laptops, notebooks, and smartphones, but can also extend USB charging to other applications requiring 240W, such as gaming PCs, e-bikes, and e-scooters. The cost of 48V batteries continues to decrease, prompting additional applications for AC/DC/SMPS (switch mode power supplies) charger applications to emerge.
“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. He added that the EPC9171 is “an example of how GaN technology enables miniaturisation, 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 available now for immediate delivery from Digi-Key Electronics.
