The reference design

The EPC9171 consists of a two-phase interleaving boost converter power factor correction (PFC) stage and an isolated LCC resonant power stage, which makes it suitable for wide output voltage range multi-point applications.

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, 3.2mΩ 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.

It switches at two to three times the frequency of standard silicon MOSFET solutions, which enables the very high-power density. It achieves a power density of approximately 1.1 W/cm³ via GaN power switches operating at high switching frequencies in both the primary and secondary circuits, says the company. It adds that it has 79% higher power density, which is more than recently released 140W USB PD3.1 slim chargers, while providing 240W of output power.

As the cost for 48V batteries continues to decrease, additional applications for AC/DC/SMPS charger applications are emerging. With 240W power, the reference design can be adopted for ultra-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 240W reference design measures 83.7 x 83.7mm.

The EPC9171 evaluation board is available for immediate delivery from Digi-Key Electronics.