GaN Power Devices Achieve a High-Efficiency 48 V, 1.2 kW LLC Resonant Converter in a ⅛th Brick Size
Jul 21, 2022
There is increasing demand for extracting more power from standard 48 V bus converters for server applications' ever-increasing power requirements. GaN power devices allow a designer to achieve a converter's goals: high efficiency, small size & high current handling, ease, and high reliability. To whet your appetite, EPC designed a 1.2 kW resonant converter demo board (EPC9174) in an 1/8th brick form factor that achieves an impressive 97.3% peak efficiency.
The LLC resonant topology of the EPC9174 consists of a full-bridge primary side and a center-tapped secondary side with parallel-connected synchronous rectifiers to reduce the conduction loss. A series-connected 2 × 2:1:1 matrix transformer integrated into a single core is designed. The high output current is distributed among multiple secondary stages, ensuring low interconnect inductance between the transformer and the synchronous rectifiers and reducing winding loss.
eGaN FETs are well suited for soft-switching LLC resonant converters mainly due to the very low gate charge (Qg), the 5 V gate operation, and low output capacitance of the FETs. The EPC9174 uses the 100 V rated 2.2 mΩ EPC2071, and 40 V rated 1 mΩ EPC2066 for the primary and secondary-side power devices, respectively.
The overall power loss and efficiency at 48 V input and 12 V output, including the housekeeping power consumption, is shown in the measured graph below:
The EPC9174 is a 48V input, 1.2 kW output, 4:1 conversion ratio, LLC resonant converter in the ⅛th power brick size designed with GaN FETs to help jump-start your next design.
Schematics, Gerber files, and a Quick Start Guide are available here to help you get going!