The two-phase 48 to 12V bi-directional converter delivers 1.5kW in a small format for mild-hybrid cars and battery power back-up units.

Two converters to be paralleled to achieve 3kW or three converters can be paralleled to achieve 4.5kW. The board features four EPC2206 100V eGaN FETs and is controlled by a module that includes Microchip’s dsPIC33CK256MP503 16-bit digital controller.

Benefits of a 48V automotive systems include a boost to fuel efficiency, four times the power without increasing engine size and a reduction in carbon dioxide emissions without increasing system costs. Design criteria are size, cost, and high reliability. These systems require a 48 to 12V bi-directional converter, with power ranging from 1.5 to 6kW. EPC eGaN FETs operate with 97% efficiency at 250kHz switching frequency. This enables 800W/phase; in comparison, silicon-based solutions are limited to 600W/phase due to the limitation on the inductor current at 100kHz maximum switching frequency. By using GaN FETs, it is possible to reduce the number of phases from five to four for a 3.5kW converter while increasing efficiency, claims EPC. The efficiency of a four-phase GaN converter operating at 250kHz is 1.5% higher than a five-phase silicon MOSFET-based converter operating at 100kHz.

Overall, the DCDC converter is three times faster, more than 35% smaller and lighter, and offers greater than 1.5% higher efficiency compared to silicon MOSFET solutions. The cost of the overall system is less than that of silicon MOSFETs, adds EPC. The efficiency and thermal performance of GaN FETs enables air cooling instead of water cooling and the small size of the GaN FETs reduce heat-dissipating aluminium housing, which contributes additional system cost saving.

The EPC9137 demonstration board is available for immediate delivery from Digi-Key.