The impact of parallel GaN HEMTs on efficiency of a 12-to-1 V buck converter

The impact of parallel GaN HEMTs on efficiency of a non-isolated point of load (POL) converter is investigated. The test results indicate how many parallel GaN HEMTs should be used to achieve maximum efficiency based on load current. Loss calculations and simulations provided initial direction, and ten POL converters were tested-only varying the number of paralleled GaN HEMTs. Each design was tested between 2.5 and 30 A output. Depending on application load and frequency, the optimal combination of GaN HEMTs can be derived from this data. Results indicate that above 19.5 A load, two EPC2015 switches and four EPC2015 synchronous rectifiers (referred to as 2×2015/4×2015) minimizes loss. Below 19.5 A load, a 1×2015/2×2015 HEMT combination minimizes loss. Results presented here should expedite the design process for future engineers seeking greater power supply efficiency with GaN transistors, and it provides novel test data over a large load spectrum, variety of frequencies, and ten combinations of GaN HEMTs in a non-isolated POL converter.