By Stockton Wu, Principal System Engineer, Renesas Electronics
Power designers continue to face the familiar challenge of how to deliver more power in less space without sacrificing efficiency or creating a thermal problem. Achieving this is especially important in 48V architectures, where the intermediate bus often must be stepped down efficiently to 12V or lower rails.
In this scenario, questions arise around what happens when a designer increases the switching frequency to reduce passive component size.
With conventional Si MOSFETs, the resulting switching losses can reduce efficiency and increase thermal challenges, leading to the question of whether low-voltage GaN can provide the additional design margin needed to improve this trade-off.
Evaluating Low-Voltage GaN in a 48V to 12V Power Platform
To answer this question, we evaluated a practical 48V to 12V DC/DC converter and compared measured results from GaN and Si MOSFET implementations. For this evaluation, we used a synchronous buck converter based on two Renesas RTP100E005G1FL 100V, 5mΩ GaN FETs and the RRP68150 half-bridge GaN gate driver, as shown in Figure 1.
The EVB-RTP100E005G1FL evaluation board integrates power devices, a gate driver, an inductor, input and output capacitors, and accessible measurement points. This provides a practical platform for evaluating efficiency, power loss, switching behavior, and thermal performance. Figure 2 shows the 3.3mm x 3.3mm FCLGA package of the GaN FET.
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