Power


GaN takes on lower voltages G


By Alex Lidow Ph.D., CEO and co-founder, Efficient Power Conversion


allium Nitride (GaN) power transistors have been in mass production since the launch of the EPC1001 in March 2010[1] Since that time billions of GaN


.


transistors have been used in everything from mobile phones, fast chargers, humanoid robots, automobiles, AI power supplies, and satellites, just to name a few.


The applications that adopted GaN did so because silicon MOSFETs could not meet the performance or cost requirements of the end users. These applications, however, primarily used GaN transistors in the 100 V to 650 V range. What about lower voltages? The performance differential between 100 V GaN and the best MOSFET can be seen in table 1. This voltage range is typically used in DC- DC converters with input voltages between 36 V and 60 V, or in brushless DC (BLDC) motor drives in that same voltage range. In this table the three key metrics of cost and performance are compared. Cost is reflected in dies size for a given on-resistance (RDS(on)


x Area). Switching


performance can be compared using two metrics, RDS(on)


x QGD , and RDS(on x QOSS . The


former gives an indication of switching losses in systems that switch with abrupt transitions, or “hard switching”. The latter figure of merit (FOM) gives an indication of switching losses in systems that have resonant or “soft” switching. As shown in table 1, the EPC2367[2] from Efficient Power Conversion (EPC) has a clear advantage over the best silicon MOSFET in all three categories. This has resulted in the majority of new high-performance designs at 100 V to migrate away from the ageing MOSFETs.


Until recently, the same was not true for GaN devices rated at 40 V such as typically used in DC-DC converters with 12 V outputs, in USB PD converters up to 26 V, or in low voltage BLDC motor drives. In table 2 there is a comparison between the best MOSFET, the closest GaN competitor, the prior generation 40 V GaN from EPC, and the latest generation 40 V device (EPC2366[3]


). Note that the


EPC2366 is substantially superior in all metrics compared with the best 40 V MOSFET, making it a compelling choice for all new applications requiring this voltage range.


The EPC2366 comes in a compact 2.6 x 3.3 mm QFN package with an exposed back


22 June 2025 Figure 1: The EPC2366 is a 40 V, 0.8 mΩ GaN transistor in a 2.6 x 3.3 mm QFN package. It uses EPC’s latest Generation 7 technology. Components in Electronics www.cieonline.co.uk


Table 1: A comparison between the three key FOMs used to compare 100 V rated transistor performance. Lower numbers indicate better performance.


a simplified circuit diagram of a 1 kW LLC DCDC converter[4]


with a 48 VIN and a 12 VOUT .


This DC-DC converter runs at a nominal 1 MHz resonant frequency making it difficult for MOSFETs with their relatively higher capacitance to achieve the same efficiency as GaN transistors.


Table 2: A comparison between the three key FOMs used to compare 40 V rated transistor performance. Lower numbers indicate better performance.


surface for efficient heat extraction (see figure 1). With an ultra-low RDS(on)


of only


0.8 mΩ and a pulsed current rating of 360 A, this product sets new benchmarks in system performance and power density. This is the


first product to launch using EPC’s seventh generation GaN technology platform. One of the largest applications for 40 V devices is as a synchronous rectifier for a 12 V output DC-DC converter. Figure 2 shows


Figure 3 shows a breakdown of the various components of power loss in this converter. On the left are the power losses using the best 40 V MOSFETs as the synchronous rectifier transistors. The EPC2367 100 V GaN transistor discussed earlier was used as the primary side transistor. Note the total losses in this converter using MOSFETs for synchronous rectification are 22 W, which results in 97.8 per cent efficiency at full load. The largest single source of losses, illustrated by the orange bar, comes from the conduction losses of the secondary side synchronous rectifier transistors (PRDS(on) sec)


.


By replacing the MOSFETs with EPC2366 GaN transistors, the PRDS(on) sec)


losses are cut in


. The GaN transistor has a typical RDS(on) that is half that of the silicon MOSFET despite


half. In addition, the MOSFET footprint is 10 mm2 mm2


EPC2366: 40 V, 68 A Enhancement-Mode GaN Power Transistor compared with the GaN transistor at 8.6


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