New 200 V eGaN® Devices Double the Performance Edge Over the Aging Silicon Power MOSFET.
Efficient Power Conversion (EPC) is doubling the performance distance between the aging silicon power MOSFET and eGaN ®transistors with 200 V ratings. The new fifth-generation devices are about half the size of the prior generation. This performance boost comes from two main design differences, as shown in figure 1. On the left is a cross-section of the fourth generation 200 V enhancement-mode GaN-on-Si process. The cross-section on the right is the fifth-generation structure with reduced distance between gate and source electrodes and an added thick metal layer. These improvements, plus many others not shown, have doubled the performance of the new-generation FETs.
The first two products, EPC2207 and EPC2215, are shown in figure 2 and are compared against the prior generation eGaN FETs. For example, the EPC2207 is 2.6 mm 2compared with the EPC2010C at 5.8 mm 2, yet the EPC2207 has lower R DS(on), lower Q G, Q GD, and much lower Q OSS.
To illustrate the significant performance advantage over Si power MOSFETs, figure 3 compares both the fourth generation and fifth generation eGaN FETs against a benchmark silicon device, the IPT111N20NFD from Infineon. The EPC2215 has 33% lower R DS(on), yet is 15 times smaller in size. Gate charge (Q G) is more than six-time smaller with the new technology, and like all eGaN FETs, there is no reverse recovery charge (Q RR) enabling lower distortion class D audio amplifiers as well as more efficient synchronous rectifiers and motor drives.
Additional confirmation of the advantages of the new-generation 200 V eGaN FETs seen in the performance graphs in figure 4. Shown is a comparison between the Infineon 200 V MOSFET benchmark device, the older-generation EPC2034C, and the fifth-generation EPC2215. The EPC2215 performs better than the older EPC2034C despite being 60% the size. The Si MOSFET has a clearly inferior performance.
With devices as small as these new generation eGaN FETs, a common question is how well they can dissipate heat in operation. Thanks to the chip-scale packaging, thermal efficiency is much higher than the comparable silicon device in a package. As an example, in figure 5 is a 4 mm 2eGaN FET showing 4 °C/W thermal resistance with 6 W power in the device. We show a simulated image for clarity, but the actual capability of the device was experimentally confirmed.
With the clear superiority of these new 200 V eGaN FETs, one might expect them to be priced at a premium. However, EPC has priced these state-of-the-art transistors comparable with their aging ancestor, the silicon power MOSFET.
The applications for these leading-edge devices include class D audio, synchronous rectification, solar MPPTs (maximum power point tracker), DC-DC converters (hard-switched and resonant), and multi-level high voltage converters.
In figure 6 is a 2.5 kW, 4-level totem pole PFC using only six EPC2215 devices. By stacking the 200 V rated eGaN FETs, the input voltage for this PFC can go up to 400 V and, as shown in figure 7, achieve 99.25% efficiency.
EPC’s fifth-generation eGaN FETs achieve higher performance in a smaller, more thermally efficient size, and at a comparable cost. In addition to the buck converter in figure 4, and the totem pole PFC in figure 6, these new-generation 200 V eGaN FETs are ideal for 49 V OUT synchronous rectification and class d audio applications. The inevitable obsolescence of the aging power MOSFET is becoming more evident every day.
Originally published at https://epc-co.com on August 21, 2020.
