Bidirectional GaN switch for high-voltage conversion

Efficiency and component reduction remain key design targets in power electronics used in renewable energy, electric mobility, and digital power infrastructure. In this context, Renesas Electronics Corporation introduced a high-voltage bidirectional GaN switch designed to enable simpler single-stage converter topologies.

Reducing switch count in converter topologies
Most high-power converter designs rely on unidirectional silicon or silicon carbide (SiC) switches that only block current in one direction in the off state. This typically necessitates multi-stage conversion architectures with multiple bridge circuits.

Solar microinverters illustrate this constraint. A typical design uses a four-switch full bridge for DC-DC conversion followed by another stage for DC-AC conversion. Even in single-stage designs, engineers often compensate by connecting conventional switches back-to-back, increasing device count and switching losses.

The bidirectional GaN design integrates reverse blocking capability into a single device, allowing single-stage conversion with fewer switches. In a representative solar microinverter implementation, two Renesas SuperGaN^® bidirectional devices can replace larger switch arrangements while removing intermediate DC-link capacitors.

Switching behaviour and efficiency impact
GaN switching devices support higher switching frequencies due to low stored charge and fast transition behaviour, supporting higher power density designs.

Testing in a single-stage solar microinverter configuration showed conversion efficiency exceeding 97.5 %, supported by the elimination of back-to-back device configurations and slower silicon switches.

This makes the technology applicable in systems such as AI data-center power supplies, onboard EV chargers, and distributed solar converters where switching losses directly influence thermal design and system efficiency.

GaN device architecture and gate drive compatibility
The TP65B110HRU integrates a high-voltage depletion-mode GaN device with two low-voltage silicon MOSFETs. The design features a typical 3 V threshold voltage, ±20 V gate tolerance and integrated body diodes supporting reverse conduction.

Unlike enhancement-mode bidirectional GaN devices, the switch operates with standard gate drivers without requiring negative gate bias. This reduces gate drive complexity and supports stable switching under both hard- and soft-switching conditions.

For hard-switched topologies such as Vienna rectifiers, the device supports dv/dt capability above 100 V/ns, enabling fast transitions with limited ringing and switching delays.

Electrical parameters and integration details
The device supports ±650 V continuous AC/DC operation and ±800 V transient voltages, with a typical RDS(on) of 110 mΩ at 25 °C.

Additional specifications include dv/dt immunity above 100 V/ns, a 1.8 V freewheeling diode voltage drop, and a TOLT top-side cooled package with an industry-standard pinout to support thermal design and PCB compatibility.

Evaluation and reference designs
An evaluation kit (RTDACHB0000RS-MS-1) supports testing across different gate drive configurations, AC zero-crossing detection, and zero-voltage switching (ZVS) implementation.

The device is also part of Renesas system reference designs, including a 500 W solar microinverter and three-phase Vienna rectifier platforms combining compatible controllers, gate drivers and power management ICs to reduce design complexity and integration risk.

Edited by industrial journalist Aishwarya Mambet, with AI-assistance.

www.renesas.com