Renesas unveils bidirectional 650V GaN switch
Renesas Electronics has introduced what is claims is the industry’s first bidirectional switch using depletion-mode (d-mode) GaN technology, capable of blocking both positive and negative currents in a single device with DC blocking.
Targeting single-stage solar microinverters, AI data centres and onboard electric vehicle chargers, the high-voltage TP65B110HRU is claimed to dramatically simplifies power converter designs and replaces conventional back-to-back FET switches with a single low-loss, fast-switching, easy-to-drive device.
Today’s high-power conversion designs use unidirectional silicon or SiC switches, which block current in only one direction when in the off state. As a result, power conversion must be divided into stages with multiple switched bridge circuits. For example, a typical solar microinverter uses a four-switch full bridge to convert from DC to DC for the first stage, followed by a second stage to produce the final AC output to the grid.
Even as the electronics industry moves toward more efficient single-stage converters, engineers must work around inherent switching limitations. Many of today’s single-stage designs use conventional unidirectional switches back-to-back, resulting in a four-fold increase in switch count and reduced efficiency.
Bidirectional GaN changes this landscape. By integrating bidirectional blocking functionality on a single GaN product, power conversion can be achieved in a single stage using fewer switching devices. Renesas says that a typical solar microinverter, for example, will require only two high-voltage Renesas SuperGaN bidirectional devices, eliminating the intermediary DC-link capacitors and cutting the switch count by half. In addition, GaN products switch fast, with low stored charge, enabling higher switching frequencies and higher power density. In a real-world single-stage solar microinverter implementation, the company's new GaN architecture demonstrated higher than 97.5 percent power efficiency with the elimination of back-to-back connections and slow silicon switches.
Renesas 650V SuperGaN devices are based on a proprietary normally-off technology described as simple to drive and highly robust. The TP65B110HRU combines a high-voltage bidirectional d-mode GaN chip co-packaged with two low-voltage silicon MOSFETs with high threshold voltage (3V) high gate margin (±20V) and built-in body diodes for efficient reverse conduction.
Compared with enhancement mode (e-mode) bidirectional GaN devices, the Renesas bidirectional GaN switch offers compatibility with standard gate drivers that require no negative gate bias. This is said to translate to a simpler, lower-cost gate loop design and fast, stable switching in both soft and hard switching operation without a performance penalty. Power conversion topologies that require hard switching, such as the Vienna-style rectifier, can benefit from its high dv/dt capability of >100 V/ns, with minimum ringing and short delays during on/off transitions. The Renesas GaN device enables true bidirectional switching with high robustness, high performance and ease of use.
“Extending our SuperGaN technology to the bidirectional GaN platform marks a major shift in power conversion design norms,” said Rohan Samsi, VP, GaN Business Division at Renesas. “Customers can now achieve higher efficiency with fewer switching components, smaller PCB area and lower system cost. At the same time, they can accelerate design by leveraging Renesas’ system-level integration with gate drivers, controllers and power management ICs.”
