The example design, from Renesas, takes up 46% less PCB area than an earlier all-silicon version, said GaN Systems, due in part to switching at 500kHz which allowed a move to smaller 1.3µH inductors.
“A combination of GaN with the automatic phase drop achieves efficient power conversion even at low loads, exceeding 94% efficiency over a 400W to 3kW load range,” according to GaN Systems.
Other components in the design are the ISL78226 six-phase PWM controller, aimed specifically at 48-12V bidirectional converters, and multiple half-bridge drive chips: either the 2A peak ISL78420 or the similar 3A peak source 4A sink ISL78444 – both have a single tri-level PWM input that controls both internal gate drivers, and to this the ‘444 adds adaptive dead-time control.
GaN does not have a proven track record in the notoriously conservative automotive industry.
“Customers in automotive are constantly looking for improvements in power density,” said GaN Systems CEO Jim Witham. “The fact that the design comes from Renesas is significant, as they are a market leader in semiconductor solutions for automotive, with a reputation for understanding the needs of the industry.”
Adaptive dead time function*2 automatically adjusts the dead time for optimal control.
The RL78/F24 MCU supports mode setting and status monitoring of DC/DC converters through the CAN FD
*1 Results compared to 12V/48V Bidirectional DC/DC Converter with Si-MOSFET
*2 Functions included in the ISL78444
For additional information on the GaN Systems device in this solution, see GS61008P 100V Enhancement Mode GaN Transistor.
