GaN and SiC Devices Announced at PCIM
GaN and SiC switches and diodes were announced by several companies at this week’s PCIM event in Nuremberg. International Rectifier and MicroGaN announced new GaN devices while Cree, SemiSouth and TranSiC all made announcements related to SiC.
International Rectifier was showing prototypes of its next-generation GaN FETs. The new 600V, 15A devices will be based on a vertical geometry in contrast with the current lateral devices offered by the company. The diodes and switches will be offered in TO220 package and are designed to be drop-in replacements for Si devices. Availability is scheduled for late 2011.
A more near-term announcement was made by MicroGaN which will have 5A 600V GaN rectifiers available at the end of August with similarly-rated transistors shipping by the end of October. The normally-on switch will feature an on-state resistance of 170 milliohms. Both the diode and switch are expected to be offered as die or in a TO220 package.
MicroGaN’s high-voltage devices are based on a HFET (heterostructure field effect transistor) structure epitaxially grown on six-inch silicon substrates. The company has partnered with Diotec Semiconductor for packaging and testing services. Initial GaN diodes have surpassed a stress test over 800V reverse voltage.
Cree was demonstrating the capabilities of its new 1.7kV SiC Schottky rectifiers that are offered in 10 and 25A versions. According to the company, replacing conventional Si devices with the new 1.7kV SiC devices can enable an increase of switching frequency from about 3kHz up to 15-30kHz, with a corresponding reduction in the size of magnetic and other components. The higher operating frequency is a result of the fact that the faster-switching SiC devices reduce diode switching losses by over 90% and significantly reduce IGBT turn-on losses.
TranSiC announced the availability of its 1.2kV 6A and 20A BitSiC power transistors in plastic discrete packages and a six-pack configuration. The BitSiC is a bipolar junction power transistor and is a normally-off device. The 1.2kV devices have a saturation voltage of 0.75V at a junction temperature of 175°C and can be switched in 20-30 nanoseconds.
SemiSouth presented a side-by-side comparison of the new 1.7kV 550mΩ EM SiC JFET and a 1.5kV EBST in a flyback power converter with an input range of 250-850-Vdc and outputs of 24 and 5Vdc. The SiC device demonstrated 4.5-times lower Rds(on), 84% less total switching losses at low-line, 62% less switching losses at high-line, and sufficient voltage capability to handle inputs up to 1,000V. In addition, a 40°C lower case temperature was measured for the SiC device at high line and full load.