ROHM Semiconductor recently announced that second generation 650V and 1200V SiC products are currently under development. Compared to conventional silicon IGBTs that utilize a high-voltage switching element, switching loss is reduced by over 5 times, contributing to device miniaturization by increasing drive frequency (i.e. through smaller filters and cooling mechanisms) and improving power conversion efficiency.
ROHM was the first to develop a 'full SiC' power module with internal power elements comprised solely of SiC power devices, which it began mass producing in 2012. At present, two types of 1200V/120180A rated power modules are being manufactured using an in-house production system, with 1200V/300A rated power modules scheduled for 2014 and further expansion of rated currents and voltages in the future. These SiC power modules, along with discrete SiC MOSFETs, are already beginning to see adoption globally, primarily in industrial applications such as commercial solar power conditioners and high frequency power supplies.
ROHM is planning a lineup of 1700V breakdown voltage SiC Schottky barrier diodes and SiC MOSFETs, and is currently developing 3rd generation SiC MOSFETs utilizing a trench gate structure that significantly reduces on-resistance per chip area. This technology is expected to accelerate the adoption of SiC by lowering on-resistance and decreasing chip costs.
SiC power devices that provide small switching loss are particularly effective in fields that require both high breakdown voltage and high frequency operation. However, there are still a number of areas in which silicon power devices are utilized due to their superior price point. As a result, ROHM is continuing to develop unique products in the conventional silicon power device sector, such as a 'Hybrid MOS' that features the best characteristics of both MOSFETs and IGBTs.
For silicon IGBTs, ROHM offers a wide range of hybrid products that leverage the company's expertise as a manufacturer of both individual discrete semiconductors and integrated semiconductor components. Below is an introduction of ROHM's silicon IGBT power device product lineup.
ROHM has commercialized two types of 650V breakdown voltage IGBT devices. One, the RGTH series, provides low saturated voltage characteristics (1.6V typ. at rated current) and is designed in such a way that puts a priority on high-speed switching performance demanded for converter circuits. This makes them ideal for power factor correction (PFC) circuits in switching power supplies, boost circuits for solar power generator power conditioners, and the like. The other type the RGT series delivers low saturated voltage characteristics along with short-circuit handling capability (5 ), which is particularly required for inverter circuits in air conditioners, large household appliances such as washing machines, solar power conditioners, and welders. Both series include an ultra-high-speed soft recovery FRD.ROHM plans to gradually expand its product lineup with a 1200V breakdown voltage series as well as products that comply with AEC-Q101 for automotive use.
An IPM (Intelligent Power Module) that integrates an individual IGBT with superior low saturated voltage characteristics, ultra-high-speed soft recovery FRD, gate drive IC, and bootstrap diode in an inverter configuration has also been added to the product lineup. Key features are as follows: The gate drive IC adopts a 600V SOI process that prevents problems caused by latch up; Inrush current is suppressed while stability of the floating power supply on the ARM side achieved using a proprietary current limiting system for the current limiting resistance of the bootstrap circuit; Multiple protection functions are implemented, such as UVLO, short circuit protection, and temperature detection, increasing reliability; Available in a class-leading isolated low thermal resistance ceramic package.
Mass production began in 2014 for two series optimized for large household appliances and smaller industrial motor drive applications: a 'low-speed switching drive series' featuring reduced saturated voltage VCEsat ideal for drive operations at low carrier frequencies (46kHz), and a 'high-speed switching drive series' that reduces switching loss, enabling compatibility with high carrier frequency drive (1520kHz).