Combining Industry-Leading Low Conduction Losses and Fast Switching to Improve Efficiency
The new series achieve industry-leading low conduction losses (VCE (sat) = 1.5 V) and fast switching (tf = 30 to 40 ns). There is a tradeoff relationship between these two characteristics, but by exploiting thin wafer technology, the wafer thickness was reduced by 15% compared with previous devices, and through the use of ROHM’s unique structure with a refined cell design, it was possible to achieve both. The following comparative graph indicates that the RGW series achieves a low switching loss of approximately 800 μJ, even while maintaining a low conduction loss of VCE (sat) = 1.5 V.
Through these improvements to characteristics, in examples of use in an interleaved PFC circuit, efficiency was raised 1.2% under light loading and 0.3% under heavy loading, compared with conventional products.
Fewer Overshoot Suppression Components through Soft Switching
Through optimization of the overall design to realize soft switching, it was possible to reduce by 50% the voltage overshoot that occurs during switching, compared with existing devices of comparable efficiency. As a result, snubber circuits and other components that normally were necessary for overshoot suppression can be eliminated. At the same time, damage, malfunctions and the like are also alleviated, for improvements in equipment safety and reliability.
The following is a comparison of switching overshoot. One method of reducing overshoot is to adjust the value of the gate resistance. In general, overshoot tends to diminish when the gate resistance is increased, but the switching speed declines and switching losses increase. In a comparison of devices with a gate resistance of 10 Ω, the new ROHM product series exhibited half or less of the overshoot of standard products, and convergence was also highly satisfactory. Even when the gate resistance of standard products was increased more than threefold to 33 Ω, the remaining overshoot was still greater than that for the new ROHM products.
Applications and Product Lineup
The current product lineup includes two series: the RGTV series, which features a short-circuit withstand time of 2 μs, and the RGW series, which features fast switching, for a total of 21 models (with one model in development). These products are suitable for use in UPS (uninterruptible power supply) devices, welders, power conditioners and other industrial equipment, as well as general-use inverters, converters, and other power conversion equipment for consumer goods such as air conditioners and IH (inductive heating) products.
RGTV Series (Short-Circuit Tolerance Type)
|IGBT only||With built-in FRD||IGBT only||With built-in FRD|
★ Under development