ROHM has added a new lineup, the R60xxMNx series, to its PrestoMOSTM line featuring industry-fastest trr (reverse recovery time). PrestoMOS products sharply reduce switching losses by reducing trr by approximately 60% relative to standard super-junction MOSFETs, and have driven reduction of the power consumption of motor drivers and inverter applications in white goods, industrial equipment, and other areas. The new R60xxMNx series was developed so as to retain the fast trr of the preexisting R60xxFNx series, while further reducing the ON-resistance and Qg (total gate charge) with the goal of reducing losses. In general, there is a tradeoff between ON-resistance and Qg, but through ROHM's unique process technology and optimization, even higher levels for both were achieved simultaneously.
* PrestoMOS is a trademark of ROHM Co., Ltd.
Reliability Secured through Improved Short-Circuit Capacity
The short-circuit capacity is the time until breakdown during short-circuiting of a MOSFET. Normally, when a short-circuit occurs a large current that exceeds the design value flows, abnormal heat generation occurs, leading to thermal runaway and possibly culminating in breakdown. There is a tradeoff between increasing the short-circuit capacity and other performance parameters, beginning with the ON-resistance. In the R60xxMNx series, the short-circuit capacity, which is an important subject for study in motor-driven applications, was boosted by optimizing the parasitic bipolar transistor that is the cause of thermal runaway. Thus together with its fast trr values, this series has achieved considerable superiority in short-circuit capacity over competing products.
Suppressing Losses Due to Self-Turn-On
Self-turn-on is a phenomenon that occurs when the Vds of a MOSFET in the OFF-state changes suddenly (when a voltage is applied from 0 V) and charging of the parasitic capacitance of the MOSFET causes Vgs to exceed the threshold, so that the MOSFET is briefly turned on. This unwanted ON-time of course results in a loss.
As a representative example, it is known that when the low-side switch in a synchronous rectification converter is in the OFF-state, this phenomenon occurs with the timing at which the high-side switch turns on. Measures employing external circuits, such as to delay the ON-time of the high-side switch and suppress dV/dt or to add external capacitance across the low-side switch gate and source to increase the margin, may be necessary.
The R60xxMNx series reduces losses due to self-turn-on to the lowest possible levels through reduction and optimization of parasitic capacitance.
☆: Under development