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Recent data shows that the new TO-247-4L package can overcome the adverse effect of source connection inductance on switching speed in superjunction MOSFETs.
Based on their operating principle, superjunction MOSFETs are also called charge-compensation MOSFETs. They can raise MOSFET withstand voltage to 900V because the superjunction provides lower RDS(on), maintaining higher efficiency at any given frequency and resolving the trade-off between on-resistance (RDS(on)) and breakdown voltage.
In practice, however, once MOSFET switching speed reaches a certain limit, the source connection inductance in the device package begins to hold it back and seriously affects switching speed. The following uses Toshiba's simulation analysis as an example to introduce the features of the TO-247-4L package.
Schematic of a MOSFET in a 4-pin TO-247-4L package
SPICE simulation of the TO-247-4L package
Toshiba used the same MOSFET device model to compare and analyze the 4-pin TO-247-4L package and the 3-pin TO-247 package.
First, the source lead is split into two parts, which are then connected to the drain and gate respectively. Experiments found that after the MOSFET turns on, the gate voltage of the 3-pin TO-247 packaged device drops, reducing turn-on speed. In the 4-pin package, the VGS voltage across the MOSFET is almost equal to VDRV.
This data shows that, compared with 3-pin packaged MOSFETs, the 4-pin package helps increase MOSFET switching speed.
The simulation also indicates that using the TO-247-4L package helps reduce MOSFET conduction loss. The results confirm that 4-pin packaged MOSFETs switch faster than 3-pin packaged MOSFETs, and conduction loss is reduced by 19% due to the higher switching speed.
Several typical superjunction MOSFETs
On the market, superjunction MOSFETs include ROHM's high-voltage (600V～) power MOSFET products and Toshiba's N-channel planar MOSFET (700V～) series, among others.
4-pin TO-247-4L package used for superjunction MOSFETs
ROHM's PrestoMOS 600V superjunction MOSFETs have a built-in fast diode that maintains an extremely fast reverse recovery time (trr) while increasing design flexibility, helping save energy in motors and inverters. They are well suited for motor drives in white goods such as air conditioners and refrigerators, as well as EV charging piles.
Toshiba's superjunction MOSFETs use the 4-pin TO-247-4L package and offer high speed, high performance, low loss, low on-resistance, and a small package. With withstand voltage of 500V~800V, they reduce conduction loss by 19% and can suppress gate oscillation.
Product and data analysis from multiple MOSFET manufacturers demonstrates that superjunction MOSFETs in the TO-247-4L package can reduce on-resistance and increase MOSFET switching speed.
