Can SiC MOSFET be connected in parallel and used?

SiC MOSFET can be connected in parallel and used as well as Si MOSFET.

For precautions on the parallel connection of MOSFETs, refer to MOSFET Application Notes: “Parasitic Oscillation (Power MOSFET Paralleling)" on the Website of Toshiba Electronic Devices & Storage Corporation.

In the case of SiC MOSFET, there are three points to be further noted.

1. Care must be taken because the on-resistance (RDS(ON)) of SiC MOSFET is sensitive to temperature. Since the on-resistance consists of a channel resistance component with a negative temperature coefficient and a drift layer resistance component with a positive temperature coefficient, current imbalance may occur because the temperature coefficient over the entire temperature range is not always positive as shown in Figure 1.

Figure 1(a). R<sub>DS(ON)</sub> - T<sub>a</sub> Characteristics (@I<sub>D</sub> = 10A) (TW060Z120C)
Figure 1(a). RDS(ON) - Ta Characteristics (@ID = 10A) (TW060Z120C)
Figure 1(b). R<sub>DS(ON)</sub> - T<sub>a</sub> Characteristics (@I<sub>D</sub> = 18A) (TW060Z120C)
Figure 1(b). RDS(ON) - Ta Characteristics (@ID = 18A) (TW060Z120C)

2. As shown in Figure 2, when the gate-source voltage (VGS) drops below 18V, the drain current is suppressed and RDS(ON) increases rapidly. This can cause current to be concentrated in a particular MOSFET. Therefore, VGS of Toshiba’s third generation SiC MOSFET should be designed at 18V or higher.

Figure 2. R<sub>DS(ON)</sub> – V<sub>GS</sub> Characteristics (TW060Z120C)
Figure 2. RDS(ON) – VGS Characteristics (TW060Z120C)

3. As shown in Figure 3, Toshiba’s third generation SiC MOSFET has a built-in SiC Schottky barrier diode (SBD) connected in parallel with pn junction body diode. Because the forward voltage (VF) of SiC SBD has a positive temperature coefficient, this SBD ensures a stable current balance.
For this reason, unbalance is less likely to occur in the third generation SiC MOSFET than in Si MOSFET when applying current from the source to the drain. It facilitates heat dissipation design, circuit design and board design.

Figure 3. The third generation SiC MOSFET Equivalent Circuit
Figure 3. The third generation SiC MOSFET Equivalent Circuit

Related links

The following documents also contain related information.

Application Notes

Product page Si MOSFETs
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