5

Application Considerations for SiC MOSFETs

January 2011

CPWR-AN08, REV -

Application Considerations for SiC MOSFETs -

January 2011

This document is provided for informational purposes only and is not a warranty or a specification.

For product specifications, please see the data sheets available at www.cree.com/power. For warranty

information, please contact Cree Sales at PowerSales@cree.com.

Figure

The inductive turn-off losses versus temperature of the

IGBTs are shown in Figure 6. The freewheeling diode

Schottky diode. The turn-off losses of the IGBTs are significantl

strongly increase with temperature. This is due to the tail loss inherent with IGBTs. The NPT IGBT is

significantly better than the TFS IGBT. However, the NPT IGBT conduction losses are much higher than

the CMF20102D. The TFS IGBT conduction loss is lower than the

the highest of the three.

Turn-off Loss

Figure 6: Switching loss vs. temperature comparison (V

To achieve fast switching time, the gate drive interconnections need to have minimum parasitics,

especially inductance. This requires the gate driver to be located as close as possible to the

CMF20120D. Care should be exercised to minimize or eliminate r

be achieved by selecting an appropriate external gate resistor.

certain amount of turn-off snubbing that reduces voltage overshoot and ringing. As with any majority

carrier device, the CMF20120D has no tail, so the amount of drain voltage overshoot and parasitic

ringing is noticeably higher. The higher ringing is of concern because the lower transconductance and

low threshold voltage of the CMF20120D

di/dt can couple back to the gate circuit through any common gate/source inductance.

connection for the gate drive is recommended, especially if the gate driver cannot be located clos

CMF20120D. Ferrite beads (nickel-

are helpful to minimize ringing while maintaining fast switching time

high value resistor (10kΩ) between gate and source in order to prevent excessive floating of the gate

during system power up propagation delays.

Like any other power MOSFET, the

that has a 2.5 – 2.7 V built-in voltage, but a

to a Si SJMOSFET. Use of this diode is not recommended due to its high forward drop. An exte

Schottky diode is suggested. Cree’s C2D10120A is the recommended device until such time that a

247 single co-packaged part is released.

Conclusions:

6

off losses versus temperature of the CMF20120D compared with the TFS and NPT

The freewheeling diode used with all devices was a 1.2 kV, 10A SiC

off losses of the IGBTs are significantly higher than the CMF20120D

strongly increase with temperature. This is due to the tail loss inherent with IGBTs. The NPT IGBT is

significantly better than the TFS IGBT. However, the NPT IGBT conduction losses are much higher than

The TFS IGBT conduction loss is lower than the NPT IGBT, but the switching loss is

Turn-on Loss

To achieve fast switching time, the gate drive interconnections need to have minimum parasitics,

especially inductance. This requires the gate driver to be located as close as possible to the

. Care should be exercised to minimize or eliminate ringing in the gate drive circuit. This can

be achieved by selecting an appropriate external gate resistor. The silicon IGBT current

off snubbing that reduces voltage overshoot and ringing. As with any majority

has no tail, so the amount of drain voltage overshoot and parasitic

ringing is noticeably higher. The higher ringing is of concern because the lower transconductance and

of the CMF20120D reduces gate noise immunity. The high level of drain current

di/dt can couple back to the gate circuit through any common gate/source inductance. A Kelvin

recommended, especially if the gate driver cannot be located clos

-zinc recommended) in lieu of or in addition to an external gate resistor

are helpful to minimize ringing while maintaining fast switching time. It is also recommended to connect a

en gate and source in order to prevent excessive floating of the gate

gation delays.

power MOSFET, the CMF20102D has a body diode. The body diode is a SiC PN

in voltage, but a substantially lower reverse recovery charge when compared

to a Si SJMOSFET. Use of this diode is not recommended due to its high forward drop. An exte

Cree’s C2D10120A is the recommended device until such time that a

ed part is released.

compared with the TFS and NPT

used with all devices was a 1.2 kV, 10A SiC

CMF20120D and

strongly increase with temperature. This is due to the tail loss inherent with IGBTs. The NPT IGBT is

significantly better than the TFS IGBT. However, the NPT IGBT conduction losses are much higher than

, but the switching loss is

)

To achieve fast switching time, the gate drive interconnections need to have minimum parasitics,

especially inductance. This requires the gate driver to be located as close as possible to the

inging in the gate drive circuit. This can

current tail provides a

off snubbing that reduces voltage overshoot and ringing. As with any majority

has no tail, so the amount of drain voltage overshoot and parasitic

ringing is noticeably higher. The higher ringing is of concern because the lower transconductance and

reduces gate noise immunity. The high level of drain current

A Kelvin

recommended, especially if the gate driver cannot be located close to the

zinc recommended) in lieu of or in addition to an external gate resistor

It is also recommended to connect a

en gate and source in order to prevent excessive floating of the gate

is a SiC PN diode

substantially lower reverse recovery charge when compared

to a Si SJMOSFET. Use of this diode is not recommended due to its high forward drop. An external SiC

Cree’s C2D10120A is the recommended device until such time that a TO-