what is sic mosfet?

2025-06-03 18:57

Characteristics of SiC MOSFETs

1.The on-state resistance changes little with temperature, and the on-state impedance remains low at high temperatures, allowing it to operate well in harsh environments
2.As the gate voltage increases, the on-state resistance becomes smaller, showing behavior closer to a voltage-controlled resistorTurn-on requires relatively small gate charge, and overall driving power is low. Its body diode has a higher Vf, but very good reverse recovery characteristics, which can reduce turn-on losses.
3.It has smaller junction capacitance, faster turn-off speed, and lower turn-off loss.
4.Switching loss is small, enabling high-frequency switching operation, which allows passive components such as filters to be miniaturized and improves power density.
5.The turn-on voltage is higher than that of Si devices. It is recommended to use Vgs of 15V, 18V, or 20V. Although the threshold voltage is only 2.7V, full turn-on can only be achieved when the gate drive voltage reaches 15V to 20V.
6.It has slightly poorer resistance to false triggering. When used in bridge circuits, an active clamping circuit or negative voltage should be applied to prevent false triggering.

High dv/dt causes false turn-on of SiC MOSFET

Application Characteristics

SiC MOSFETs offer superior switching performance and higher thermal conductivity, enabling more compact and efficient power systems in EVs, solar inverters, and industrial drives.

Drive Requirements

1.The trigger pulse should have a relatively fast rise time and fall time, with steep leading and trailing edges.
2.The impedance of the drive circuit should not be too high, so that the gate capacitance can be quickly charged during turn-on and quickly discharged during turn-off.
3.The drive circuit should be able to provide sufficiently large drive current.
4.The drive circuit should be able to provide sufficiently high drive voltage to reduce the conduction loss of the SiC MOSFET.
5.The drive circuit should use negative voltage for turn-off to prevent false turn-on and enhance anti-interference capability.
6.The parasitic inductance of the entire gate drive loop should be small, so that the gate capacitance can be quickly charged during turn-on and quickly discharged during turn-off.
7.The peak current (Imax) of the drive circuit should be larger to reduce the duration of the Miller plateau and improve switching speed.

Comparison of Power Semiconductor Devices
Parameter	Si MOSFET	Si IGBT	SiC
Switching Frequency	High (>20 kHz)	Medium/Low (5 kHz - 20 kHz)	High (>50 kHz)
Basic Protection	None	Desaturation protection, Miller clamp	Current sensing, Miller clamp
V_DD Maximum Rating	20 V	30 V	30 V
V_DD Clamping	0 - 20 V	10 - 20 V	-5 to 25 V
Operating V_DD	10 - 12 V	12 - 15 V	15 - 18 V
UVLO (Undervoltage Lockout)	8 V	12 V	12 - 15 V
CMTI (Common Mode Transient Immunity)	50 - 100 V/ns	< 50 V/ns (less critical)	> 100 V/ns
Propagation Delay	The lower, the better (<50 ns)	Not critical	The lower, the better (<50 ns)
Power Rail Voltage	Up to 650 V	> 650 V	> 650 V
Typical Applications	Power supplies (servers, data communication), telecom, industrial automation, EV/HEV on-board chargers, solar microinverters and string inverters (<3 kW), 400 V to 12 V DC/DC converters in vehicles	Motor drives (AC motors), UPS, central and string solar inverters (>3 kW), automotive traction inverters	PFC power supplies, photovoltaic inverters, used in EV/HEV DC/DC converters and traction inverters, motor drives, rail applications