Gejian Semi Gate Drivers

Gejian offers gate drivers for various voltage classes to match different power device requirements. The 650V class is designed for low-voltage IGBTs and SiC MOSFets used in 400V DC bus applications such as appliance drives and low-voltage industrial equipment. The 1200V class is the most versatile, suitable for standard industrial IGBTs and SiC MOSFETs in 380V/480V AC and 800V DC bus applications. The 1700V class addresses high-voltage IGBTs used in traction drives and medium-voltage applications. Gejian offers SiC-optimized drivers with features specifically designed for SiC MOSFET requirements such as higher CMTI and Miller clamp. The voltage class refers to the isolation voltage capability between the input and output sides, which should be selected based on the power device's voltage rating with appropriate safety margin.

Select gate driver voltage class based on power device rating: 650V for 400V systems, 1200V for 800V systems. Contact our FAE team for selection guidance.

Gejian gate drivers include comprehensive protection features to ensure reliable operation of power devices. Desaturation Detection monitors the VCE or VDS of the power device during conduction and shuts down the gate drive if the voltage indicates a short circuit condition. Undervoltage Lockout (UVLO) prevents operation if the gate drive supply voltage is insufficient to properly enhance the power device. Miller Clamp provides a low-impedance path to prevent false turn-on from Miller capacitance coupling during high dv/dt switching. Soft Shutdown provides controlled turn-off during fault conditions to prevent voltage overshoots. Overcurrent Protection can be implemented using external current sensing. Fault Reporting provides status indication to the system controller. The specific protection features vary by driver model, with higher-end drivers including more comprehensive protection.

Select gate driver with appropriate protection features for your application. Desaturation detection is essential for IGBTs. Contact our FAE team for protection feature selection.

Gejian offers both single-channel and dual-channel gate drivers to address different application needs. Single-channel drivers control one power switch and are used in applications like boost converters, buck converters, and as building blocks for custom designs. They offer maximum flexibility in system configuration. Dual-channel drivers control two power switches (typically high-side and low-side of a half-bridge) and are ideal for half-bridge and full-bridge topologies. Dual-channel drivers often include shoot-through prevention logic to ensure both switches cannot be on simultaneously. For three-phase inverters, three dual-channel drivers or six single-channel drivers are needed. Dual-channel drivers can reduce component count and simplify layout for bridge topologies. Some dual-channel drivers include additional features like interlock protection and programmable dead time.

Use single-channel for flexibility, dual-channel for half-bridge/full-bridge topologies. Contact our FAE team for topology-specific recommendations.

CMTI (Common Mode Transient Immunity) is a critical parameter for isolated gate drivers, especially when driving SiC MOSFETs. It specifies the maximum rate of change of common-mode voltage (dv/dt) that the isolator can withstand without errors. SiC MOSFETs switch extremely fast, with dv/dt rates exceeding 50V/ns. During switching, the common-mode voltage between the control and power sides changes rapidly. If the gate driver's CMTI is insufficient, this rapid dv/dt can cause glitches or errors in the gate drive signal, potentially leading to shoot-through or improper switching. Gejian SiC-optimized gate drivers offer CMTI ratings of 100kV/μs or higher to handle the fast switching of SiC devices. Standard IGBT gate drivers may have lower CMTI ratings (50kV/μs) which are sufficient for the slower switching of IGBTs but may not be adequate for SiC applications.

Use gate drivers with CMTI >100kV/μs for SiC MOSFETs. Lower CMTI is acceptable for IGBTs. Contact our FAE team for CMTI requirements.

Gate resistor selection involves balancing switching speed, switching losses, and EMI. The turn-on gate resistor (RGon) controls the turn-on switching speed. Lower values provide faster switching with lower switching losses but higher EMI and potential for voltage overshoot. Typical RGon values are 5-22Ω for IGBTs and 2-10Ω for SiC MOSFETs. The turn-off gate resistor (RGoff) controls turn-off speed. Separate RGoff is often used to independently optimize turn-off behavior. RGoff is typically equal to or smaller than RGon for fast turn-off. The gate resistor power rating should be sufficient for the gate drive power (P = Qg × Vgs × fsw). Gate resistor selection should be verified with actual hardware testing, as parasitic inductance and capacitance affect switching behavior. Some applications may benefit from non-linear gate resistors or active gate drive techniques.

Start with 10Ω for IGBTs, 5Ω for SiC MOSFETs. Adjust based on switching waveforms and EMI testing. Contact our FAE team for gate resistor optimization.