GA50JT17-CAL Datasheet, PDF (5/8 Pages) GeneSiC Semiconductor, Inc. – Normally – OFF Silicon Carbide Junction Transistor

GA50JT17-CAL
Section V: Gate Drive Theory of Operation
The SJT transistor is a current controlled transistor which requires a positive gate current for turn-on as well as to remain in on-state. An ideal
gate current waveform for ultra-fast switching of the SJT, while maintaining low gate drive losses, is shown in Figure 11.
Figure 11: Idealized Gate Current Waveform
Gate Currents, I_G,pk/-I_G,pk and Voltages during Turn-On and Turn-Off
An SJT is rapidly switched from its blocking state to on-state, when the necessary gate charge, Q_G, for turn-on is supplied by a burst of high
gate current, I_G,on, until the gate-source capacitance, C_GS, and gate-drain capacitance, C_GD, are fully charged.
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The I_G,pon pulse should ideally terminate, when the drain voltage falls to its on-state value, in order to avoid unnecessary drive losses during
the steady on-state. In practice, the rise time of the I_G,on pulse is affected by the parasitic inductances, L_par in the package and drive circuit. A
voltage developed across the parasitic inductance in the source path, L_s, can de-bias the gate-source junction, when high drain currents begin
to flow through the device. The applied gate voltage should be maintained high enough, above the V_GS,ON level to counter these effects.
A high negative peak current, -I_G,off is recommended at the start of the turn-off transition, in order to rapidly sweep out the injected carriers from
the gate, and achieve rapid turn-off. While satisfactory turn off can be achieved with V_GS = 0 V, a negative gate voltage V_GS may be used in
order to speed up the turn-off transition.
Steady On-State
After the device is turned on, I_G may be advantageously lowered to I_G,steady for reducing unnecessary gate drive losses. The I_G,steady is
determined by noting the DC current gain, h_FE, of the device
The desired I_G,steady is determined by the peak device junction temperature T_J during operation, drain current I_D, DC current gain h_FE, and a
50 % safety margin to ensure operating the device in the saturation region with low on-state voltage drop by the equation:
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1.5
Aug 2014
http://www.genesicsemi.com/high-temperature-sic/high-temperature-sic-bare-die/
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