GA08JT17-247 Datasheet, PDF (8/11 Pages) GeneSiC Semiconductor, Inc. – Normally – OFF Silicon Carbide Junction Transistor

GA08JT17-247
Symbol
Table 2: IX2204 Gate Drive Example Component List
Parameter
Values
Range
Typical
V_GH
Supply Voltage, Driver Output A 15 – 20
+ 20.0
V_GL
Supply Voltage, Driver Output B 5.0 – 7.0
+ 5.0
V_EE
Negative Supply Voltage
-10 – GND - 5.0
Gate Capacitor C_G Selection
V_GH / V_EE
V_GL / V_EE
R_{CG CG}
R_ch
D
I_{G G}
R_G(INT)
S
D_RG R_G(EXT)
Figure 23: Primary gate drive circuit passive components with series gate resistance Schottky rectifier.
An external gate capacitor C_G connected directly to the device gate pin delivers the positive current peak I_G,on during device turn-on and the
negative current peak I_G,off during turn-off. A low value resistor R_CG is connected in series with C_G to damp potential high-frequency oscillation.
A high value resistor R_ch in parallel with C_G sets the SJT gate to a defined potential (-V_EE) during steady off-state.
At device turn-on, C_G is pulled to V_GH which produces a transient peak of gate voltage and current. This current peak rapidly charges the
internal SJT C_GS and C_GD capacitances. A Schottky diode, D_RG, in series with R_G(EXT) blocks any C_G induced current from draining out through
R_G(EXT) and ensures that all of the charge within C_G flows only into the device gate, allowing for an ultra-fast device turn-on. During steady on-
state, a potential of V_GH - V_{GS =} V_GH – 3 V is across C_G. When the device is turned off, C_G is pulled to negative V_EE and V_GS is pulled to a
transient peak of V_GS,turn-off = V_EE – (V_GH – 3 V), this induces the negative current peak I_G,off out of the gate which discharges the SJT internal
capacitances.
External Gate Resistor R_G(EXT) Selection
An external gate resistor R_G(EXT) connected directly to the SJT gate pin acts to deliver a continuous current I_G,steady during steady on-state. The
gate current is determined by:
,
The on-state gate-source voltage V_GS(FWD) can be approximated to 3 V and the Schottky on-state voltage V_Sch can be approximated to 0.3 V
which simplifies the equation to:
3.3
,
The desired I_G,steady is determined by the peak device junction temperature T_J during operation, drain current I_D, DC current gain β, and a 50 %
safety margin to avoid operating the device in saturation. I_G,steady may also be approximated from the temperature dependent on-state curves of
the device in Figures Error! Reference source not found. – Error! Reference source not found., provided that a 50 % increase is given.
Symbol
C_G
R_CG
R_ch
R_G(EXT)
R_G(INT-ON)
D_RG
Table 3: Passive Output Component List
Parameter
Range
Values
Typical
Gate Capacitor, External
5 – 20
10
Damping Resistor of Gate Capacitor
0.5 – 2.0
1.0
Charging Resistor
500 – 10k
1k
Gate Resistor, External
0.4 – 5
2
Gate Resistance, Internal, On-State
0.5 – 1.5
0.9
Schottky Diode of Gate Resistor
--
--
Units
nF
Ω
Ω
Ω
Ω
Aug 2014
http://www.genesicsemi.com/commercial-sic/sic-junction-transistors/
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