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Custom Gate Drive Resistors
Selecting Gate Drive Resistors
Figure 30 below shows a basic N-channel FET drive circuit. R
Gate Drive Resistor. Its value affects the switching speed and therefore switching
loss of the FET. The drive voltage (V
threshold voltage (V
turn off the FET. The gate drive must have capability to sufficiently charge the
FET input capacitance.
Figure 30 Basic N-channel FET Drive Circuit
All of the PD1000- 665xx Gate Drive Modules use a Texas Instruments UCC5390
Gate Drive IC.
Proper selection of a gate drive resistor affect the following three things:
Low Gate Resistor Values
Small gate resistor values increase the switching speed of a FET making it
susceptible to voltage surge and oscillation and ultimately device failure. Too
small of a gate drive resistor results in overshot in the gate drive voltage (V
R
G
device resistance is insufficient to dampen oscillation.transient voltage spikes or
excessive gate drive voltage and could puncture the gate-source oxide
destroying the device.
High Gate Resistor Values
Large gate resistor values decrease switching speed of the device resulting in
increased power loss, a reduction in performance, and potential heat issues. Too
high of a value over-damps the oscillation and extends the switching times.
68
) to turn on the FET and sufficiently low enough to fully
TH
– drive current
– gate-drive power dissipation
– rise and fall times.
= 0 , there may unwanted ringing in the gate-source waveform; the internal
) must be sufficiently larger than the FET's
G
I
D
D
C
GD
R
G
G
S
C
GS
Keysight Double-Pulse Test Fixture Installation and Use Guide
Selecting Gate Drive Resistors
is the external
G
C
DS
). At
GS
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