Datasheet
SLRS028A − SEPTEMBER 1988 − REVISED NOVEMBER 2004
11
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
driving power MOSFETs (continued)
Power MOSFET drivers must be capable of supplying high peak currents to achieve fast switching speeds as
shown by the equation:
I
PK
+
VC
t
r
where C is the capacitive load and t
r
is the desired rise time. V is the voltage that the capacitance is charged
to. In the circuit shown in Figure 14a, V is found by the equation:
V = V
OH
− V
OL
Peak current required to maintain a rise time of 100 ns in the circuit of Figure 14a is:
I
PK
+
(3 * 0)4(10
−9
)
100(10
−9
)
+ 120 mA
Circuit capacitance can be ignored because it is very small compared to the input capacitance of the IRF151.
With a V
CC
of 5 V and assuming worst-case conditions, the gate drive voltage is 3 V.
For applications in which the full voltage of V
CC2
must be supplied to the MOSFET gate, V
CC3
should be at least
3 V higher than V
CC2
.