SN75374_14 Datasheet, PDF (10/19 Pages) Texas Instruments – QUADRUPLE MOSFET DRIVER

SN75374
QUADRUPLE MOSFET DRIVER
SLRS028A − SEPTEMBER 1988 − REVISED NOVEMBER 2004
APPLICATION INFORMATION
driving power MOSFETs
The drive requirements of power MOSFETs are much lower than comparable bipolar power transistors. The
input impedance of an FET consists of a reverse-biased PN junction that can be described as a large
capacitance in parallel with a very high resistance. For this reason, the commonly used open-collector driver
with a pullup resistor is not satisfactory for high-speed applications. In Figure 14a, an IRF151 power MOSFET
switching an inductive load is driven by an open-collector transistor driver with a 470-Ω pullup resistor. The input
capacitance (C_ISS) specification for an IRF151 is 4000 pF maximum. The resulting long turn-on time, due to the
product of input capacitance and the pullup resistor, is shown in Figure 14b.
48 V
5V
M
4
470 Ω
3
48
7
3
TLC555
6
5
21
1/2 SN75447
(a)
IRF151
2
1
0
0 0.5 1 1.5 2 2.5 3
t − Time − µs
(b)
Figure 14. Power MOSFET Drive Using SN75447
A faster, more efficient drive circuit uses an active pullup, as well as an active pulldown output configuration,
referred to as a totem-pole output. The SN75374 driver provides the high-speed totem-pole drive desired in an
application of this type (see Figure 15a). The resulting faster switching speeds are shown in Figure 15b.
48 V
5V
M
4
48
7
3
TLC555
6
5
21
1/4 SN75374
IRF151
3
2
1
0
0 0.5
(a)
Figure 15. Power MOSFET Drive Using SN75374
1 1.5 2
t − Time − µs
(b)
2.5 3
10
• POST OFFICE BOX 655303 DALLAS, TEXAS 75265