AN804 Vishay Siliconix, AN804 Datasheet - Page 3

• Manufacturer Part Number: AN804
• Description: P-Channel MOSFETs/ the Best Choice for High-Side Switching
• Manufacturer: Vishay Siliconix

Half-Bridge (Totem Pole)
A high-side p-channel MOSFET and a low-side n-channel
MOSFET tied with common drains (Figure 5) make a superb
high-current “CMOS equivalent” switch. One fault common to
such circuits has been the excessive crossover current during
switching that may occur if the gate drive allows both
MOSFETs to be on simultaneously.
Properly driving the MOSFET gates can minimize unwanted
crossover current at high supply voltages (both +V
(Figure 6).
Document Number: 70611
10-Mar-97
+15 V
–15 V
I
DD
FIGURE 5. Low-Voltage Complementary
TTL
MOSPOWER Array
FIGURE 6. High-Voltage Complementary Pair Driven by Logic-Compatible MOSFET
N-Channel
+V
–V
DD
DD
P-Channel
N-Channel
+15 V
–15 V
R2
V
DD
OUT
and –V
DD
Z1
R1
R3
)
A resistively-coupled lower-power complementary pair
offers extremely low crossover current when the output stage
uses high-power MOSFETs. The Zener, Z1, and resistors, R1
and R3, act as a level shifter, properly driving the low-power
MOSFETs. The Zener may be selected according to the
equation
V
where +V
Whatever crossover current that might occur in the low-power
drivers is dramatically reduced by the series resistor, R4.
Additionally, driving the high-power complementary pair using
this resistor divider scheme all but eliminates crossover
current in this critical output driver. This increases both the
driver’s efficiency and its reliability.
ZENER
R4
Number
Si9939DY
Si9942DY
Si9928DY
Part
= 2 V
DD
= –V
DD
V
– V
DD
(BR)DSS
30/–30
20/–20
20/–20
th
(V)
www.vishay.com FaxBack 408-970-5600
P-Channel
N-Channel
r
DS
Vishay Siliconix
+V
–V
0.125/0.2
0.05/0.11
0.05/0.1
Max ( )
DD
DD
AN804
3.5/–3.5
I
3/–2.5
5/–3.4
D
(A)
3