9015 Datasheet, PDF (6/7 Pages) List of Unclassifed Manufacturers – QUAD NOR GATE

Figure 4(b) shows that at even nominal line input voltage of 220V AC, the peak drain-to-
source voltage of the MOSFET is at least 600V. The power QFET FQP7N80 is adequate for
this switching condition.
Part
Value
Part
Q1
FQP7N80
R16
IC1
KA3842B
R17
IC2
KA7912
VR18
IC3
KA431
R19
R1
220KΩ (1W) R20
R2
150KΩ (1W)
C1
R3
150KΩ (1W)
C2
R4
150KΩ (1W)
C3
R5
150KΩ (1W)
C4
R6
12KΩ (1/4W)
C5
R7 2.7KΩ (1/4W) C6
R8 100KΩ (1/4W) C7
R9 100KΩ (1/4W) C8
R10 7KΩ (1/4W)
C9
R11
33Ω (1/4W)
C10
R12
1KΩ(1/4W)
C11
R13 10KΩ(1/4W) C12
R14
0.3Ω (1W)
C13
R15
1KΩ(1/4W)
C14
Value
10KΩ (1/4W)
1KΩ (1/4W)
1KΩ (1/4W)
2.2KΩ (1/4W)
2.2KΩ (1/4W)
0.47µF
0.22µF
0.33µF
0.33µF
220µF
223
102
47µF
561
222
471
2200µF (25V)
2200µF (25V)
470µF (25V)
Part
C15
C16
C17
C18
OP
T1
L1
L2
L3
L4
ZD1
D1~3
D4
D5
D6
D7
D8
Fuse
Value
470µF (25V)
3300µF (10V)
3300µF (10V)
104
PC817
Transformer
Line Filter
3µH
Coupled Inductor
10µH
1N4749
1N4937
1N4148
FYPF1010DN(100V/10A)
FYAF3040DN(40V/30A)
1N4937
FR304
3A / 250VAC
Summary
This application note describes ways in which the Fairchild Semiconductor power QFET may
be used in switched mode power supplies. An illustration of this application is a 180W, 100kHz
forward type power supply using a single 800V rated QFET (FQP7N80) to provide regulated
three output voltages. Because the performance of a power supply of this type depends on
various factors such as PCB layout, transformer construction, and switching device etc., the
stated performance results have to be regarded as benchmarks and not absolutes. The other
series of high voltage rated QFETs offered by Fairchild Semiconductor (700, 800, and 900V
ratings) allows designers to improve the performance of a switched mode power supply by sig-
nificantly reducing gate charge and on-resistance.
References
1. Switch Mode Power Supply, Hee Jun Kim, Sung An Dang, 1993
2. Practical Switching Power Supply Design, Marty Brown, Academic Press, San Diego,CA.
3. Power Supply Cookbook, Marty Brown, Butterworth Heinemann, 1994
6
Rev. B, July 2000