Datasheet
SLUS431A – MAY 2000 – REVISED DECEMBER 2000
12
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
The evaluation circuit of UCC3961 as the primary-side startup circuit and UCC38C45 as the secondary-side
controller is shown in Figure 2.
UDG–99041
1
3
2
4
5
7
6
14
12
13
11
10
8
9
1
3
2
4
8
6
7
5
VREF
OUT
GND
COMP
FB
CS
RT
RT
80 k
Ω
1
µ
F
200
Ω
300
Ω
100 pF
1
µ
F
0.1
µ
F
1 nF
3.9 k
Ω
6.2 k
Ω
27 k
Ω
22 k
Ω
6.8 k
Ω
2.7 nF
0.1
µ
F
4.7
µ
F
0.1
µ
F 36 k
Ω
1000 pF
1000 pF
36 k
Ω
10 k
Ω
470
µ
F
UP4–101
MUR610
IRF530
0.5
Ω
MUR110
4.7 k
Ω
1 k
Ω
10
Ω
470
µ
F
SD
OVS
REF
AGND
SS
FB
ISET
VDD
UVS
OUT
PGND
VS
CS
START
UCC3961
OUT
12 V
0.1
µ
F
12 V
V
IN
L
M
= 5.4
µ
H
UCC38C45
VDD
Figure 2. Evaluation Circuit of UCC3961