SLUS223C – APRIL 1997 – REVISED JUNE 2007
www.ti.com
OFFLINE FLYBACK REGULATOR
R1
5
Ω
1W
117 VAC
VARO
VM 68
R12
4.7 kΩ
2W
R2
56 kΩ
2W
C9
3300 pF
600 V
D4
1N3613
T1
D6
U9D946
L1
+6 V
C1
250
µF
250 V
N5
N
P
C10
4700
µF
10 V
D7
UF81002
+12 V
R4
4.7 kΩ
R3
20 kΩ
D2
1N3612
D3
1N3612
N12
N12
C2
100
µF
25 V
C3
22
µF
R9
68
Ω
3W
C4
47
µF
25 V
C12
2200
µF
16 V
C13
2200
µF
16 V
−12 V
D8
UES1002
UC3844
8
R6
10 kΩ
C5
0.01
µF
4
C6
0.0022
µF
5
6
R8
3
USD1120
1 kΩ
C7
470 pF
R13
20 kΩ
R10
0.55
Ω
1W
D8
1N3613
R11
2.7 kΩ
2W
R7
22
Ω
Q1
UFN833
C8
680 pF
600 V
C11
4700
µF
10 V
COM
±12
V COM
2
R5 150 kΩ
1
C14
100 pF
7
NC
Power Supply Specifications
1. Input Voltages
a. 5VAC to 130VA (50 Hz/60 Hz)
2. Line Isolation: 3750 V
3. Switchng Frequency: 40 kHz
4. Efficiency at Full Load 70%
5. Output Voltage:
a. +5 V,
±5%;
1A to 4A load
Ripple voltage: 50 mV P-P Max
b. +12 V,
±3%;
0.1A to 0.3A load
Ripple voltage: 100 mV P-P Max
c. –12 V,
±3%;
0.1A to 0.3A load
Ripple voltage: 100 mV P-P Max
SLOPE COMPENSATION
A fraction of the oscillator ramp can be resistively summed with the current sense signal to provide slope
compensation for converters requiring duty cycles over 50%.
V
REF
8
0.1
mF
R
T
/ C
T
UC1842/3
I
SENSE
3
C
4
C
T
R1
R2
I
SENSE
R
T
R
SENSE
8
TI [ TEXAS INSTRUMENTS ]
