P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7
SG1842/SG1843 Series
C
U R R E N T - M O D E P W M C O N T R O L L E R
P R O D U C T I O N D A T A S H E E T
TYPICAL APPLICATION CIRCUITS (continued)
TI
USD735
4.7W 1W
220µF
250V
0.01pF
400V
5V
2-5A
4700µF
673-3
10V
56kW
1W
1N3613
AC
INPUT
1N3613
16V
SG1842
10µF
20V
20kW
820pF
T1: Coilcraft E - 4140 - b
Primary - 97 turns
single AWG 24
0.01µF
VFB
VCC
2.5kW
Secondary - 4 turns
4 parallel AWG 22
Control - 9 turns
27W
150kW
COMP
OUT
3 parallel AWG 28
3.6kW
20kW
100pF
VREF
1kW
470pF
CUR
SEN
10kW
0.85W
R / CT
T
GND
0.01µF
.0047µF
ISOLATION
BOUNDARY
FIGURE 25. — OFF-LINE FLYBACK REGULATOR
SPECIFICATIONS
Input line voltage:
Input frequency:
90VAC to 130VAC
* This circuit uses a low-cost feedback scheme in which the DC
voltage developed from the primary-side control winding is
sensed by the SG1842 error amplifier. Load regulation is
therefore dependent on the coupling between secondary
and control windings, and on transformer leakage
inductance.
50 or 60Hz
40KHz 10%
25W maximum
5V +5%
2 to 5A
0.01%/V
Switching frequency:
Output power:
Output voltage:
Output current:
Line regulation:
Load regulation:
Efficiency @ 25 Watts,
VIN = 90VAC:
8%/A*
70%
65%
VIN = 130VAC:
Output short-circuit current: 2.5Amp average
Copyright © 2000
Rev. 1.6 4/00
14
MICROSEMI [ Microsemi ]
