C
U R R E N T
-M
O D E
PWM C
O N T R O L L E R
SG1844/SG1845 Series
P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7
Copyright 2000
Rev. 1.4 4/00
4
P
R O D U C T I O N
D
A T A
S
H E E T
E L E C T R I C A L C H A R A C T E R I S T I C S
(Cont'd.)
Under-Voltage Lockout Section
Start Threshold
Parameter
Symbol
Test Conditions
1844
1845
1844
1845
Min. Operation Voltage After Turn-On
PWM Section
Maximum Duty Cycle
Minimum Duty Cycle
Power Consumption Section
Start-Up Current
Operating Supply Current
V
CC
Zener Voltage
V
FB
= V
ISENSE
= 0V
I
CC
= 25mA
Notes: 4. These parameters, although guaranteed, are not 100% tested in
production.
5. Parameter measured at trip point of latch with V
VFB
= 0.
SG3844/45
Units
Min. Typ. Max. Min. Typ. Max. Min. Typ. Max.
SG2844/45
15
7.8
9
7.0
16
8.4
10
7.6
17
9.0
11
8.3
15
7.8
9
7.0
16
8.4
10
7.6
17
9.0
11
8.2
14.5
7.8
8.5
7.0
16
8.4
10
7.6
17.5
9.0
11.5
8.2
V
V
V
V
SG1844/45
46
48
50
0
46
48
50
0
46
48
50
0
%
%
0.5
11
34
1
0.5
11
34
V
COMP
V
ISENSE
1
0.5
11
34
1
mA
mA
V
17
17
17
6. Gain defined as: A =
; 0
≤
V
ISENSE
≤
0.8V.
7. Adjust V
above the start threshold before setting at 15V.
8. Output frequency equals one half of oscillator frequency.
Output Low Level
I
SINK
= 20mA
I
SINK
= 200mA
I
SOURCE
= 20mA
I
SOURCE
= 200mA
T
J
= 25°C, C
L
= 1nF
T
J
= 25°C, C
L
= 1nF
Output High Level
Rise Time (Note 4)
Fall Time (Note 4)
Current Sense Section
Gain (Notes 5 & 6)
Maximum Input Signal (Note 5)
Power Supply Rejection Ratio (Note 5)
Input Bias Current
Delay to Output (Note 4)
Output Section
V
COMP
= 5V
12
≤
V
CC
≤
25V
PSRR
2.85
0.9
3
1
3.15 2.85
1.1
3
1
3.15 2.85
1.1
3
1
3.15
1.1
V/V
V
dB
μA
ns
0.9
0.9
70
-2
150
70
-2
150
70
-2
150
-10
300
-10
300
-10
300
0.1
1.5
13.5
13.5
50
50
0.4
2.2
0.1
1.5
13.5
13.5
50
50
0.4
2.2
0.1
1.5
13.5
13.5
50
50
0.4
2.2
V
V
V
V
ns
ns
13
12
13
12
13
12
150
150
150
150
150
150