NE5560 Philipss, NE5560 Datasheet - Page 10

• Manufacturer Part Number: NE5560
• Description: Switched-mode power supply control circuit
• Manufacturer: Philipss

Philips Semiconductors
1994 Aug 31
Switched-mode power supply control circuit
Figure 11. Transfer Curve of Pulse-Width Modulator
100
90
80
70
60
50
40
30
20
10
0
(%)
1
Duty Cycle vs Input Voltage
2
3
V
8
4
O
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
/V
7
6
5
4
3
2
1
(+)
REF
V
REF
R
(%)
5
10
S
R
(3.72V)
1
4
3
20
a. Duty Cycle — — % Regulation
6
–
+
V
b. Pulse-Width Modulation
4,5,6 (V)
30
SL00370
3.72V
3
40
Figure 10.
+
ERROR
AMP
–
50
10
PWM
60
Extra PWM Input (Pin 5)
The PWM has an additional inverting input: Pin 5. It allows for
attacking the duty cycle via the PWM circuit, independently from the
feedback and the
SMPS must have a real constant-current behavior, possibly with a
fold-back characteristic. However, the realization of this feature must
be done with additional external components. When not used, Pin 5
should be tied to Pin 6.
(–)
4
70
OUT
80
(–) O.C.
5
90
R
R
R
R
R
R
MAX
S
S
S
f
f
f
(–)
information. This is necessary when the
START/
STOP
6
20
100
500
RESET
NE/SE5560
Product specification
SL00369