NE5560 Philipss, NE5560 Datasheet - Page 14

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

Philips Semiconductors
that it does not saturate, even under transient conditions, where the
max. inductance is determined by
the transformer. The function of ~1/V
Pin 16 of the NE5560.
Figure 20 shows the electrical realization. When the voltage at Pin
16 exceeds the stabilized voltage V
charging current for the timing capacitor on Pin 8.
The operating frequency is not affected, because the upper trip level
for sawtooth increases also. Note that the
remains constant because it is set via V
effect on
these duty cycles have halved. The graph for =f(V
Figure 22.
NOTE:
V
APPLICATIONS
NE/SE5560 Push-Pull Regulator
This application describes the use of the Philips Semiconductors
NE/SE5560 adapted to function as a push-pull switched mode
regulator, as shown in Figures 23 and 24.
Input voltage range is +12V to +18V for a nominal output of +30V
and -30V at a maximum load current of 1A with an average
efficiency of 81%.
Features include feed-forward input compensation, cycle-to-cycle
drive current protection and other voltage sensing, line (to positive
output) regulation <1% for an input range of +13V to +18V and load
regulation to positive output of <3% for I
The main pulse-width modulator operates to 48kHz with power
switching at 24kHz.
1994 Aug 31
MAX
16
Switched-mode power supply control circuit
must be less than Pin 1 voltage.
~1/V
ON
1
IN
MAX
will allow for a considerable reduction or simplification of
T
1
and the normal operating duty cycle . For V
Figure 19. Output Stage Inhibit
2
ON
(50)
T
MAX
Z
(Pin 2), it will increase the
IN
2
Z
can be realized by using
V
. Figure 21 visualizes the
L
IN
(+) of 0.1 to 1A.
MAX
max. A regulation of
ON
voltage on Pin 6
3
16
T
) is given in
3
16
SL00378
=2 V
Z
,
14
C
FEED-FORWARD
SS
V
16
MAX 1
INPUT
Figure 20. External Maximum Control
R
R
100
Figure 22. Feed-Forward Regulation
2
1
90
80
70
60
50
40
30
20
10
Figure 21. Feed-Forward Circuitry
WORKING
T
LEVEL
16
1
2
6
1.5
MAX
V
Z
MAX 2
2
DO NOT EXCEED V
7
R
NE/SE5560
T
T
Product specification
2.5
LEVEL
MAX
V 16
V Z
CC
8
SL00379
C
SL00381
SL00380
2XV
T
Z