NE5562D Philipss, NE5562D Datasheet - Page 15

• Manufacturer Part Number: NE5562D
• Description: Switched-mode power supply control circuit
• Manufacturer: Philipss

Philips Semiconductors
2. Slow-start if remote ON/OFF is actuated, if OC2 threshold trips,
3. Note that Pin 8 is monitored by the loop fault comparator. When
Referring to the graph in Figure 25, the designer may choose a
divider ratio which, when referenced to V
duty cycle limit control. For example, a 50% limit results in a ratio of
0.48. Setting R
solving for R
Example:
1994 Aug 31
A duty cycle limit of 50% is required for a forward converter.
Switched-mode power supply control circuit
demagnetization/overvoltage is sensed, or low supply voltage to
the internal regulator is sensed (VS 8.45V).
the regulated supply feedback drops below this threshold level
(0.955V), the duty cycle is clamped by two diodes in series with
a 2k load across Pin 5 to ground. This implies a minimum duty
cycle condition as long as the low output level remains.
ERROR
AMP IN
1
, the proper limit is obtained.
2
at a nominal value between 10 and 20k and
8
FAULT
COMP
V
LOOP
Z
PWM COMP
Z
, 7.5V, provides an easy
START
SLOW
MAX TO
0.955V
CAP
DELTA
C
Figure 24. Duty Cycle Limit Control
SS
2k
R
R
1
2
5
50
START/STOP
LATCH
15
FROM
STOP
‘A’
R
0.48R
2
R
= 10k , find R
R
2
+
1
= 0.48 (R
1
R
= 10.8k
R
= R
1
2
R
2
10k
2
– 0.48R
R
1
2
0.48
(1
+ R
1
(0.52)
0.48
0.48
0.9V
2
2
)
0.48)
START
SLOW
COMP
36 A
0.9V
N BIAS
START
NE/SE5562
SLOW
COMP
OUT
Product specification
9k
V
Z
1.5V
SL00411