NE5560 Philipss, NE5560 Datasheet - Page 7

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

Philips Semiconductors
TYPICAL PERFORMANCE CHARACTERISTICS
THEORY OF OPERATION
The following functions are incorporated:
The PWM has two additional inputs:
Pin 6 can be used for a precise setting of
Pin 5 gives a direct access to the modulator, allowing for real
constant-current operation:
1994 Aug 31
– A temperature-compensated reference source.
– An error amplifier with Pin 3 as input. The output is connected
– A sawtooth generator with a TTL-compatible synchronization
– A pulse-width modulator with a duty cycle range from 0 to 95%.
– A gate at the output of the PWM provides a simple dynamic
– A latch that is set by the flyback of the sawtooth and reset by
– Another latch functions as a start-stop circuit; it provides a fast
– A current protection circuit that operates via the start-stop
– A TTL-compatible remote on/off input at Pin 10, also operating
– An inhibit input at Pin 13. The output pulse can be inhibited
– An output gate that is commanded by the latches and the inhibit
Switched-mode power supply control circuit
to Pin 4 so that the gain is adjustable with external resistors.
input (Pins 7, 8, 9).
current limit.
the output pulse of the above mentioned gate prohibits double
pulsing.
switch-off and a slow start.
circuit. This is a combined function with the current limit circuit,
therefore Pin 11 has two trip-on levels; the lower one for
cycle-by-cycle current limiting, the upper one for current
protection by means of switch-off and slow-start.
via the start-stop circuit.
immediately.
circuit.
1000
100
90
80
70
60
50
40
30
20
10
9
8
7
6
5
4
3
2
1
f(kHz)
Typical Frequency Plot vs R
2
2.5
3
R=20k
R=10k
R=40k
C
R=5k
T
3.5
MAX
Figure 5. Typical Performance Characteristics
4
T
and
4.5
CnF)
(Continued)
7
Stabilized Power Supply (Pins 1, 2, 12)
The power supply of the NE5560 is of the well known series
regulation type and provides a stabilized output voltage of typically
8.5V.
This voltage V
setting of
capability is 5mA.
The circuit can be fed directly from a DC voltage source between
10.5V and 18V or can be current-driven via a limiting resistor. In the
latter case, internal pinch-off resistors will limit the maximum supply
voltage: typical 23V for 10mA and max. 30V for 30mA.
The low supply voltage protection is active when V
10.5V and inhibits the output pulse (no hysteresis).
When the supply voltage surpasses the 10.5V level, the IC starts
delivering output pulses via the slow-start function.
– An output transistor of which both the collector (Pin 15) and the
– A power supply that can be either voltage- or current-driven
– A special function is the so-called feed-forward at Pin 16. The
– Loop fault protection circuits assure that the duty cycle is
100
emitter (Pin 14) are externally available. This allows for normal
or inverse output pulses.
(Pins 1 and 12). The internally-generated stabilized output
voltage VZ is connected to Pin 2.
amplitude of the sawtooth generator is modulated in such a way
that the duty cycle becomes inversely proportional to the
voltage on this pin: ~ 1/V16.
reduced to zero or a low value for open- or short-circuited
feedback loops.
90
80
70
60
50
40
30
20
10
MAX
1
Z
and to supply external circuitry. Its max. current
is also present at Pin 2 and can be used for precise
1.5
2
NE/SE5560
Product specification
2.5
(1-12)
V 16
V Z
is below
SL00364