ip3524bdw Semelab Group, ip3524bdw Datasheet - Page 5

• Manufacturer Part Number: ip3524bdw
• Description: Regulating Pulse Width Modulators
• Manufacturer: Semelab Group

LAB
modulation voltage regulator control circuit. The
regulator operates at a frequency that is programmed
by one timing resistor (R
(C
which is fed to the comparator providing linear control of
the output pulse width by the error amplifier.
serves as a reference as well as powering the IP1524’s
internal control circuitry and is also useful in supplying
external support functions. This reference voltage is
lowered externally by a resistor divider to provide a
reference within the common-mode range of the error
amplifier or an external reference may be used. The
power supply output is sensed by a second resistor
divider network to generate a feedback signal to the
error amplifier. The amplifier output voltage is then
compared to the linear voltage ramp at C
resulting modulated pulse out of the high-gain
comparator is then steered to the appropriate output
pass transistor (Q
which is synchronously toggled by the oscillator output.
the IP1524 are connected in parallel for effective 0-90% duty cycle
modulation. The use of an output inductor requires an R-C phase
compensation network for loop stability.
Semelab plc.
SEME
The IP1524 is a fixed-frequency pulse-width
The IP1524 contains an on-board 5V regulator that
In this conventional single-ended regulator circuit, the two outputs of
T
). R
R E T U R N
T
+ 28 V
establishes a constant charging current for C
0. 02 F
0. 1 F
5 k
5 k
3 k
5 k
5 k
1
Telephone [phone]. Telex: 341927. Fax [phone].
I NV .
N. I.
V
R
C
O S C .
S H . D O W N
RE F
T
T
or Q
G N D
V
2
I N
) by the pulse-steering flip-flop,
C O M P .
T
) and one timing capacitor
C +
C
C -
E
C
E
L
A
L
A
B
B
5 0 k
0.0 01 F
1 5 0
6 8
2 k
APPLICATIONS INFORMATION
1 N3 8 80
0.9 mH
0 . 1
T
. The
5 0 0 F
+ 5 V
1 A
G N D
T
,
R E T U R N
regulating converter. Note that the oscillator must be set at twice the
desired output frequency as the IP1524’s internal flip-flop divides the
frequency by 2 as it switches the PWM signal from one output to the
other. Current limiting is done in the primary so that the pulse width will
be reduced should transformer saturation occur.
+ 28 V
Push-pull outputs are used in this transformer-coupled DC-DC
pulse to assure both outputs are never on
simultaneously during the transition times.
value of C
configuration in which their frequency is half that of the
base oscillator, or paralleled for single-ended
applications in which the frequency is equal to that of
the oscillator. The output of the error amplifier shares a
common input to the comparator with the current
limiting and shutdown circuitry and can be overridden
by signals from either of these inputs.
may be employed to control the gain of, or to
compensate, the error amplifier, or to provide additional
control to the regulator.
The width of the blanking pulse is controlled by the
The outputs may be applied in a push-pull
This common point is also available externally and
The oscillator output pulse also serves as a blanking
0. 01 F
0.1 F
5 k
5 k
2 k
5 k
5 k
T
.
I N V .
N. I.
V
R
C
O S C .
S H . D O W N
RE F
T
T
G N D
V
I N
C O M P .
C +
C
C -
E
C
E
L
L
A
A
B
B
1 k
1 W
2 0 k
0.001 F
IP1524 SERIES
1 k
1 W
1 k
1 k
0 . 1
1 0 0 F
2 0
2 0
T
T
5
T
5
T
Prelim. 3/95
1 m H
1 0 0 F
5 V
5 A