LAB
TOP VIEW
INV. INPUT
1
N. I. INPUT
2
OSC. OUTPUT
3
+C.L. SENSE
4
–C.L. SENSE
5
R
T
6
C
T
7
GROUND
8
16
15
14
13
12
11
10
9
SEME
IP1524 SERIES
V
REF
V
IN
E
B
C
B
C
A
E
A
SHUTDOWN
COMPENSATION
REGULATING
PULSE WIDTH
MODULATORS
FEATURES
•
•
•
•
•
Guaranteed ±2% reference voltage tolerance
Guaranteed ±6% oscillator tolerance
Fully specified temperature performance
Guaranteed 10mV/1000 hours long term stability
Interchangeable with SG1524 series
J Package – 16 Pin Ceramic DIP
N Package – 16 Pin Plastic DIP
D Package – 16 Pin Plastic (150) SOIC
Order Information
Part
Number
IP1524
IP2524
IP3524
J–Pack
16 Pin
N–Pack
16 Pin
D–16
16 Pin
Temp.
Range
-55 to +125°C
-25 to +85°C
0 to +70°C
Note:
To order, add the package identifier to the part number.
eg.
IP1524J
IP3524D–16
ABSOLUTE MAXIMUM RATINGS
(T
case
= 25°C unless otherwise stated)
+V
IN
Input Voltage
Collector Voltage
Output Current
Reference Load Current
Oscillator Charging Current
Shut Down Pin Voltage
Current Limit Sense Common Mode Range
P
D
P
D
T
J
T
STG
T
L
Power Dissipation
Power Dissipation
T
A
= 25°C
Derate @ T
A
> 50°C
T
C
= 25°C
Derate @ T
C
> 25°C
(each transistor)
+40V
+40V
100mA
Internally Limited
5mA
+5.5V
–1.0 to +1.0V
1W
10mW/°C
2W
16mW/°C
See Ordering Information
–65 to +150°C
(soldering, 10 seconds)
+300°C
Prelim. 3/95
Operating Junction Temperature
Storage Temperature Range
Lead Temperature
Semelab plc.
Telephone (01455) 556565. Telex: 341927. Fax (01455) 552612.
LAB
DESCRIPTION
The IP1524 series of PWM switching regulator control circuits contains all the functions required to implement single-
ended or push-pull switching regulators. Included are voltage reference, error amplifer, oscillator, PWM comparator,
output drivers, current limiting and shutdown circuitry.
Although functionally indentical to the SG1524 series, SEMELAB has incorporated several improvements to the IP1524
allowing tighter and more complete specification of electrical performance.
SEME
IP1524 SERIES
BLOCK DIAGRAM
16
V
IN
15
REFERENCE
REGULATOR
+5V TO ALL
INTERNAL CIRCUITRY
OSCILLATOR
OUTPUT
3
12
R
T
C
T
6
C
A
NOR
FLIP
FLOP
11
7
OSCILLATOR
E
A
C
B
13
+5V
COMPARATOR
NOR
INV.
INPUT
N.I.
INPUT
GND
(SUBSTRATE)
SHUTDOWN
1
2
14
ERROR
AMP
+5V
9
E
B
+5V
C.L.
COMPENSATION
4
5
+SENSE
–SENSE
8
10
1kΩ
10kΩ
RECOMMENDED OPERATING CONDITIONS
V
IN
Input Voltage
Collector Voltage
Error Amp Common Mode Range
Output Current
Reference Load Current
Oscillator Charging Current
Oscillator Frequency Range
R
T
C
T
T
AMB
Oscillator Timing Resistor
Oscillator Timing Capacitor
Operating Ambient Temperature Range
IP1524
IP2524
IP3524
(each transistor)
+8 to +40V
0 to +40V
+1.8 to +3.4V
0 to 100mA
0 to 20mA
30µA to 2mA
50Hz to 500kHz
1.8kΩ to 100kΩ
1nF to 0.1µF
–55 to +125°C
-25 to +85°C
0 to +70°C
Semelab plc.
Telephone (01455) 556565. Telex: 341927. Fax (01455) 552612.
Prelim. 3/95
LAB
APPLICATIONS INFORMATION
The IP1524 is a fixed-frequency pulse-width
modulation voltage regulator control circuit. The
regulator operates at a frequency that is programmed
by one timing resistor (R
T
) and one timing capacitor
(C
T
). R
T
establishes a constant charging current for C
T
,
which is fed to the comparator providing linear control of
the output pulse width by the error amplifier.
The IP1524 contains an on-board 5V regulator that
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
T
. The
resulting modulated pulse out of the high-gain
comparator is then steered to the appropriate output
pass transistor (Q
1
or Q
2
) by the pulse-steering flip-flop,
which is synchronously toggled by the oscillator output.
+ 28 V
5k
Ω
5k
Ω
SEME
IP1524 SERIES
The oscillator output pulse also serves as a blanking
pulse to assure both outputs are never on
simultaneously during the transition times.
The width of the blanking pulse is controlled by the
value of C
T
.
The outputs may be applied in a push-pull
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.
This common point is also available externally and
may be employed to control the gain of, or to
compensate, the error amplifier, or to provide additional
control to the regulator.
0.9 mH
68
Ω
V
I N
I NV .
N. I.
5k
Ω
+5V
1A
+ 28 V
5k
Ω
5k
Ω
C
A
E
A
150
Ω
V
I N
INV.
N. I.
1k
Ω
1W
1k
Ω
1W
1mH
5k
Ω
0. 1µF
3k
Ω
0. 02µF
1 N3 8 80
5 0 0µF
2k
Ω
C
A
E
A
1k
Ω
20
T
20
T
5V
5A
5k
Ω
0.1µF
2k
Ω
0. 01µF
5k
Ω
V
RE F
R
T
C
B
E
B
5
T
5
T
1 0 0µF
V
RE F
R
T
C
B
1k
Ω
E
B
C
T
OS C.
SH .DOWN
GND
C
L
+
C
L
-
C
T
OS C.
COM P.
0.0 01µF
50k
Ω
GND
RE TURN
RE TURN
0 . 1
Ω
C
L
+
C
L
-
COMP .
0.001µF
20k
Ω
0 . 1Ω
1 0 0
µ
F
SH .DOWN
GND
In this conventional single-ended regulator circuit, the two outputs of
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.
Push-pull outputs are used in this transformer-coupled DC-DC
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.
Semelab plc.
Telephone (01455) 556565. Telex: 341927. Fax (01455) 552612.
Prelim. 3/95
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