IP1524J-BSS2 데이터 시트보기 (PDF) - Semelab - > TT Electronics plc
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IP1524J-BSS2 Datasheet PDF : 6 Pages
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SEME
LAB
IP1524 SERIES
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 (RT) and one timing capacitor
(CT). RT establishes a constant charging current for CT,
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 CT. The
resulting modulated pulse out of the high-gain
comparator is then steered to the appropriate output
pass transistor (Q1 or Q2) by the pulse-steering flip-flop,
which is synchronously toggled by the oscillator output.
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 CT.
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.
+28V
5kΩ
68Ω
5kΩ
VI N
INV.
CA
150Ω
5kΩ
N.I.
EA
0. 1µF
5kΩ
VRE F
2kΩ
CB
3kΩ
RT
EB
0. 02µF
CT
CL+
0.9mH
+5V
1A
1N3880
5 0 0µF
OSC.
C L-
SH.DOWN
COM P.
GND
0.0 01µF
50k Ω
GND
RETURN
0 . 1Ω
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.
+28V
RETURN
5kΩ
5kΩ
VI N
INV.
CA
5kΩ
N.I.
EA
0.1µF 5 k Ω
VRE F
CB
2kΩ
RT
EB
0. 01µF
CT
CL+
OSC.
C L-
SH.DOWN
COMP.
GND
1kΩ
1W
1kΩ
1W
1kΩ
1kΩ
0 . 0 0 1µF
20k Ω
0 . 1Ω
20
5
T
T
20
5
T
T
1 0 0µF
1mH
1 0 0µF
5V
5A
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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