SG2525AN Просмотр технического описания (PDF) - Microsemi Corporation
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SG2525AN Datasheet PDF : 13 Pages
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Regulating Pulse Width Modulator
Shutdown Options
1. Use an external transistor or open-collector comparator to pull down on the Comp terminal. This sets the
PWM latch turning off both outputs. If the shutdown signal is momentary, pulse-by-pulse protection can be
accomplished as the PWM latch resets with each clock pulse.
2. The same results can be accomplished by pulling down on the Soft-Start terminal with the difference that on
this pin, shutdown does not affect the amplifier compensation network but must discharge any Soft-Start
capacitor.
3. Apply a positive-going signal to the Shutdown terminal. This provides most rapid shutdown of the outputs
but will not immediately set the PWM latch if there is a Soft-Start capacitor. This capacitor discharges but
with a current of approximately twice the charging current.
4. The shutdown terminal can be used to set the PWM latch on a pulse-by-pulse basis if there is no external
capacitance on Soft-Start terminal. Slow turn-on may still be accomplished by applying an external
capacitor, blocking diode, and charging resistor to the comp terminal. (See SG1524 Application Note).
VREF
CLOCK
16
0.1µF
3 kΩ
4
SYNC
PWM
ADJ
3
RT
10 kΩ
3.6 kΩ
0.009µF
1.5
kΩ
CT
0.1µF
RAMP
6
DEADTIME
7
100 Ω
5
0.001µF
COMP
_
V/I METER
+
1 = VOS
2 = I(+)
3 = I(-)
1
2
3
1
2
3
10 kΩ
9
0.01µF
1
2
1
3
1
2
2
3
REFERENCE
REGULATOR
FLIP/
FLOP
O
S
A
C
I
L
L
A
T
O
R
B
PWM
E/A
D.U.T
50 µA
5k
15
+VIN
0.1µF
13
VC
0.1µF
OUT A
11
1k, 1W
(2)
14
OUT B
12
GND
SOFTSTART
8
+
5µF
SHUTDOWN
5k
10
2k
VREF
2k
Figure 9 · SG1525A/1527A Lab Test Fixture
10
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