LX2172CM 查看數據表（PDF） - Microsemi Corporation
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LX2172CM Datasheet PDF : 6 Pages
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PRODUCT DATABOOK 1996/1997
LX2172/73
1.25A HIGH-EFFICIENCY 100KHZ SWITCHING REGULATOR
PR E L I M I N A RY D ATA S H E E T
Parameter
SYNC Input Section (LX2172 only)
SYNC Pulse Width
SYNC Input HI
SYNC Input LO
SYNC Input Current HI
SYNC Input Current LO
ENABLE Section (LX2173 only)
Enable Input Threshold
HI Input Current
LO Input Current
ELECTRICAL CHARACTERISTICS
Symbol
Test Conditions
Input = 2V
Input = 0.4V
Input = 2.4V
Input = 0.4V
LX2172 / 2173
Units
Min. Typ. Max.
0.2
2 µsec
2
6
V
0.7
V
100 400 µA
1
5
µA
0.4 1.2 2.4
V
200 µA
100 µA
Pin
Name
Pin #
Pin #
(8-pin Pkgs.) (5-pin TO-220)
FUNCTIONAL PIN DESCRIPTION
Description
GND
1
VC
2
3
Signal ground. Keep separate from power grounds (E and E ).
1
2
1
Output of transconductance error amplifier. An R-C compensation network is connected from
this pin to the ground to stabilize the feedback loop. If this pin is pulled lower than 0.15V, the
IC goes into micropower mode.
FB
3
SYNC
4
2
Error amplifier inverting input. A resistor divider from the output of the converter to this pin sets
its nominal voltage.
LX2172 only. This pin is used to synchronize the device directly with a logic level input pulse.
External synchronization frequency must always be at a higher frequency than the minimum
internal clock. When not used, should be left open.
ENABLE
4
VIN
5
E1
6
VSW
7
E2
8
LX2173 only. This pin is the input to the enable comparator. A voltage under 1.4V will put the
device in micropower mode. Pin must be connected to VIN when not in use.
5
Input supply voltage (3.0V to 25V).
Power return of first transistor (Q1). This pin must be connected to ground.
4
Collector of output transistors. Connect to external inductor or input voltage, depending on circuit
topology.
Grounding this pin sets the current limit point to the maximum value. If pin is left open, the current
limit is set to half its maximum value.
4
Copyright © 1998
Rev. 0.4a 12/04
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