LP2950/2951
Micrel
LP2950/2951
100mA Low-Dropout Voltage Regulator
General Description
Features
The LP2950 and LP2951 are micropower voltage regulators
with very low dropout voltage (typically 40mV at light loads
and 380mV at 100mA), and very low quiescent current (75µA
typical). The quiescent current of the LP2950/LP2951
increases only slightly in dropout, thus prolonging battery life.
This feature, among others, makes the LP2950 and LP2951
ideally suited for use in battery-powered systems.
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Available in a 3-Pin TO-92 package, the LP2950 is pincompatible with the older 5V regulators. Additional system
functions, such as programmable output voltage and logiccontrolled shutdown, are available in the 8-pin DIP and 8-pin
SOIC versions of the LP2951.
Applications
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Automotive Electronics
Voltage Reference
Avionics
High accuracy 5V, guaranteed 100 mA output
Extremely low quiescent current
Low-dropout voltage
Extremely tight load and line regulation
Very low temperature coefficient
Use as regulator or reference
Needs only 1µF for stability
Current and thermal limiting
LP2951 Versions Only
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Error flag warns of output dropout
Logic-controlled electronic shutdown
Output programmable from 1.24 to 29V
Block Diagram and Pin Configurations
UNREGULATED DC
7
+
8
FEEDBACK
INPUT
5V
150 mA
MAX.
1
OUTPUT
2
SENSE
+
3
FROM
CMOS
OR TTL
SHUTDOWN
–
182
kΩ
ERROR
AMPLIFIER
60 mV
+
1.23 V
REF.
+
5V TAP
60
kΩ
+
–
6
5
+
1.5 µF
TO CMOS
OR TTL
ERROR
ERROR
DETECTION
COMPARATOR
330
kΩ
4
GROUND
LP2950 and LP2951 Block Diagram
(Pin Numbers Refer to LP2951)
1
2
7
SHUTDOWN
3
6
4
5
OUTPUT
1
OUTPUT
8
SENSE
3 2
INPUT
GROUND
GROUND
INPUT
FEEDBACK
5V TAP
ERROR
DIP and SO Packages
(BN and BM)
TO-92 Plastic Package Bottom View
(BZ)
See MIC2950 for a part with 1) higher output (150 mA), 2) transient protection (60V), and 3) reverse input protection to –20V)
February 1999
3-35
3