LP2950/2951
Micrel
3
February 1999
3-35
LP2950/2951
100mA Low-Dropout Voltage Regulator
General Description
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 (75
A
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.
Available in a 3-Pin TO-92 package, the LP2950 is pin-
compatible with the older 5V regulators. Additional system
functions, such as programmable output voltage and logic-
controlled shutdown, are available in the 8-pin DIP and 8-pin
SOIC versions of the LP2951.
Features
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 1
F for stability
Current and thermal limiting
LP2951 Versions Only
Error flag warns of output dropout
Logic-controlled electronic shutdown
Output programmable from 1.24 to 29V
Block Diagram and Pin Configurations
LP2950 and LP2951 Block Diagram
(Pin Numbers Refer to LP2951)
1
2
3
4
8
7
6
5
OUTPUT
SENSE
SHUTDOWN
GROUND
ERROR
5V TAP
FEEDBACK
INPUT
GROUND
OUTPUT
INPUT
TO-92 Plastic Package Bottom View
(BZ)
DIP and SO Packages
(BN and BM)
Applications
Automotive Electronics
Voltage Reference
Avionics
3 2
1
See MIC2950 for a part with 1) higher output (150 mA), 2) transient protection (60V), and 3) reverse input protection to 20V)
5V TAP
6
SENSE
2
GROUND
4
ERROR
5
TO CMOS
OR TTL
330
k
+
1.5 F
60
k
182
k
OUTPUT
INPUT
FEEDBACK
1
8
7
5V
150 mA
MAX.
+
+
ERROR
AMPLIFIER
ERROR
DETECTION
COMPARATOR
+
1.23 V
REF.
+
60 mV
SHUT-
DOWN
3
FROM
CMOS
OR TTL
+
UNREGULATED DC
LP2950/2951
Micrel
3-36
February 1999
Additional features available with the LP2951 also include an
error flag output that warns of a low output voltage, which is
often due to failing batteries on the input. This may also be
used as a power-on reset. A logic-compatible shutdown input
is also available which enables the regulator to be switched on
and off. This part may also be pin-strapped for a 5V output,
or programmed from 1.24V to 29V with the use of two external
resistors.
The LP2950 is available as either an -02 or -03 version. The
-02 and -03 versions are guaranteed for junction temperatures
from 40
C to +125
C; the -02 version has a tighter output and
reference voltage specification range over temperature. The
LP2951 is available as an -02 or -03 version.
The LP2950 and LP2951 have a tight initial tolerance (0.5%
typical), a very low output voltage temperature coefficient
which allows use as a low-power voltage reference, and
extremely good load and line regulation (0.05% typical). This
greatly reduces the error in the overall circuit, and is the result
of careful design techniques and process control.
Absolute Maximum Ratings
If Military/Aerospace specified devices are required, contact your local
Micrel representative/distributor for availability and specifications.
Power dissipation
Internally Limited
Lead Temperature (Soldering, 5 seconds)
260
C
Storage Temperature Range
65
C to +150
C
Operating Junction Temperature Range (Note 8)
LP2950, LP2951
40
C to +125
C
Input Supply Voltage
0.3V to +30V
Feedback Input Voltage (Notes 9 and 10)
1.5V to +30V
Shutdown Input Voltage (Note 9)
0.3V to +30V
Error Comparator Output Voltage (Note 9)
0.3V to +30V
ESD Rating is to be determined.
Ordering Information
Part Number
Voltage
Temperature Range*
Package
Accuracy
LP2950-02BZ
5.0V
40
C to +125
C
3-Pin TO-92 plastic
0.5%
LP2950-03BZ
5.0V
40
C to +125
C
3-Pin TO-92 plastic
1.0%
LP2951-02BM
5.0V
40
C to +125
C
8-Pin SOIC
0.5%
LP2951-03BM
5.0V
40
C to +125
C
8-Pin SOIC
1.0%
LP2951-02BN
5.0V
40
C to +125
C
8-Pin Plastic DIP
0.5%
LP2951-03BN
5.0V
40
C to +125
C
8-Pin Plastic DIP
1.0%
LP2951-4.8BM
4.85V
40
C to +125
C
8-Pin SOIC
1.0%
* Junction temperatures
LP2950/2951
Micrel
3
February 1999
3-37
Electrical Characteristics
Note 1 T
A
= 25
C except as noted.
Parameter
Condition
Min
Typ
Max
Units
Output Voltage
LP295x-02 (
0.5%)
4.975
5.000
5.025
V
T
J
= 25
C
LP295x-03 (
1%)
4.950
5.000
5.050
V
LP2951-4.8 (
1%)
4.802
4.850
4.899
V
Output Voltage
LP295x-02 (
0.5%)
4.950
5.050
V
25
C
T
J
+85
C
LP295x-03 (
1%)
4.925
5.075
V
LP2951-4.8 (
1%)
4.777
4.872
V
Output Voltage
LP295x-02 (
0.5%), 40
C to +125
C
4.940
5.060
V
Over Full Temperature Range
LP295x-03 (
1%), 40
C to +125
C
4.900
5.100
V
LP2951-4.8 (
1%), 40
C to +125
C
4.753
4.947
V
Output Voltage
LP295x-02 (
0.5%), 100
A
I
L
100mA, T
J
T
J(max)
4.930
5.070
V
Over Load Variation
LP295x-03 (
1%), 100
A
I
L
100mA, T
J
T
J(max)
4.880
5.120
V
LP2951-4.8 (
1%), 100
A
I
L
100mA, T
J
T
J(max)
4.733
4.967
V
Output Voltage
LP295x-02 (
0.5%), Note 12
20
100
ppm/
C
Temperature Coefficient
LP295x-03 (
1%), Note 12
50
150
ppm/
C
LP2951-4.8 (
1%), Note 12
50
150
ppm/
C
Line Regulation
LP295x-02 (
0.5%), Notes 14, 15
0.03
0.10
%
0.20
%
LP295x-03 (
1%), Notes 14, 15
0.04
0.20
%
0.40
%
LP2951-4.8 (
1%), Notes 14, 15
0.04
0.20
%
0.40
%
Load Regulation
LP295x-02 (
0.5%), Note 14, 100
A
I
L
100mA
0.04
0.10
%
0.20
%
LP295x-03 (
1%), Note 14, 100
A
I
L
100mA
0.10
0.20
%
0.30
%
LP2951-4.8 (
1%), Note 14, 100
A
I
L
100mA
0.10
0.20
%
0.30
%
Dropout Voltage
Note 5, I
L
= 100
A
50
80
mV
150
mV
Note 5, I
L
= 100mA
380
450
mV
600
mV
Ground Current
I
L
= 100
A
100
150
A
200
A
I
L
= 100mA
8
12
mA
14
mA
Dropout Current
V
IN
= 4.5V, I
L
= 100
A
180
250
A
310
A
LP2950/2951
Micrel
3-38
February 1999
Parameter
Condition
Min
Typ
Max
Units
Current Limit
V
OUT
= 0V
160
200
mA
220
mA
Thermal Regulation
Note 13
0.05
0.20
%/W
Output Noise
10Hz to 100kHz, C
L
= 1
F
430
V
RMS
10Hz to 100kHz, C
L
= 200
F
160
V
RMS
10Hz to 100kHz, C
L
= 3.3
F,
100
V
RMS
0.01
F bypass Feedback to Output
Reference Voltage
LP295x-02 (
0.5%)
1.220
1.235
1.250
V
1.200
1.260
V
LP295x-03 (
1%)
1.210
1.235
1.260
V
1.200
1.270
V
LP2951-4.8 (
1%)
1.210
1.235
1.260
V
1.200
1.270
V
Reference Voltage
LP295x-02 (
0.5%), Note 7
1.190
1.270
V
LP295x-03 (
1%), Note 7
1.185
1.285
V
LP2951-4.8 (
1%), Note 7
1.185
1.285
V
Feedback Bias Current
20
40
nA
60
nA
Reference Voltage
LP295x-02 (
0.5%), Note 12
20
ppm/
C
LP295x-03 (
1%), Note 12
50
ppm/
C
LP2951-4.8 (
1%), Note 12
50
ppm/
C
Feedback Bias Current
0.1
nA/
C
Temperature Coefficient
Output Leakage Current
V
OH
= 30V
0.01
1.00
A
2.00
A
Output Low Voltage (Flag)
V
IN
= 4.5V, I
OL
= 200
A
150
250
mV
400
mV
Upper Threshold Voltage
Note 6
40
60
mV
25
mV
Lower Threshold Voltage
Note 6
75
95
mV
140
mV
Hysteresis
Note 6
15
mV
Input Logic Voltage
LP295x-02 (
0.5%)
1.3
V
Low
0.7
V
High
2.0
V
LP295x-03 (
1%)
1.3
V
Low
0.7
V
High
2.0
V
LP2951-4.8 (
1%)
1.3
V
Low
0.7
V
High
2.0
V
LP2950/2951
Micrel
3
February 1999
3-39
Parameter
Condition
Min
Typ
Max
Units
Shutdown Input Current
V
SHUTDOWN
= 2.4V
30
50
A
100
A
V
SHUTDOWN
= 30V
450
600
A
750
A
Regulator Output Current
Note 11
3
10
A
in Shutdown
20
A
Note 1:
Boldface limits apply at temperature extremes.
Note 2:
Unless otherwise specified all limits guaranteed for T
J
= 25
C, V
IN
= 6V, I
L
= 100
A and C
L
= 1
F. Additional conditions for the 8-pin versions
are Feedback tied to 5V Tap and Output tied to Output Sense (V
OUT
= 5V) and V
SHUTDOWN
0.8V.
Note 3:
Guaranteed and 100% production tested.
Note 4:
Guaranteed but not 100% production tested. These limits are not used to calculate outgoing AQL levels.
Note 5:
Dropout voltage is defined as the input to output differential at which the output voltage drops 100mV below its nominal value measured at 1V
differential. At very low values of programmed output voltage, the minimum input supply voltage of 2V (2.3V over temperature) must be taken
into account.
Note 6:
Comparator thresholds are expressed in terms of a voltage differential at the Feedback terminal below the nominal reference voltage
measured at 6V input. To express these thresholds in terms of output voltage change, multiply by the error amplifier gain = V
OUT
/V
REF
=
(R1 + R2)/R2. For example, at a programmed output voltage of 5V, the Error output is guaranteed to go low when the output drops by
95mV x 5V/1.235V = 384mV. Thresholds remain constant as a percent of V
OUT
as V
OUT
is varied, with the dropout warning occurring at
typically 5% below nominal, 7.5% guaranteed.
Note 7:
V
REF
V
OUT
(V
IN
1 V), 2.3V
V
IN
30V, 100
A < I
L
100mA, T
J
T
JMAX
.
Note 8:
The junction-to-ambient thermal resistance of the TO-92 package is 180
C/W with 0.4" leads and 160
C/W with 0.25" leads to a PC board.
The thermal resistance of the 8-pin DIP package is 105
C/W junction-to-ambient when soldered directly to a PC board. Junction-to-ambient
thermal resistance for the SOIC (M) package is 160
C/W.
Note 9:
May exceed input supply voltage.
Note 10: When used in dual-supply systems where the output terminal sees loads returned to a negative supply, the output voltage should be diode-
clamped to ground.
Note 11: V
SHUTDOWN
2V, V
IN
30 V, V
OUT
= 0, with Feedback pin tied to 5V Tap.
Note 12: Output or reference voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
Note 13: Thermal regulation is defined as the change in output voltage at a time T after a change in power dissipation is applied, excluding load or line
regulation effects. Specifications are for a 50mA load pulse at V
IN
= 30V (1.25W pulse) for t = 10ms.
Note 14: Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to heating
effects are covered in the specification for thermal regulation.
Note 15: Line regulation for the LP2951 is tested at 150
C for I
L
= 1mA. For I
L
= 100
A and T
J
= 125
C, line regulation is guaranteed by design to
0.2%. See Typical Performance Characteristics for line regulation versus temperature and load current.
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