Adjustable Micro Power Voltage Regulator
www.fairchildsemi.com
LP2951
Adjustable Micro Power Voltage Regulator
Features
Description
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The LP2951 is an adjustable micro power voltage regulator
suitable for use in battery-powered systems. This regulator
has various functions such as alarm which warns of a low
output voltage, often due to falling batteries on the input, the
external shutdown which enables the regulator to be
switched on and off, current and temperature limiting.
Low Quiescent Current
Low Dropout Voltage
Low Temperature Coefficient
Tight Line and Load Regulation
Guaranteed 100mA Output Current
Internal Short Current & Thermal Limit
Error Signals of Output Dropout (8 pin Versions only)
External Shut Down ( 8-Pin Versions Only)
8-SOP
1
Internal Block Diagram
[3]
Rev. 1.0.3
©2010 Fairchild Semiconductor Corporation
LP2951
Absolute Maximum Ratings
Parameter
2
Symbol
Value
Unit
Input Supply Voltage
VIN
-0.3 ~ +30
V
Power Dissipation
PD
Internally Limited
W
Thermal Resistance Junction-Air
RθJA
127.5
°C/W
Storage Temperature Range
TSTG
-65 ~ +150
°C
Operating Junction Temperature Range
TOPR
-40 ~ +125
°C
LP2951
Electrical Characteristics
(Refer to the test circuit, Ta = 25°C, unless otherwise specified, )
Parameter
Symbol
Conditions
Min.
Typ. Max.
Unit
ALL VOLTAGE OPTIONS
Output Voltage Temperature Coefficient
ΔV/ΔT
(Note1)
-
50
-
ppm/°C
Line Regulation (Note2)
ΔV
(Vo + 1)V ≤ VIN ≤ 28V
IL = 50mA
-
-
0.4
%
Load Regulation (Note2)
ΔV
100uA ≤ IL ≤ 100mA
-
-
0.3
%
Dropout Voltage
VD
IL = 100uA
-
-
150
mV
IL = 100mA
-
-
600
mV
Ground Current
IG
IL = 100uA
-
-
140
uA
Current Limit
ICL
IL = 100mA
VO = 0V
-
-
7
mA
110
165
220
mA
8-PIN VERSIONS ONLY
VREF
VIN = (Vo + 1)V, IL = 100uA
1.235 1.26 1.285
V
VREF
(Note3)
1.225 1.26 1.295
V
Output Low Voltage
VOL
VIN = (Vo - 0.5)V, IOL =400uA
High Threshold Voltage
VTH
Low Threshold Voltage
Reference Voltage
ERROR COMPARATOR
-
150
400
mV
(Note4)
25
60
-
mV
VTL
(Note4)
-
75
140
mV
VHYS
(Note4)
-
15
-
mV
Shutdown Threshold Range
VSD
(Note5)
0.6
1.3
2.0
V
Shutdown Input Current
ISD
VSD = 2.4V
-
30
100
uA
VSD = 28V
-
450
750
uA
Hysteresis
SHUTDOWN INPUT
Note :
1. Output or reference voltage temperature coefficient is defined as the worst case voltage change divided by the total
temperature range.
2. Regulation is measured at constant junction temperature , using pulse testing with a low duty cycle.
3. Vref ≤ Vout ≤ (Vin - 1V), 2.5V ≤ Vin ≤ 28V, 100uA ≤ IL ≤ 100mA, TA ≤ TAMAX .
4. Threshold and hysteresis are expressed in terms of voltage differential at the Feedback terminal below the normal
reference . To express these thresholds in terms of output voltage change , multiply by the error amplifier gain
= VO / VREF = (R1 + R2) / R2 .
5. Vshutdown ≤ 0.6 V , VOUT =ON , Vshutdown ≥ 2.0 V, VOUT = OFF.
3
LP2951
Typical Performance Characteristics
6
2.0
OUTPUT VOLTAGE(V)
GROUND CURRENT(mA)
5
5V OUTPUT
1.6
1.2
0.8
0.4
RL=50Ω
3
2
1
0
0.1
1
10
100
0
1
2
4
5
6
Figure 2. Dropout Characteristics
Figure 1. Quiescent Current
250
120
RL=50Ω
5V OUTPUT
100
200
RL=50K
INPUT CURRENT(mA)
INPUT CURRENT(uA)
3
INP UT VO L T AG E (V)
LOAD CURRENT(mA)
150
100
RL=∞
50
80
60
40
20
0
0
0
2
4
6
8
10
0
2
4
Figure 3. Input Current
8
10
Figure 4. Input Current
5.06
20 0
5V OUTPUT
SHORT CIRCUIT CURRENT(mA)
5.04
6
INPUT VO LT AG E(V )
INPUT VOLTAGE(V)
OUTPUT VOLTAGE(V)
RL=50KΩ
4
5.02
5.00
4.98
4.96
18 0
16 0
14 0
12 0
4.94
-50
-25
0
25
50
75
100
o
TEMPERATURE( C)
Figure 5. Output Voltage vs. Temperature
4
125
10 0
-5 0
-25
0
25
50
75
T E M P E R A T UR E ( o C )
Figure 6. Short Circuit Current
1 00
12 5
LP2951
Typical Performance Characteristics (Continued)
TYPICAL PERFORMANCE CHARACTERISTICS (Continued )
Fig. 8 Dropout
Voltage
Fig. 7 Dropout
Voltage
600
500
IL = 100mA
DROPOUT VOLTAGE(mV)
DROPOUT VOLTAGE(V)
500
400
300
200
0
-50
-25
0
25
50
75
o
TEMPERATURE( C)
Figure 7. Dropout Voltage
100
300
200
o
TJ = 25 C
100
IL = 100μ A
100
400
125
0
0.1
1
10
100
OUTPUT CURRENT(mA)
Figure 8. Dropout Voltage
5
LP2951
Typical Application
VIN
8
VIN
ERROR
SHUTDOWN
5 ERROR V
1
OUT
KA78RLOOD
LP2951
3
SD
GND
4
VOUT
R1
FB
Co
1μF
7
VREF
R2
V O = VREF (1+ R1/ R2)+IFB R1
CO is required between the output and ground for stability at output voltages of 5V or more. since IFB is controlled to less
than 40nA, the error associated with this term is negligible in most applications.
At lower output voltage, more capacitance is required. without this capacitance the part will oscillate.
6
LP2951
Mechanical Dimension
Package
Dimensions in millimeters
8-SOP
MIN
#5
6.00 ±0.30
0.236 ±0.012
8°
0~
+0.10
0.15 -0.05
+0.004
0.006 -0.002
MAX0.10
MAX0.004
1.80
MAX
0.071
3.95 ±0.20
0.156 ±0.008
5.72
0.225
0.41 ±0.10
0.016 ±0.004
#4
1.27
0.050
#8
5.13
MAX
0.202
#1
4.92 ±0.20
0.194 ±0.008
(
0.56
)
0.022
1.55 ±0.20
0.061 ±0.008
0.1~0.25
0.004~0.001
0.50 ±0.20
0.020 ±0.008
7
LP2951
Ordering Information
Product Number
Package
Operationg Temperature
LP2951CM
8-SOP
-40 ~ +125°C
DISCLAIMER
FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY
PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY
LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER
DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.
LIFE SUPPORT POLICY
FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES
OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR
CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body,
or (b) support or sustain life, and (c) whose failure to
perform when properly used in accordance with
instructions for use provided in the labeling, can be
reasonably expected to result in a significant injury of the
user.
2. A critical component in any component of a life support
device or system whose failure to perform can be
reasonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
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© 2010 Fairchild Semiconductor Corporation
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