© Semiconductor Components Industries, LLC, 2011
September, 2011 Rev. 25
1Publication Order Number:
LP2950/D
LP2950, LP2951, NCV2951
100 mA, Low Power Low
Dropout Voltage Regulator
The LP2950 and LP2951 are micropower voltage regulators that are
specifically designed to maintain proper regulation with an extremely
low inputtooutput voltage differential. These devices feature a very
low quiescent bias current of 75 mA and are capable of supplying
output currents in excess of 100 mA. Internal current and thermal
limiting protection is provided.
The LP2951 has three additional features. The first is the Error
Output that can be used to signal external circuitry of an out of
regulation condition, or as a microprocessor poweron reset. The
second feature allows the output voltage to be preset to 5.0 V, 3.3 V or
3.0 V output (depending on the version) or programmed from 1.25 V
to 29 V. It consists of a pinned out resistor divider along with direct
access to the Error Amplifier feedback input. The third feature is a
Shutdown input that allows a logic level signal to turnoff or turnon
the regulator output.
Due to the low inputtooutput voltage differential and bias current
specifications, these devices are ideally suited for battery powered
computer, consumer, and industrial equipment where an extension of
useful battery life is desirable. The LP2950 is available in the three
pin case 29 and DPAK packages, and the LP2951 is available in the
eight pin dualinline, SOIC8 and Micro8 surface mount packages.
The ‘A’ suffix devices feature an initial output voltage tolerance
±0.5%.
Features
Low Quiescent Bias Current of 75 mA
Low InputtoOutput Voltage Differential of 50 mV at 100 mA and
380 mV at 100 mA
5.0 V, 3.3 V or 3.0 V ±0.5% Allows Use as a Regulator or Reference
Extremely Tight Line and Load Regulation
Requires Only a 1.0 mF Output Capacitor for Stability
Internal Current and Thermal Limiting
PbFree Packages are Available
NCV Prefix for Automotive and Other Applications Requiring Site
and Control Changes
LP2951 Additional Features
Error Output Signals an Out of Regulation Condition
Output Programmable from 1.25 V to 29 V
Logic Level Shutdown Input
(See Following Page for Device Information.)
TO92
Z SUFFIX
CASE 29
See detailed ordering and shipping information in the package
dimensions section on pages 14 and 16 of this data sheet.
See general marking information in the device marking
section on page 18 of this data sheet.
ORDERING & MARKING INFORMATION
PIN CONNECTIONS
Pin: 1. Output
2. Ground
3. Input
DPAK
DT SUFFIX
CASE 369C
Heatsink surface (shown as terminal 4 in
case outline drawing) is connected to Pin 2.
12 3
(Top View)
Pin: 1. Input
2. Ground
3. Output
8
1
8
1
8
1
PIN CONNECTIONS
18
7
6
5
2
3
4
(Top View)
Output
Sense
Shutdown
Input
Feedback
Error Output
VO Tap
GND
SOIC8
D SUFFIX
CASE 751
PDIP8
N SUFFIX
CASE 626
Micro8E
DM SUFFIX
CASE 846A
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12
3
4
123
12
BENT LEAD
TAPE & REEL
AMMO PACK
STRAIGHT LEAD
BULK PACK
3
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DEVICE INFORMATION
Package
Output Voltage Operating Ambient
Temperature Range
3.0 V 3.3 V 5.0 V Adjustable
TO92
Suffix Z
LP2950CZ3.0
LP2950ACZ3.0
LP2950CZ3.3
LP2950ACZ3.3
LP2950CZ5.0
LP2950ACZ5.0
Not
Available TA = 40° to +125°C
DPAK
Suffix DT
LP2950CDT3.0
LP2950ACDT3.0
LP2950CDT3.3
LP2950ACDT3.3
LP2950CDT5.0
LP2950ACDT5.0
Not
Available TA = 40° to +125°C
SOIC8NCV2951ACD3.3R2 NCV2951ACDR2 NCV2951CDR2 TA = 40° to +125°C
SOIC8
Suffix D
LP2951CD3.0
LP2951ACD3.0
LP2951CD3.3
LP2951ACD3.3
LP2951CD
LP2951ACD
LP2951CD
LP2951ACD TA = 40° to +125°C
Micro8
Suffix DM
LP2951CDM3.0
LP2951ACDM3.0
LP2951CDM3.3
LP2951ACDM3.3
LP2951CDM
LP2951ACDM
LP2951CDM
LP2951ACDM TA = 40° to +125°C
DIP8
Suffix N
LP2951CN3.0
LP2951ACN3.0
LP2951CN3.3
LP2951ACN3.3
LP2951CN
LP2951ACN
LP2951CN
LP2951ACN TA = 40° to +125°C
LP2950Cxxx / LP2951Cxxxx 1% Output Voltage Precision at TA = 25°C
LP2950ACxxx / LP2951ACxxxx 0.5% Output Voltage Precision at TA = 25°C
From
CMOS/TTL
3
Figure 1. Representative Block Diagrams
This device contains 34 active transistors.
LP2950CZ5.0
Battery or
Unregulated DC
GND 2
Output 5.0 V/100 mA
1
Input
3
1.23 V
Reference
Error Amplifier
182 k
60 k
1.0 mF
GND 4
182 k
60 k
1.23 V
Reference
1.0 mF
LP2951CD or CN
Error
Amplifier
Battery or
Unregulated DC
Shutdown
Error
Output
5
VO Tap
Feedback
6
7
Input 8 Output 1Sense 2 5.0 V/100 mA
330 k
To CMOS/TTL
75 mV/
60 mV
Error Detection
Comparator
50 k
60 k
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MAXIMUM RATINGS (TA = 25°C, unless otherwise noted.)
Rating Symbol Value Unit
Input Voltage VCC 30 Vdc
Peak Transient Input Voltage (t < 20 ms) VCC 32 Vdc
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
Power Dissipation and Thermal Characteristics
ÁÁÁÁ
ÁÁÁÁÁÁÁÁ
ÁÁÁ
Maximum Power Dissipation PDInternally Limited W
Case 751(SOIC8) D Suffix
Thermal Resistance, JunctiontoAmbient RqJA 180 °C/W
Thermal Resistance, JunctiontoCase RqJC 45 °C/W
Case 369A (DPAK) DT Suffix (Note 1)
Thermal Resistance, JunctiontoAmbient RqJA 92 °C/W
Thermal Resistance, JunctiontoCase RqJC 6.0 °C/W
Case 29 (TO226AA/TO92) Z Suffix
Thermal Resistance, JunctiontoAmbient RqJA 160 °C/W
Thermal Resistance, JunctiontoCase RqJC 83 °C/W
Case 626 N Suffix
Thermal Resistance, JunctiontoAmbient RqJA 105 °C/W
Case 846A (Micro8) DM Suffix
Thermal Resistance, JunctiontoAmbient RqJA 240 °C/W
Feedback Input Voltage Vfb 1.5 to +30 Vdc
Shutdown Input Voltage Vsd 0.3 to +30 Vdc
Error Comparator Output Voltage Verr 0.3 to +30 Vdc
Operating Ambient Temperature Range TA40 to +125 °C
Maximum Die Junction Temperature Range TJ+150 °C
Storage Temperature Range Tstg 65 to +150 °C
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
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ELECTRICAL CHARACTERISTICS (Vin = VO + 1.0 V, IO = 100 mA, CO = 1.0 mF, TA = 25°C [Note 3],
unless otherwise noted.)
Characteristic Symbol Min Typ Max Unit
Output Voltage, 5.0 V Versions VOV
Vin = 6.0 V, IO = 100 mA, TA = 25°C
LP2950C5.0/LP2951C/NCV2951C* 4.950 5.000 5.050
LP2950AC5.0/LP2951AC/NCV2951AC* 4.975 5.000 5.025
TA = 40 to +125°C
LP2950C5.0/LP2951C/NCV2951C* 4.900 5.100
LP2950AC5.0/LP2951AC/NCV2951AC* 4.940 5.060
Vin = 6.0 to 30 V, IO = 100 mA to 100 mA, TA = 40 to +125°C
LP2950C5.0/LP2951C/NCV2951C* 4.880 5.120
LP2950AC5.0/LP2951AC/NCV2951AC* 4.925 5.075
Output Voltage, 3.3 V Versions VOV
Vin = 4.3 V, IO = 100 mA, TA = 25°C
LP2950C3.3/LP2951C3.3 3.267 3.300 3.333
LP2950AC3.3/LP2951AC3.3/NCV2951AC3.3* 3.284 3.300 3.317
TA = 40 to +125°C
LP2950C3.3/LP2951C3.3 3.234 3.366
LP2950AC3.3/LP2951AC3.3/NCV2951AC3.3* 3.260 3.340
Vin = 4.3 to 30 V, IO = 100 mA to 100 mA, TA = 40 to +125°C
LP2950C3.3/LP2951C3.3 3.221 3.379
LP2950AC3.3/LP2951AC3.3/NCV2951AC3.3* 3.254 3.346
Output Voltage, 3.0 V Versions VOV
Vin = 4.0 V, IO = 100 mA, TA = 25°C
LP2950C3.0/LP2951C3.0 2.970 3.000 3.030
LP2950AC3.0/LP2951AC3.0 2.985 3.000 3.015
TA = 40 to +125°C
LP2950C3.0/LP2951C3.0 2.940 3.060
LP2950AC3.0/LP2951AC3.0 2.964 3.036
Vin = 4.0 to 30 V, IO = 100 mA to 100 mA, TA = 40 to +125°C
LP2950C3.0/LP2951C3.0 2.928 3.072
LP2950AC3.0/LP2951AC3.0 2.958 3.042
1. The JunctiontoAmbient Thermal Resistance is determined by PCB copper area per Figure 29.
2. This device series contains ESD protection and exceeds the following tests:
Human Body Model (HBM), 2000 V, Class 2, JESD22 A114C
Machine Model (MM), 200 V, Class B, JESD22 A115A
Charged Device Model (CDM), 2000 V, Class IV, JESD22 C101C
3. Low duty pulse techniques are used during test to maintain junction temperature as close to ambient as possible.
4. VO(nom) is the part number voltage option.
5. Noise tests on the LP2951 are made with a 0.01 mF capacitor connected across Pins 7 and 1.
*NCV prefix is for automotive and other applications requiring site and change control.
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ELECTRICAL CHARACTERISTICS (continued) (Vin = VO + 1.0 V, IO = 100 mA, CO = 1.0 mF, TA = 25°C [Note 8],
unless otherwise noted.)
Characteristic Symbol Min Typ Max Unit
Line Regulation (Vin = VO(nom) +1.0 V to 30 V) (Note 9) Regline %
LP2950CXX/LP2951C/LP2951CXX/NCV2951C* 0.08 0.20
LP2950ACXX/LP2951AC/LP2951ACXX/NCV2951AC* 0.04 0.10
Load Regulation (IO = 100 mA to 100 mA) Regload %
LP2950CXX/LP2951C/LP2951CXX/NCV2951C* 0.13 0.20
LP2950ACXX/LP2951AC/LP2951ACXX/NCV2951AC* 0.05 0.10
Dropout Voltage VI VOmV
IO = 100 mA30 80
IO = 100 mA 350 450
Supply Bias Current ICC
IO = 100 mA93 120 mA
IO = 100 mA 4.0 12 mA
Dropout Supply Bias Current (Vin = VO(nom) 0.5 V,
IO = 100 mA) (Note 9)
ICCdropout 110 170 mA
Current Limit (VO Shorted to Ground) ILimit 220 300 mA
Thermal Regulation Regthermal 0.05 0.20 %/W
Output Noise Voltage (10 Hz to 100 kHz) (Note 10) VnmVrms
CL = 1.0 mF126
CL = 100 mF56
LP2951A/LP2951AC Only
Reference Voltage (TA = 25°C) Vref V
LP2951C/LP2951CXX/NCV2951C* 1.210 1.235 1.260
LP2951AC/LP2951ACXX/NCV2951AC* 1.220 1.235 1.250
Reference Voltage (TA = 40 to +125°C) Vref V
LP2951C/LP2951CXX/NCV2951C* 1.200 1.270
LP2951AC/LP2951ACXX/NCV2951AC* 1.200 1.260
Reference Voltage (TA = 40 to +125°C) Vref V
IO = 100 mA to 100 mA, Vin = 23 to 30 V
LP2951C/LP2951CXX/NCV2951C* 1.185 1.285
LP2951AC/LP2951ACXX/NCV2951AC* 1.190 1.270
Feedback Pin Bias Current IFB 15 40 nA
Error Comparator
Output Leakage Current (VOH = 30 V) Ilkg 0.01 1.0 mA
Output Low Voltage (Vin = 4.5 V, IOL = 400 mA) VOL 150 250 mV
Upper Threshold Voltage (Vin = 6.0 V) Vthu 40 45 mV
Lower Threshold Voltage (Vin = 6.0 V) Vthl 60 95 mV
Hysteresis (Vin = 6.0 V) Vhy 15 mV
Shutdown Input
Input Logic Voltage Vshtdn V
Logic “0” (Regulator “On”) 00.7
Logic “1” (Regulator “Off”) 2.0 30
Shutdown Pin Input Current Ishtdn mA
Vshtdn = 2.4 V 35 50
Vshtdn = 30 V 450 600
Regulator Output Current in Shutdown Mode Ioff 3.0 10 mA
(Vin = 30 V, Vshtdn = 2.0 V, VO = 0, Pin 6 Connected to Pin 7)
6. The JunctiontoAmbient Thermal Resistance is determined by PCB copper area per Figure 29.
7. ESD data available upon request.
8. Low duty pulse techniques are used during test to maintain junction temperature as close to ambient as possible.
9. VO(nom) is the part number voltage option.
10.Noise tests on the LP2951 are made with a 0.01 mF capacitor connected across Pins 7 and 1.
*NCV prefix is for automotive and other applications requiring site and change control.
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DEFINITIONS
Dropout Voltage The input/output voltage differential
at which the regulator output no longer maintains regulation
against further reductions in input voltage. Measured when
the output drops 100 mV below its nominal value (which is
measured at 1.0 V differential), dropout voltage is affected
by junction temperature, load current and minimum input
supply requirements.
Line Regulation The change in output voltage for a
change in input voltage. The measurement is made under
conditions of low dissipation or by using pulse techniques
such that average chip temperature is not significantly
affected.
Load Regulation The change in output voltage for a
change in load current at constant chip temperature.
Maximum Power Dissipation The maximum total
device dissipation for which the regulator will operate
within specifications.
Bias Current Current which is used to operate the
regulator chip and is not delivered to the load.
Output Noise Voltage The RMS ac voltage at the
output, with constant load and no input ripple, measured
over a specified frequency range.
Leakage Current Current drawn through a bipolar
transistor collectorbase junction, under a specified
collector voltage, when the transistor is “off”.
Upper Threshold Voltage Voltage applied to the
comparator input terminal, below the reference voltage
which is applied to the other comparator input terminal,
which causes the comparator output to change state from a
logic “0” to “1”.
Lower Threshold Voltage Voltage applied to the
comparator input terminal, below the reference voltage
which is applied to the other comparator input terminal,
which causes the comparator output to change state from a
logic “1” to “0”.
Hysteresis The difference between Lower Threshold
voltage and Upper Threshold voltage.
25°C
Figure 2. Quiescent Current
, OUTPUT VOLTAGE (V)
Vout
, OUTPUT VOLTAGE (V)
Vout
-50
5.00
0
6.0
0.1
10
TA, AMBIENT TEMPERATURE (°C)
Vin, INPUT VOLTAGE (V)
LP2950/LP2951 BIAS CURRENT (mA)
IL, LOAD CURRENT (mA)
Figure 3. 5.0 V Dropout Characteristics over
Load
Figure 4. Output Voltage versus Temperature
1.0 10 100 1.0 2.0 3.0 4.0 5.0 6.0
0 50 100 150
1.0
0.1
0.01
5.0
4.0
3.0
2.0
1.0
0
4.99
4.98
4.97
4.96
4.95
RL = 50 kW
RL = 50 W
LP2951C
TA = 25°C
LP2951C
200
, OUTPUT VOLTAGE (V)
Vout
0
6.0
Vin, INPUT VOLTAGE (V)
Figure 5. 5.0 V Dropout Characteristics with
RL = 50 W
1.0 2.0 3.0 4.0
5.0
3.0
2.0
1.0
0
6.05.0
4.0
125°C40°C
LP2951C
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RL
DROPOUT VOLTAGE (mV) = 50
T, TEMPERATURE (°C)
0
8.0
-50
550
-100
4.70
5.0
0.1
400
, INPUT VOLTAGE (V)
t, TIME (ms)
SHUTDOWN AND OUTPUT VOLTAGE (V)
t, TIME (ms)
, OUTPUT VOLTAGE (V)
Vin, INPUT VOLTAGE (V)
DROPOUT VOLTAGE (mV)
IO, OUTPUT CURRENT (mA)
1.0 10 100
0 50 100 150 4.74 4.78 4.82 4.86
100 200 300
4.90
400 500 600 700 800 0 100 200 300 400
300
200
0
500
450
400
300
7.5
7.0
6.5
6.0
5.5
4.0
3.0
1.0
0
5.0
3.0
1.0
-1.0
RL = 50
Vin Decreasing
Vin Increasing
Vin
Vout
RL = 50 k
TA = 25°C
CL = 1.0 mF
IL = 1.0 mA
VO = 5.0 V
TA = 25°C
IL = 10 mA
Vin = 8.0 V
Vout = 5.0 V
CL = 10 mF
Shutdown Input
350
RL
DROPOUT VOLTAGE (mV) = 50 k
55
50
45
40
30
35
350
250
150
100
2.0
OUTPUT VOLTAGE CHANGE (mV)
4.0
2.0
0
-2.0
-6.0
-4.0
6.0
4.0
2.0
0
50
Vin
Vout
CL = 1.0 mF
TA = 25°C
LP2951C
RL = 330 k
TA = 25°C
0
250
BIAS CURRENT ( A)μ
Vin, INPUT VOLTAGE (V)
Figure 6. Input Current
5.0 10 15 20 25
200
150
100
50
0
0.1 mA Load Current
No Load
Figure 7. Dropout Voltage versus Output Current
Figure 8. Dropout Voltage versus Temperature Figure 9. Error Comparator Output
Figure 10. Line Transient Response Figure 11. LP2951 Enable Transient
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1
0
100
100
4.0
-40
1.8
1.0
80
V
out, OUTPUT CURRENT (mA)
Vin, INPUT VOLTAGE (V)
VOLTAGE NOISE ( V/ Hz)
f, FREQUENCY (Hz)
SHUTDOWN THRESHOLD VOLTAGE (V)
t, TEMPERATURE (°C)
RIPPLE REJECTION (dB)
f, FREQUENCY (Hz)
TA = 25°C
CL = 1.0 mF
Vin = 6.0 V
Vout = 5.0 V
CL = 1.0 mF
μ
CL = 100 mF
IL= 0.1 mA
IL= 100 mA
TA = 25°C
VO = 5.0 V
LP2951C
Output “Off"
Output “On"
TA = 25°C
LP2951CN
60
40
20
0
3.0
2.0
1.0
0
80
60
40
20
0
1.4
1.0
0.8
1.2
1.6
10 100 1.0 k 10 k 100 k
1.0 k 10 k 100 k -20 40 80 120 160
5.0 15 25 35 4010 20 30
60 100 140200
TA = 75°C
4.0
2.0
0
-2.0
-4.0
-6.0
OUTPUT VOLTAGE CHANGE (mV)
0.01
0.1
10
100
1000
10000
0 102030405060708090100
Output Current (mA)
ESR (ohms)
Unstable Region
Stable Region
Unstable Region for 0.1 mF capacitor only
100 mF
0.1 mF
Vout = 5 V
Lower unstable region is for 0.1 mF only.
1 mF and 100 mF show no instability with low ESR values.
0
200
LOAD CURRENT (mA)
t, TIME (ms)
Figure 12. Load Transient Response
42.50.5 1.5 2 3 3.51
150
100
0
-50
50
Vout
ILoad
OUTPUT VOLTAGE CHANGE (mV)
0
-200
200
400
-400
CL = 1.0 mF
Vout = 5.0 V
IL = 400 mA to 75 mA
TA = 25°C
Figure 13. Ripple Rejection
Figure 14. Output Noise Figure 15. Shutdown Threshold Voltage
versus Temperature
Figure 16. Maximum Rated
Output Current
Figure 17. Output Stability versus Output Capacitor
Change
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APPLICATIONS INFORMATION
Introduction
The LP2950/LP2951 regulators are designed with
internal current limiting and thermal shutdown making them
userfriendly. Typical application circuits for the LP2950
and LP2951 are shown in Figures 20 through 28.
These regulators are not internally compensated and thus
require a 1.0 mF (or greater) capacitance between the
LP2950/LP2951 output terminal and ground for stability.
Most types of aluminum, tantalum or multilayer ceramic
will perform adequately. Solid tantalums or appropriate
multilayer ceramic capacitors are recommended for
operation below 25°C.
At lower values of output current, less output capacitance
is required for output stability. The capacitor can be reduced
to 0.33 mF for currents less than 10 mA, or 0.1 mF for currents
below 1.0 mA. Using the 8 pin versions at voltages less than
5.0 V operates the error amplifier at lower values of gain, so
that more output capacitance is needed for stability. For the
worst case operating condition of a 100 mA load at 1.23 V
output (output Pin 1 connected to the feedback Pin 7) a
minimum capacitance of 3.3 mF is recommended.
The LP2950 will remain stable and in regulation when
operated with no output load. When setting the output
voltage of the LP2951 with external resistors, the resistance
values should be chosen to draw a minimum of 1.0 mA.
A bypass capacitor is recommended across the
LP2950/LP2951 input to ground if more than 4 inches of
wire connects the input to either a battery or power supply
filter capacitor.
Input capacitance at the LP2951 Feedback Pin 7 can
create a pole, causing instability if high value external
resistors are used to set the output voltage. Adding a 100 pF
capacitor between the Output Pin 1 and the Feedback Pin 7
and increasing the output filter capacitor to at least 3.3 mF
will stabilize the feedback loop.
Error Detection Comparator
The comparator switches to a positive logic low whenever
the LP2951 output voltage falls more than approximately
5.0% out of regulation. This value is the comparators
designedin offset voltage of 60 mV divided by the 1.235 V
internal reference. As shown in the representative block
diagram. This trip level remains 5.0% below normal
regardless of the value of regulated output voltage. For
example, the error flag trip level is 4.75 V for a normal 5.0 V
regulated output, or 9.50 V for a 10 V output voltage.
Figure 2 is a timing diagram which shows the ERROR
signal and the regulated output voltage as the input voltage
to the LP2951 is ramped up and down. The ERROR signal
becomes valid (low) at about 1.3 V input. It goes high when
the input reaches about 5.0 V (Vout exceeds about 4.75 V).
Since the LP2951’s dropout voltage is dependent upon the
load current (refer to the curve in the Typical Performance
Characteristics), the input voltage trip point will vary with
load current. The output voltage trip point does not vary
with load.
The error comparator output is an open collector which
requires an external pullup resistor. This resistor may be
returned to the output or some other voltage within the
system. The resistance value should be chosen to be
consistent with the 400 mA sink capability of the error
comparator. A value between 100 k and 1.0 MW is
suggested. No pullup resistance is required if this output is
unused.
When operated in the shutdown mode, the error
comparator output will go high if it has been pulled up to an
external supply. To avoid this invalid response, the error
comparator output should be pulled up to Vout (see
Figure 18).
Figure 18. ERROR Output Timing
5.0 V
4.75 V 4.70 V
4.75 V + Vdropout 4.70 V + Vdropout
1.3 V 1.3 V
Not
Valid Pullup
to Vout
Pullup
to Ext
Output
Voltage
ERROR
Input
Voltage
Not
Valid
Programming the Output Voltage (LP2951)
The LP2951CX may be pinstrapped for the nominal
fixed output voltage using its internal voltage divider by
tying Pin 1 (output) to Pin 2 (sense) and Pin 7 (feedback) to
Pin 6 (5.0 V tap). Alternatively, it may be programmed for
any output voltage between its 1.235 reference voltage and
its 30 V maximum rating. An external pair of resistors is
required, as shown in Figure 19.
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Figure 19. Adjustable Regulator
Error
Output
Shutdown
Input
Vin
Vout
1.23 to 30
V
3.3 mF
0.01 mF
NC
NC
R2
R1
100 k
5
3
Error
SD
GND FB
47
6
VO T
SNS 2
Vout
Vin
8
1
The complete equation for the output voltage is:
Vout +Vref (1)R1ńR2))IFB R1
where Vref is the nominal 1.235 V reference voltage and IFB
is the feedback pin bias current, nominally 20 nA. The
minimum recommended load current of 1.0 mA forces an
upper limit of 1.2 MW on the value of R2, if the regulator
must work with no load. IFB will produce a 2% typical error
in Vout which may be eliminated at room temperature by
adjusting R1. For better accuracy, choosing R2 = 100 k
reduces this error to 0.17% while increasing the resistor
program current to 12 mA. Since the LP2951 typically draws
75 mA at no load with Pin 2 open circuited, the extra 12 mA
of current drawn is often a worthwhile tradeoff for
eliminating the need to set output voltage in test.
Output Noise
In many applications it is desirable to reduce the noise
present at the output. Reducing the regulator bandwidth by
increasing the size of the output capacitor is the only method
for reducing noise on the 3 lead LP2950. However,
increasing the capacitor from 1.0 mF to 220 mF only
decreases the noise from 430 mV to 160 mVrms for a 100 kHz
bandwidth at the 5.0 V output.
Noise can be reduced fourfold by a bypass capacitor
across R1, since it reduces the high frequency gain from 4
to unity. Pick
CBypass [1
2pR1 x 200 Hz
or about 0.01 mF. When doing this, the output capacitor must
be increased to 3.3 mF to maintain stability. These changes
reduce the output noise from 430 mV to 126 mVrms for a
100 kHz bandwidth at 5.0 V output. With bypass
capacitor added, noise no longer scales with output voltage
so that improvements are more dramatic at higher output
voltages.
Figure 20. 1.0 A Regulator with 1.2 V Dropout
0.01 mF
10 k
MTB23P06E
1.0 mF
Unregulated
Input
Error
Output
Shutdown
Input
Vout
5.0 V ±1.0%
0 to 1.0 A
220 mF
2.0 k
5
3
Error
SD
GND FB
47
6
VO T
SNS 2
Vout
Vin
8
1
0.002 mF
1.0 M
LP2951CN
LP2950, LP2951, NCV2951
http://onsemi.com
11
TYPICAL APPLICATIONS
Figure 21. Lithium Ion Battery Cell Charger
1N4001
GND
4.2 V ±0.025 V
NC
NC
50 k
5
3
Error
SD
GND FB
47
6
VO T
SNS 2
Vout
Vin
8
1
0.1 mF
NC
LP2951CN
2.2 mF
330 pF
806 k
1.0%
2.0 M
1.0%
Lithium Ion
Rechargeable
Cell
Unregulated Input
6.0 to 10 Vdc
Figure 22. Low Drift Current Sink
Error
Output
Shutdown
Input
+V = 2.0 to 30 V
1.0 mF
R
5
3
Error
SD
GND FB
47
6
VO T
SNS 2
Vout
Vin
8
1
0.1 mF
Load IL = 1.23/R
IL
Figure 23. Latch Off When Error Flag Occurs
Reset
+Vin
Vout
1.0 mF
NC
NC
R2
R1
470 k
5
3
Error
SD
GND FB
47
6
VO T
SNS 2
Vout
Vin
8
1
LP2951CN
470 k
Error flag occurs when Vin is too
low to maintain Vout, or if Vout is re-
duced by excessive load current.
Normally
Closed
2N3906
Figure 24. 5.0 V Regulator with 2.5 V Sleep Function
*Sleep
Input
+Vin
Vout
3.3 mF
NC
NC
100 k
100 k
470 k
5
3
Error
SD
GND FB
47
6
VO T
SNS 2
Vout
Vin
8
1
LP2951CN 200 k
100 pF
2N3906
47 k
CMOS
Gate
Error
Output
Shutdown
Input
LP2951CN
LP2950, LP2951, NCV2951
http://onsemi.com
12
330 k
Figure 25. Regulator with Early Warning and Auxiliary Output
+Vin
Memory
V+
1.0 mF20
5
3
Error
SD
GND FB
47
6
VO T
SNS 2
Vout
Vin
8
1
LP2951CN
#1
1.0 mF
5
3
Error
SD
GND FB
47
6
VO T
SNS 2
Vout
Vin
8
1
LP2951CN
#2
NC
Reset
VDD
mP
Early Warning
All diodes are 1N4148.
Early Warning flag on low input voltage.
Main output latches off at lower input voltages.
Battery backup on auxiliary output.
Operation: Regulator #1’s Vout is programmed one
diode drop above 5.0 V. Its error flag becomes active
when Vin < 5.7 V. When Vin drops below 5.3 V, the
error flag of regulator #2 becomes active and via Q1
latches the main output “off”. When Vin again exceeds
5.7 V, regulator #1 is back in regulation and the early
warning signal rises, unlatching regulator #2 via D3.
D4
2.7 M
Q1
2N3906
D2
D1
D3
27 k
3.6 V
NiCad
Main
Output
Figure 26. 2.0 A Low Dropout Regulator
+Vin
Vout @ 2.0 A
100 mF
NC
NC
R2
R1
470
5
3
Error
SD
GND FB
47
6
VO T
SNS 2
Vout
Vin
8
1
LP2951CN
MJE2955
4.7 M
Error
Flag
Vout = 1.25V (1.0 + R1/R2)
For 5.0 V output, use internal resistors. Wire Pin 6 to 7,
and wire Pin 2 to +Vout Bus.
20 k
47
4.7 mF
Tant
0.05
680
0.033 mF
2N3906
10 k
Current Limit
Section
220
1000 mF
.33 mF
.01 mF
2N3906
LP2950, LP2951, NCV2951
http://onsemi.com
13
Figure 27. Open Circuit Detector for 4.0 to 20 mA Current Loop
5
3
Error
SD
Gnd FB
47
6
VO T
SNS 2
Vout
Vin
8
1
LP2951CN
NC
Output*
0.1 mF
NC
NC
NC
1N457
1N457 360
1N457
1N4001
24
+ 5.0 V
4.7 k
15
20 mA4
* High for
IL < 3.5 mA
Figure 28. Low Battery Disconnect
2N3906
5
3
Error
SD
Gnd FB
47
6
VO T
SNS 2
Vout
Vin
8
1
LP2951CN
NC
1.0 mF
NC
2
3
1
20
Main V+
Memory V+
6.0 V Lead-Acid
Battery
NiCad Backup
Battery
100 k
31.6 k
MC34164P5
NC
R , THERMAL RESISTANCE
JAθ
JUNCTION‐TO‐AIR ( C/W)°
40
50
60
70
80
90
100
0
0.4
0.8
1.2
1.6
2.0
2.4
010203025155.0
L, LENGTH OF COPPER (mm)
PD(max) for TA = 50°C
Minimum
Size Pad
PD
L
L
ÎÎÎÎ
ÎÎÎÎ
ÎÎÎÎ
ÎÎÎÎ
, MAXIMUM POWER DISSIPATION (W)
Free Air
Mounted
Vertically
RqJA
2.0 oz. Copper
Figure 29. DPAK Thermal Resistance and Maximum
Power Dissipation versus PCB Copper Length
LP2950, LP2951, NCV2951
http://onsemi.com
14
ORDERING INFORMATION (LP2950)
Part Number
Output Voltage
(Volts) Tolerance (%) Package Shipping
LP2950CZ3.0 3.0 1.0 TO92 2000 Units / Bag
LP2950CZ3.0G 3.0 1.0 TO92
(PbFree)
2000 Units / Bag
LP2950CZ3.0RA 3.0 1.0 TO92 2000 Units / Tape & Reel
LP2950CZ3.0RAG 3.0 1.0 TO92
(PbFree)
2000 Units / Tape & Reel
LP2950ACZ3.0 3.0 0.5 TO92 2000 Units / Bag
LP2950ACZ3.0G 3.0 0.5 TO92
(PbFree)
2000 Units / Bag
LP2950ACZ3.0RA 3.0 0.5 TO92 2000 Units / Tape & Reel
LP2950ACZ3.0RAG 3.0 0.5 TO92
(PbFree)
2000 Units / Tape & Reel
LP2950CZ3.3 3.3 1.0 TO92 2000 Units / Bag
LP2950CZ3.3G 3.3 1.0 TO92
(PbFree)
2000 Units / Bag
LP2950CZ3.3RA 3.3 1.0 TO92 2000 Units / Tape & Reel
LP2950CZ3.3RAG 3.3 1.0 TO92
(PbFree)
2000 Units / Tape & Reel
LP2950ACZ3.3 3.3 0.5 TO92 2000 Units / Bag
LP2950ACZ3.3G 3.3 0.5 TO92
(PbFree)
2000 Units / Bag
LP2950ACZ3.3RA 3.3 0.5 TO92 2000 Units / Tape & Reel
LP2950ACZ3.3RAG 3.3 0.5 TO92
(PbFree)
2000 Units / Tape & Reel
LP2950CZ5.0 5.0 1.0 TO92 2000 Units / Bag
LP2950CZ5.0G 5.0 1.0 TO92
(PbFree)
2000 Units / Bag
LP2950CZ5.0RA 5.0 1.0 TO92 2000 Units / Tape & Reel
LP2950CZ5.0RAG 5.0 1.0 TO92
(PbFree)
2000 Units / Tape & Reel
LP2950CZ5.0RP 5.0 1.0 TO92 2000 Units / Ammo Pack
LP2950CZ5.0RPG 5.0 1.0 TO92
(PbFree)
2000 Units / Ammo Pack
LP2950ACZ5.0 5.0 0.5 TO92 2000 Units / Bag
LP2950ACZ5.0G 5.0 0.5 TO92
(PbFree)
2000 Units / Bag
LP2950ACZ5.0RA 5.0 0.5 TO92 2000 Units / Tape & Reel
LP2950ACZ5.0RAG 5.0 0.5 TO92
(PbFree)
2000 Units / Tape & Reel
LP2950CDT3.0 3.0 1.0 DPAK 75 Units / Rail
LP2950CDT3.0G 3.0 1.0 DPAK
(PbFree)
75 Units / Rail
LP2950CDT3.0RK 3.0 1.0 DPAK 2500 Units / Tape & Reel
LP2950CDT3.0RKG 3.0 1.0 DPAK
(PbFree)
2500 Units / Tape & Reel
LP2950ACDT3.0 3.0 0.5 DPAK 75 Units / Rail
LP2950ACDT3.0G 3.0 0.5 DPAK
(PbFree)
75 Units / Rail
LP2950ACDT3.0RK 3.0 0.5 DPAK 2500 Units / Tape & Reel
LP2950ACDT3RKG 3.0 0.5 DPAK
(PbFree)
2500 Units / Tape & Reel
LP2950CDT3.3 3.3 1.0 DPAK 75 Units / Rail
LP2950, LP2951, NCV2951
http://onsemi.com
15
ORDERING INFORMATION (LP2950)
Part Number Shipping
PackageTolerance (%)
Output Voltage
(Volts)
LP2950CDT3.3G 3.3 1.0 DPAK
(PbFree)
75 Units / Rail
LP2950CDT3.3RK 3.3 1.0 DPAK 2500 Units / Tape & Reel
LP2950CDT3.3RKG 3.3 1.0 DPAK
(PbFree)
2500 Units / Tape & Reel
LP2950ACDT3.3 3.3 0.5 DPAK 75 Units / Rail
LP2950ACDT3.3RG 3.3 0.5 DPAK
(PbFree)
2500 Units / Tape & Reel
LP2950ACDT3.3RK 3.3 0.5 DPAK 2500 Units / Tape & Reel
LP2950CDT5.0 5.0 1.0 DPAK 75 Units / Rail
LP2950CDT5.0G 5.0 1.0 DPAK
(PbFree)
75 Units / Rail
LP2950CDT5.0RK 5.0 1.0 DPAK 2500 Units / Tape & Reel
LP2950CDT5.0RKG 5.0 1.0 DPAK
(PbFree)
2500 Units / Tape & Reel
LP2950ACDT5.0 5.0 0.5 DPAK 75 Units / Rail
LP2950ACDT5.0G 5.0 0.5 DPAK
(PbFree)
75 Units / Rail
LP2950ACDT5.0RK 5.0 0.5 DPAK 2500 Units / Tape & Reel
LP2950ACDT5RKG 5.0 0.5 DPAK
(PbFree)
2500 Units / Tape & Reel
For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging
Specifications Brochure, BRD8011/D.
LP2950, LP2951, NCV2951
http://onsemi.com
16
ORDERING INFORMATION (LP2951)
Part Number
Output Voltage
(Volts) Tolerance (%) Package Shipping
LP2951CD3.0 3.0 1.0 SOIC898 Units / Rail
LP2951CD3.0G 3.0 1.0 SOIC8
(PbFree)
98 Units / Rail
LP2951CD3.0R2 3.0 1.0 SOIC82500 Units / Tape & Reel
LP2951CD3.0R2G 3.0 1.0 SOIC8
(PbFree)
2500 Units / Tape & Reel
LP2951ACD3.0 3.0 0.5 SOIC898 Units / Rail
LP2951ACD3.0G 3.0 0.5 SOIC8
(PbFree)
98 Units / Rail
LP2951ACD3.0R2 3.0 0.5 SOIC82500 Units / Tape & Reel
LP2951ACD3.0R2G 3.0 0.5 SOIC8
(PbFree)
2500 Units / Tape & Reel
LP2951CD3.3 3.3 1.0 SOIC898 Units / Rail
LP2951CD3.3G 3.3 1.0 SOIC8
(PbFree)
98 Units / Rail
LP2951CD3.3R2 3.3 1.0 SOIC82500 Units / Tape & Reel
LP2951CD3.3R2G 3.3 1.0 SOIC8
(PbFree)
2500 Units / Tape & Reel
LP2951ACD3.3 3.3 0.5 SOIC898 Units / Rail
LP2951ACD3.3G 3.3 0.5 SOIC8
(PbFree)
98 Units / Rail
LP2951ACD3.3R2 3.3 0.5 SOIC82500 Units / Tape & Reel
LP2951ACD3.3R2G 3.3 0.5 SOIC8
(PbFree)
2500 Units / Tape & Reel
LP2951CD 5.0 or Adj. 1.0 SOIC898 Units / Rail
LP2951CDG 5.0 or Adj. 1.0 SOIC8
(PbFree)
98 Units / Rail
LP2951CDR2 5.0 or Adj. 1.0 SOIC82500 Units / Tape & Reel
LP2951CDR2G 5.0 or Adj. 1.0 SOIC8
(PbFree)
2500 Units / Tape & Reel
LP2951ACD 5.0 or Adj. 0.5 SOIC898 Units / Rail
LP2951ACDG 5.0 or Adj. 0.5 SOIC8
(PbFree)
98 Units / Rail
LP2951ACDR2 5.0 or Adj. 0.5 SOIC82500 Units / Tape & Reel
LP2951ACDR2G 5.0 or Adj. 0.5 SOIC8
(PbFree)
2500 Units / Tape & Reel
LP2951CDM3.0R2 3.0 1.0 Micro8 4000 Units / Tape & Reel
LP2951CDM3.0R2G 3.0 1.0 Micro8
(PbFree)
4000 Units / Tape & Reel
LP2951ACDM3.0R2 3.0 0.5 Micro8 4000 Units / Tape & Reel
LP2951ACDM3.0RG 3.0 0.5 Micro8
(PbFree)
4000 Units / Tape & Reel
LP2951CDM3.3R2 3.3 1.0 Micro8 4000 Units / Tape & Reel
LP2951CDM3.3R2G 3.3 1.0 Micro8
(PbFree)
4000 Units / Tape & Reel
LP2951ACDM3.3RG 3.3 0.5 Micro8
(PbFree)
4000 Units / Tape & Reel
LP2951ACDM3.3R2 3.3 0.5 Micro8 4000 Units / Tape & Reel
LP2951CDMR2 5.0 or Adj. 1.0 Micro8 4000 Units / Tape & Reel
LP2951CDMR2G 5.0 or Adj. 1.0 Micro8
(PbFree)
4000 Units / Tape & Reel
LP2951ACDMR2 5.0 or Adj. 0.5 Micro8 4000 Units / Tape & Reel
LP2950, LP2951, NCV2951
http://onsemi.com
17
ORDERING INFORMATION (LP2951)
Part Number Shipping
PackageTolerance (%)
Output Voltage
(Volts)
LP2951ACDMR2G 5.0 or Adj. 0.5 Micro8
(PbFree)
4000 Units / Tape & Reel
LP2951ACDM5.0R2 5.0 or Adj. 0.5 Micro8 4000 Units / Tape & Reel
LP2951CN3.0 3.0 1.0 PDIP850 Units / Rail
LP2951CN3.0G 3.0 1.0 PDIP8
(PbFree)
50 Units / Rail
LP2951ACN3.0 3.0 0.5 PDIP850 Units / Rail
LP2951ACN3.0G 3.0 0.5 PDIP8
(PbFree)
50 Units / Rail
LP2951CN3.3 3.3 1.0 PDIP850 Units / Rail
LP2951CN3.3G 3.3 1.0 PDIP8
(PbFree)
50 Units / Rail
LP2951ACN3.3 3.3 0.5 PDIP850 Units / Rail
LP2951ACN3.3G 3.3 0.5 PDIP8
(PbFree)
50 Units / Rail
LP2951CN 5.0 or Adj. 1.0 PDIP850 Units / Rail
LP2951CNG 5.0 or Adj. 1.0 PDIP8
(PbFree)
50 Units / Rail
LP2951ACN 5.0 or Adj. 0.5 PDIP850 Units / Rail
LP2951ACNG 5.0 or Adj. 0.5 PDIP8
(PbFree)
50 Units / Rail
For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging
Specifications Brochure, BRD8011/D.
ORDERING INFORMATION (NCV2951)
Part Number
Output Voltage
(Volts) Tolerance (%) Package Shipping
NCV2951ACD3.3R2* 3.3 0.5 SOIC82500 Units / Tape & Reel
NCV2951ACD3.3R2G 3.3 0.5 SOIC8
(PbFree)
2500 Units / Tape & Reel
NCV2951ACDR2* 5.0 or Adj. 0.5 SOIC82500 Units / Tape & Reel
NCV2951ACDR2G 5.0 or Adj. 0.5 SOIC8
(PbFree)
2500 Units / Tape & Reel
NCV2951CDR2* 5.0 or Adj. 1.0 SOIC82500 Units / Tape & Reel
NCV2951CDR2G* 5.0 or Adj. 1.0 SOIC8
(PbFree)
2500 Units / Tape & Reel
For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging
Specifications Brochure, BRD8011/D.
*NCV prefix is for automotive and other applications requiring site and control changes.
LP2950, LP2951, NCV2951
http://onsemi.com
18
xx = 3.0, 3.3, or 5.0
y = 3 or 5
yy = 30, 33, or 50
z = A or C
A = Assembly Location
WL, L = Wafer Lot
YY, Y = Year
WW, W = Work Week
G = PbFree Package
G= PbFree Package
(Note: Microdot may be in either location)
MARKING DIAGRAMS
2950
CZxx
ALYWWG
G
TO92
Z SUFFIX
CASE 029
*
*This marking diagram also applies to NCV2951.
*
50yG
ALYWW
50AyG
ALYWW
50yyG
ALYWW
DPAK
DT SUFFIX
CASE 369C
50AyyG
ALYWW
SOIC8
D SUFFIX
CASE 751
Micro8
DM SUFFIX
CASE 846A
51CN
AWL
YYWWG
PDIP8
N SUFFIX
CASE 626
1
8
51z
ALYW
G
1
8
51z33
ALYW
G
1
8
51z3
ALYW
G
1
8
PAyy
AYWG
G
1
8
Pyy
AYWG
G
1
8
2950A
CZxx
ALYWWG
G
51ACN
AWL
YYWWG
1
8
51CNxx
AWL
YYWWG
1
8
51ACNxx
AWL
YYWWG
1
8
LP2950, LP2951, NCV2951
http://onsemi.com
19
PACKAGE DIMENSIONS
TO226AA/TO92
Z SUFFIX
CASE 2911
ISSUE AM
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
3. CONTOUR OF PACKAGE BEYOND DIMENSION R
IS UNCONTROLLED.
4. LEAD DIMENSION IS UNCONTROLLED IN P AND
BEYOND DIMENSION K MINIMUM.
R
A
P
J
L
B
K
G
H
SECTION XX
C
V
D
N
N
XX
SEATING
PLANE DIM MIN MAX MIN MAX
MILLIMETERSINCHES
A0.175 0.205 4.45 5.20
B0.170 0.210 4.32 5.33
C0.125 0.165 3.18 4.19
D0.016 0.021 0.407 0.533
G0.045 0.055 1.15 1.39
H0.095 0.105 2.42 2.66
J0.015 0.020 0.39 0.50
K0.500 --- 12.70 ---
L0.250 --- 6.35 ---
N0.080 0.105 2.04 2.66
P--- 0.100 --- 2.54
R0.115 --- 2.93 ---
V0.135 --- 3.43 ---
1
NOTES:
1. DIMENSIONING AND TOLERANCING PER
ASME Y14.5M, 1994.
2. CONTROLLING DIMENSION: MILLIMETERS.
3. CONTOUR OF PACKAGE BEYOND
DIMENSION R IS UNCONTROLLED.
4. LEAD DIMENSION IS UNCONTROLLED IN P
AND BEYOND DIMENSION K MINIMUM.
RA
P
J
B
K
G
SECTION XX
C
V
D
N
XX
SEATING
PLANE DIM MIN MAX
MILLIMETERS
A4.45 5.20
B4.32 5.33
C3.18 4.19
D0.40 0.54
G2.40 2.80
J0.39 0.50
K12.70 ---
N2.04 2.66
P1.50 4.00
R2.93 ---
V3.43 ---
1
T
STRAIGHT LEAD
BULK