June 17, 2009
Series of Adjustable Micropower Voltage Regulators
General Description
The LP2950 and LP2951 are micropower voltage regulators
with very low quiescent current (75μA typ.) and very low
dropout voltage (typ. 40mV at light loads and 380mV at
100mA). They are ideally suited for use in battery-powered
systems. Furthermore, the quiescent current of the LP2950/
LP2951 increases only slightly in dropout, prolonging battery
The LP2950-5.0 is available in the surface-mount D-Pak
package, and in the popular 3-pin TO-92 package for pin-
compatibility with older 5V regulators. The 8-lead LP2951 is
available in plastic, ceramic dual-in-line, LLP, or metal can
packages and offers additional system functions.
One such feature is an error flag output which warns of a low
output voltage, often due to falling batteries on the input. It
may be used for a power-on reset. A second feature is the
logic-compatible shutdown input which enables the regulator
to be switched on and off. Also, the part may be pin-strapped
for a 5V, 3V, or 3.3V output (depending on the version), or
programmed from 1.24V to 29V with an external pair of re-
Careful design of the LP2950/LP2951 has minimized all con-
tributions to the error budget. This includes a tight initial
tolerance (.5% typ.), extremely good load and line regulation
(.05% typ.) and a very low output voltage temperature coef-
ficient, making the part useful as a low-power voltage refer-
5V, 3V, and 3.3V versions available
High accuracy output voltage
Guaranteed 100mA output current
Extremely low quiescent current
Low dropout voltage
Extremely tight load and line regulation
Very low temperature coefficient
Use as Regulator or Reference
Needs minimum capacitance for stability
Current and Thermal Limiting
Stable with low-ESR output capacitors (10m to 6Ω)
LP2951 versions only
Error flag warns of output dropout
Logic-controlled electronic shutdown
Output programmable from 1.24 to 29V
Block Diagram and Typical Applications
© 2009 National Semiconductor Corporation 8546 www.national.com
LP2950/LP2951 Series of Adjustable Micropower Voltage Regulators
Connection Diagrams
TO-92 Plastic Package (Z)
Bottom View
Dual-In-Line Packages (N, J)
Surface-Mount Package (M, MM)
Top View
Metal Can Package (H)
Top View
10-Lead Ceramic Surface-Mount Package (WG)
Top View
TO-252 (D-Pak)
Front View
8-Lead LLP
Connect DAP to GND at device pin 4.
Top View
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Ordering Information
Package Temperature
Range VOUT
−40 < TJ < 125 3.0 LP2950ACZ-3.0 2950A CZ3.0 Bag Z03A
LP2950CZ-3.0 2950 CZ3.0 Bag
3.3 LP2950ACZ-3.3 2950A CZ3.3 Bag
LP2950CZ-3.3 2950 CZ3.3 Bag
5.0 LP2950ACZ-5.0 2950A CZ5.0 Bag
LP2950CZ-5.0 2950 CZ5.0 Bag
−40 < TJ < 125 3.0 LP2950CDT-3.0 LP2950CDT-3.0 75 Units/Rail TD03B
LP2950CDTX-3.0 2.5k Units Tape and Reel
3.3 LP2950CDT-3.3 LP2950CDT-3.3 75 Units/Rail
LP2950CDTX-3.3 2.5k Units Tape and Reel
5.0 LP2950CDT-5.0 LP2950CDT-5.0 75 Units/Rail
LP2950CDTX-5.0 2.5k Units Tape and Reel
−40 < TJ < 125 3.0 LP2951ACN-3.0 LP2951ACN-3.0 40 Units/Rail N08E
LP2951CN-3.0 LP2951CN-3.0 40 Units/Rail
3.3 LP2951ACN-3.3 LP2951ACN-3.3 40 Units/Rail
LP2951CN-3.3 LP2951CN-3.3 40 Units/Rail
5.0 LP2951ACN LP2951ACN 40 Units/Rail
LP2951CN LP2951CN 40 Units/Rail
−40 < TJ < 125 3.0 LP2951ACM-3.0 2951ACM30*
(where * is die rev letter)
95 Units/Rail M08A
LP2951ACMX-3.0 2.5k Units Tape and Reel
LP2951CM-3.0 2951CM30*
(where * is die rev letter)
95 Units/Rail
LP2951CMX-3.0 2.5k Units Tape and Reel
3.3 LP2951ACM-3.3 2951ACM33*
(where * is die rev letter)
95 Units/Rail
LP2951ACMX-3.3 2.5k Units Tape and Reel
LP2951CM-3.3 2951CM33*
(where * is die rev letter)
95 Units/Rail
LP2951CMX-3.3 2.5k Units Tape and Reel
5.0 LP2951ACM 2951ACM*
(where * is die rev letter)
95 Units/Rail
LP2951ACMX 2.5k Units Tape and Reel
LP2951CM 2951CM*
(where * is die rev letter)
95 Units/Rail
LP2951CMX 2.5k Units Tape and Reel
−40 < TJ < 125 3.0 LP2951ACMM-3.0 L0BA 1k Units Tape and Reel MUA08A
LP2951ACMMX-3.0 3.5k Units Tape and Reel
LP2951CMM-3.0 L0BB 1k Units Tape and Reel
LP2951CMMX-3.0 3.5k Units Tape and Reel
3.3 LP2951ACMM-3.3 L0CA 1k Units Tape and Reel
LP2951ACMMX-3.3 3.5k Units Tape and Reel
LP2951CMM-3.3 L0CB 1k Units Tape and Reel
LP2951CMMX-3.3 3.5k Units Tape and Reel
5.0 LP2951ACMM L0DA 1k Units Tape and Reel
LP2951ACMMX 3.5k Units Tape and Reel
LP2951CMM L0DB 1k Units Tape and Reel
LP2951CMMX 3.5k Units Tape and Reel
−55 < TJ < 150 5.0 LP2951J/883 See MIL/AERO Datasheet 40 Units/Rail J08A
−55 < TJ < 150 5.0 LP2951H/883 See MIL/AERO Datasheet Tray H08C
−55 < TJ < 150 5.0 LP2951WG/883 See MIL/AERO Datasheet Tray WG10A
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Package Temperature
Range VOUT
8-lead LLP −40 < TJ < 125 3.0 LP2951ACSD-3.0 51AC30 1k Units Tape and Reel SDC08A
LP2951ACSDX-3.0 4.5k Units Tape and Reel
LP2951CSD-3.0 51AC30B 1k Units Tape and Reel
LP2951CSDX-3.0 4.5k Units Tape and Reel
3.3 LP2951ACSD-3.3 51AC33 1k Units Tape and Reel
LP2951ACSDX-3.3 4.5k Units Tape and Reel
LP2951CSD-3.3 51AC33B 1k Units Tape and Reel
LP2951CSDX-3.3 4.5k Units Tape and Reel
5.0 LP2951ACSD 2951AC 1k Units Tape and Reel
LP2951ACSDX 4.5k Units Tape and Reel
LP2951CSD 2951ACB 1k Units Tape and Reel
LP2951CSDX 4.5k Units Tape and Reel
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Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Input Supply Voltage −0.3 to +30V
SHUTDOWN Input Voltage,
Error Comparator Output
Voltage, (Note 9)
FEEDBACK Input Voltage −1.5 to +30V
(Notes 9, 10)
Power Dissipation Internally Limited
Junction Temperature (TJ)+150°C
Ambient Storage Temperature −65° to +150°C
Soldering Dwell Time, Temperature
Vapor Phase
4 seconds, 260°C
10 seconds, 240°C
75 seconds, 219°C
ESD Rating
Human Body Model(Note 18) 2500V
Operating Ratings (Note 1)
Maximum Input Supply Voltage 30V
Junction Temperature Range
(TJ) (Note 8)
LP2951 −55° to +150°C
LP2950AC-XX, LP2950C-XX,
LP2951AC-XX, LP2951C-XX −40° to +125°C
Electrical Characteristics (Note 2)
Parameter Conditions
(Note 2)
LP2951 LP2950AC-XX LP2950C-XX
LP2951AC-XX LP2951C-XX
Tested Tested Design Tested Design
Typ Limit Typ Limit Limit Typ Limit Limit
(Notes 3, 16) (Note 3) (Note 4) (Note 3) (Note 4)
3V Versions (Note 17)
Output Voltage TJ = 25°C 3.0 3.015 3.0 3.015 3.0 3.030 V max
2.985 2.985 2.970 V min
−25°C TJ 85°C 3.0 3.0 3.030 3.0 3.045 V max
2.970 2.955 V min
Full Operating 3.0 3.036 3.0 3.036 3.0 3.060 V max
Temperature Range 2.964 2.964 2.940 V min
Output Voltage 100μA IL 100mA 3.0 3.045 3.0 3.042 3.0 3.072 V max
TJ TJMAX 2.955 2.958 2.928 V min
3.3V Versions (Note 17)
Output Voltage TJ = 25°C 3.3 3.317 3.3 3.317 3.3 3.333 V max
3.284 3.284 3.267 V min
−25°C TJ 85°C 3.3 3.3 3.333 3.3 3.350 V max
3.267 3.251 V min
Full Operating 3.3 3.340 3.3 3.340 3.3 3.366 V max
Temperature Range 3.260 3.260 3.234 V min
Output Voltage 100μA IL 100mA 3.3 3.350 3.3 3.346 3.3 3.379 V max
TJ TJMAX 3.251 3.254 3.221 V min
5V Versions (Note 17)
Output Voltage TJ = 25°C 5.0 5.025 5.0 5.025 5.0 5.05 V max
4.975 4.975 4.95 V min
−25°C TJ 85°C 5.0 5.0 5.05 5.0 5.075 V max
4.95 4.925 V min
Full Operating 5.0 5.06 5.0 5.06 5.0 5.1 V max
Temperature Range 4.94 4.94 4.9 V min
Output Voltage 100μA IL 100mA 5.0 5.075 5.0 5.075 5.0 5.12 V max
TJ TJMAX 4.925 4.925 4.88 V min
All Voltage Options
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Parameter Conditions
(Note 2)
LP2951 LP2950AC-XX LP2950C-XX
LP2951AC-XX LP2951C-XX
Tested Tested Design Tested Design
Typ Limit Typ Limit Limit Typ Limit Limit
(Notes 3, 16) (Note 3) (Note 4) (Note 3) (Note 4)
Output Voltage
(Note 12) 20 120 20 100 50 150 ppm/°C
Line Regulation
(Note 14)
(VONOM + 1)V Vin
30V (Note 15)
0.03 0.1 0.03 0.1 0.04 0.2 % max
0.5 0.2 0.4 % max
Load Regulation
(Note 14)
100μA IL 100mA 0.04 0.1 0.04 0.1 0.1 0.2 % max
0.3 0.2 0.3 % max
Dropout Voltage
(Note 5)
IL = 100μA 80 80 80 mV max
50 150 50 150 50 150 mV max
IL = 100mA 450 450 450 mV max
380 600 380 600 380 600 mV max
Ground IL = 100μA75 120 75 120 75 120 μA max
Current 140 140 140 μA max
IL = 100mA 8 12 8 12 8 12 mA max
14 14 14 mA max
Dropout Vin = (VONOM − 0.5)
110 170 110 170 110 170 μA max
Ground Current IL = 100μA 200 200 200 μA max
Current Limit Vout = 0 160 200 160 200 160 200 mA max
220 220 220 mA max
Thermal Regulation (Note 13) 0.05 0.2 0.05 0.2 0.05 0.2 %/W
Output Noise, CL = 1μF (5V Only) 430 430 430 μV rms
10 Hz to 100 kHz CL = 200μF160 160 160 μV rms
CL = 3.3μF
(Bypass = 0.01μF100 100 100 μV rms
Pins 7 to 1 (LP2951)
8-pin Versions Only LP2951 LP2951AC-XX LP2951C-XX
Reference 1.23
1.25 1.23
1.25 1.23
1.26 V max
Voltage 1.26 1.26 1.27 V max
1.22 1.22 1.21 V min
1.2 1.2 1.2 V min
Reference (Note 7) 1.27 1.27 1.285 V max
Voltage 1.19 1.19 1.185 V min
Feedback Pin 20 40 20 40 20 40 nA max
Bias Current 60 60 60 nA max
Reference Voltage (Note 12) 20 20 50 ppm/°C
Feedback Pin Bias 0.1 0.1 0.1 nA/°C
Current Temperature
Error Comparator
Output Leakage VOH = 30V 0.01 1 0.01 1 0.01 1 μA max
Current 2 2 2μA max
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Parameter Conditions
(Note 2)
LP2951 LP2950AC-XX LP2950C-XX
LP2951AC-XX LP2951C-XX
Tested Tested Design Tested Design
Typ Limit Typ Limit Limit Typ Limit Limit
(Notes 3, 16) (Note 3) (Note 4) (Note 3) (Note 4)
Output Low Vin = (VONOM − 0.5)
150 250 150 250 150 250 mV max
Voltage IOL = 400μA 400 400 400 mV max
Upper Threshold (Note 6) 60 40 60 40 60 40 mV min
Voltage 25 25 25 mV min
Lower Threshold (Note 6) 75 95 75 95 75 95 mV max
Voltage 140 140 140 mV max
Hysteresis (Note 6) 15 15 15 mV
Shutdown Input
Input 1.3 1.3 1.3 V
Logic Low (Regulator ON) 0.6 0.7 0.7 V max
Voltage High (Regulator
2.0 2.0 2.0 V min
Shutdown Pin Input
Vshutdown = 2.4V 30 50 30 50 30 50 μA max
100 100 100 μA max
Vshutdown = 30V 450 600 450 600 450 600 μA max
750 750 750 μA max
Regulator Output
Current in Shutdown
(Note 11) 3 10 3 10 3 10 μA max
20 20 20 μA max
Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the
device is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test conditions, see the
Electrical Characteristics tables.
Note 2: Unless otherwise specified all limits guaranteed for VIN = (VONOM + 1)V, IL = 100μA and CL = 1μF for 5V versions and 2.2μF for 3V and 3.3V versions.
Limits appearing in boldface type apply over the entire junction temperature range for operation. Limits appearing in normal type apply for TA = TJ = 25°C.
Additional conditions for the 8-pin versions are FEEDBACK tied to VTAP, OUTPUT tied to SENSE, and VSHUTDOWN 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 100 mV 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 Vin =
(VONOM + 1)V. To express these thresholds in terms of output voltage change, multiply by the error amplifier gain = Vout/Vref = (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 × 5V/1.235V = 384 mV. Thresholds remain constant
as a percent of Vout as Vout is varied, with the dropout warning occurring at typically 5% below nominal, 7.5% guaranteed.
Note 7: Vref Vout (Vin − 1V), 2.3V Vin 30V, 100μA IL 100mA, TJ TJMAX.
Note 8: The junction-to-ambient thermal resistances are as follows: 180°C/W and 160°C/W for the TO-92 package with 0.40 inch and 0.25 inch leads to the
printed circuit board (PCB) respectively, 105°C/W for the molded plastic DIP (N), 130°C/W for the ceramic DIP (J), 160°C/W for the molded plastic SOP (M), 200°
C/W for the molded plastic MSOP (MM), and 160°C/W for the metal can package (H). The above thermal resistances for the N, J, M, and MM packages apply
when the package is soldered directly to the PCB. Junction-to-case thermal resistance for the H package is 20°C/W. Junction-to-case thermal resistance for the
TO-252 package is 5.4°C/W. The value of θJA for the LLP package is typically 51°C/W but is dependent on the PCB trace area, trace material, and the number
of layers and thermal vias. For details of thermal resistance and power dissipation for the LLP package, refer to Application Note AN-1187.
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
Note 11: Vshutdown 2V, Vin 30V, Vout = 0, Feedback pin tied to VTAP.
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 VIN = 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 under the specification for thermal regulation.
Note 15: Line regulation for the LP2951 is tested at 150°C for IL = 1mA. For IL = 100μA and TJ = 125°C, line regulation is guaranteed by design to 0.2%. See
Typical Performance Characteristics for line regulation versus temperature and load current.
Note 16: A Military RETS specification is available on request. At time of printing, the LP2951 RETS specification complied with the boldface limits in this column.
The LP2951H, WG, or J may also be procured as Standard Military Drawing Spec #5962-3870501MGA, MXA, or MPA.
Note 17: All LP2950 devices have the nominal output voltage coded as the last two digits of the part number. In the LP2951 products, the 3.0V and 3.3V versions
are designated by the last two digits, but the 5V version is denoted with no code at this location of the part number (refer to ordering information table).
Note 18: Human Body Model 1.5kΩ in series with 100pF.
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Typical Performance Characteristics
Quiescent Current
Dropout Characteristics
Input Current
Input Current
Output Voltage vs. Temperature of 3
Representative Units
Quiescent Current
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Quiescent Current
Quiescent Current
Quiescent Current
Short Circuit Current
Dropout Voltage
Dropout Voltage
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LP2951 Minimum Operating Voltage
LP2951 Feedback Bias Current
LP2951 Feedback Pin Current
LP2951 Error Comparator Output
LP2951 Comparator Sink Current
Line Transient Response
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Load Transient Response
Load Transient Response
LP2951 Enable Transient
Output Impedance
Ripple Rejection
Ripple Rejection
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Ripple Rejection
LP2951 Output Noise
LP2951 Divider Resistance
Shutdown Threshold Voltage
Line Regulation
LP2951 Maximum Rated Output Current
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LP2950 Maximum Rated Output Current
Thermal Response
Output Capacitor ESR Range
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Application Hints
A 1.0μF (or greater) capacitor is required between the output
and ground for stability at output voltages of 5V or more. At
lower output voltages, more capacitance is required (2.2μF or
more is recommended for 3V and 3.3V versions). Without this
capacitor the part will oscillate. Most types of tantalum or alu-
minum electrolytics work fine here; even film types work but
are not recommended for reasons of cost. Many aluminum
electrolytics have electrolytes that freeze at about −30°C, so
solid tantalums are recommended for operation below −25°
C. The important parameters of the capacitor are an ESR of
about 5Ω or less and a resonant frequency above 500kHz.
The value of this capacitor may be increased without limit.
Ceramic capacitors whose value is greater than 1000pF
should not be connected directly from the LP2951 output to
ground. Ceramic capacitors typically have ESR values in the
range of 5 to 10m, a value below the lower limit for stable
operation (see curve Output Capacitor ESR Range).
The reason for the lower ESR limit is that the loop compen-
sation of the part relies on the ESR of the output capacitor to
provide the zero that gives added phase lead. The ESR of
ceramic capacitors is so low that this phase lead does not
occur, significantly reducing phase margin. A ceramic output
capacitor can be used if a series resistance is added (recom-
mended value of resistance about 0.1 to 2Ω).
At lower values of output current, less output capacitance is
required for stability. The capacitor can be reduced to
0.33μF for currents below 10mA or 0.1μF for currents below
1mA. Using the adjustable versions at voltages below 5V runs
the error amplifier at lower gains so that more output capaci-
tance is needed. For the worst-case situation of a 100mA load
at 1.23V output (Output shorted to Feedback) a 3.3μF (or
greater) capacitor should be used.
Unlike many other regulators, the LP2950 will remain stable
and in regulation with no load in addition to the internal voltage
divider. This is especially important in CMOS RAM keep-alive
applications. When setting the output voltage of the LP2951
versions with external resistors, a minimum load of 1μA is
A 1μF tantalum, ceramic or aluminum electrolytic capacitor
should be placed from the LP2950/LP2951 input to ground if
there is more than 10 inches of wire between the input and
the AC filter capacitor or if a battery is used as the input.
Stray capacitance to the LP2951 Feedback terminal can
cause instability. This may especially be a problem when us-
ing high value external resistors to set the output voltage.
Adding a 100pF capacitor between Output and Feedback and
increasing the output capacitor to at least 3.3μF will fix this
The comparator produces a logic low output whenever the
LP2951 output falls out of regulation by more than approxi-
mately 5%. This figure is the comparator's built-in offset of
about 60mV divided by the 1.235 reference voltage. (Refer to
the block diagram in the front of the datasheet.) This trip level
remains “5% below normal” regardless of the programmed
output voltage of the 2951. For example, the error flag trip
level is typically 4.75V for a 5V output or 11.4V for a 12V out-
put. The out of regulation condition may be due either to low
input voltage, current limiting, or thermal limiting.
Figure 1 below gives a timing diagram depicting the ER-
ROR signal and the regulated output voltage as the LP2951
input is ramped up and down. For 5V versions, the ERROR
signal becomes valid (low) at about 1.3V input. It goes high
at about 5V input (the input voltage at which VOUT = 4.75V).
Since the LP2951's dropout voltage is load-dependent (see
curve in typical performance characteristics), the input volt-
age trip point (about 5V) will vary with the load current. The
output voltage trip point (approx. 4.75V) does not vary with
The error comparator has an open-collector output which re-
quires an external pull up resistor. This resistor may be re-
turned to the output or some other supply voltage depending
on system requirements. In determining a value for this re-
sistor, note that while the output is rated to sink 400μA, this
sink current adds to battery drain in a low battery condition.
Suggested values range from 100k to 1 MΩ. The resistor is
not required if this output is unused.
*When VIN 1.3V, the error flag pin becomes a high impedance, and the
error flag voltage rises to its pull-up voltage. Using VOUT as the pull-up volt-
age (see Figure 2), rather than an external 5V source, will keep the error flag
voltage under 1.2V (typ.) in this condition. The user may wish to divide down
the error flag voltage using equal-value resistors (10k suggested), to en-
sure a low-level logic signal during any fault condition, while still allowing a
valid high logic level during normal operation.
FIGURE 1. ERROR Output Timing
The LP2951 may be pin-strapped for the nominal fixed output
voltage using its internal voltage divider by tying the output
and sense pins together, and also tying the feedback and
VTAP pins together. Alternatively, it may be programmed for
any output voltage between its 1.235V reference and its 30V
maximum rating. As seen in Figure 2, an external pair of re-
sistors is required.
The complete equation for the output voltage is
where VREF is the nominal 1.235 reference voltage and IFB is
the feedback pin bias current, nominally −20nA. The minimum
recommended load current of 1μA forces an upper limit of 1.2
MΩ on the value of R2, if the regulator must work with no load
(a condition often found in CMOS in standby). IFB will produce
a 2% typical error in VOUT which may be eliminated at room
temperature by trimming R1. For better accuracy, choosing
R2 = 100k reduces this error to 0.17% while increasing the
resistor program current to 12μA. Since the LP2951 typically
draws 60μA at no load with Pin 2 open-circuited, this is a small
price to pay.
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*See Application Hints
**Drive with TTL-high to shut down. Ground or leave open if shutdown fea-
ture is not to be used.
Note: Pins 2 and 6 are left open.
FIGURE 2. Adjustable Regulator
In reference applications it may be advantageous to reduce
the AC noise present at the output. One method is to reduce
the regulator bandwidth by increasing the size of the output
capacitor. This is the only way noise can be reduced on the
3 lead LP2950 but is relatively inefficient, as increasing the
capacitor from 1μF to 220μF only decreases the noise from
430μV to 160μV rms for a 100kHz bandwidth at 5V output.
Noise can be reduced fourfold by a bypass capacitor across
R1, since it reduces the high frequency gain from 4 to unity.
or about 0.01μF. When doing this, the output capacitor must
be increased to 3.3μF to maintain stability. These changes
reduce the output noise from 430μV to 100μV rms for a
100kHz bandwidth at 5V output. With the bypass capacitor
added, noise no longer scales with output voltage so that im-
provements are more dramatic at higher output voltages.
Typical Applications
1A Regulator with 1.2V Dropout
300mA Regulator with 0.75V Dropout
Wide Input Voltage Range Current Limiter
*Minimum input-output voltage ranges from 40mV to 400mV, depending on load
current. Current limit is typically 160mA.
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Low Drift Current Source
5 Volt Current Limiter
*Minimum input-output voltage ranges from 40mV to 400mV, depending on load
current. Current limit is typically 160mA.
Regulator with Early Warning and Auxiliary Output
Early warning flag on low input voltage
Main output latches off at lower input voltages
Battery backup on auxiliary output
Operation: Reg. #1's Vout is programmed one diode drop above 5V. Its error
flag becomes active when Vin 5.7V. When Vin drops below 5.3V, the error flag
of Reg. #2 becomes active and via Q1 latches the main output off. When Vin again
exceeds 5.7V Reg. #1 is back in regulation and the early warning signal rises,
unlatching Reg. #2 via D3.
Latch Off When Error Flag Occurs
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2 Ampere Low Dropout Regulator
For 5Vout, use internal resistors. Wire pin 6 to 7, & wire pin 2 to +Vout Bus.
5V Regulator with 2.5V Sleep Function
*High input lowers Vout to 2.5V
Open Circuit Detector for 4 20mA Current Loop
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