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FEATURES
LP2951. . . D (SOIC) OR DGK (MSOP) PACKAGE
(TOP VIEW)
LP2950. . . LP (TO-226/TO-92) PACKAGE
(TOP VIEW)
OUTPUT
GND
INPUT
GND
LP2950. . . KVU (PowerFLEXt) PACKAGE
(TOP VIEW)
1
2
3
4
8
7
6
5
INPUT
FEEDBACK
VTAP
ERROR
OUTPUT
SENSE
SHUTDOWN
GND
LP2951. . . DRJ (QFN) PACKAGE
(TOP VIEW)
GND
OUTPUT
INPUT
ERROR
OUTPUT 2
3
4
18
7
6
5
SENSE
SHUTDOWN
GND
VTAP
FEEDBACK
INPUT
DESCRIPTION/ORDERING INFORMATION
LP2950 , , LP2951ADJUSTABLE MICROPOWER VOLTAGE REGULATORS
WITH SHUTDOWN
SLVS582C APRIL 2006 REVISED SEPTEMBER 2006
Wide Input Range up to 30 V Current- and Thermal-Limiting FeaturesRated Output Current of 100 mA LP2950 Only (3-Pin Packages)Low Dropout 380 mV (Typ) at 100 mA Fixed-Output Voltages of 5 V, 3.3 V, and 3 VLow Quiescent Current 75 µA (Typ) LP2951 Only (8-Pin Packages)Tight Line Regulation 0.03% (Typ) Fixed- or Adjustable-Output Voltages:5 V/ADJ, 3.3 V/ADJ, and 3 V/ADJTight Load Regulation 0.04% (Typ)
Low-Voltage Error Signal on Falling OutputHigh V
O
Accuracy
Shutdown Capability 1% at 25 °C
Remote Sense Capability for Optimal 2% Over Temperature
Output Regulation and AccuracyCan Be Used as a Regulator or ReferenceStable With Low ESR (>12 m ) Capacitors
The LP2950 and LP2951 devices are bipolar, low-dropout voltage regulators that can accommodate a wide inputsupply-voltage range of up to 30 V. The easy-to-use, 3-pin LP2950 is available in fixed-output voltages of 5 V,3.3 V, and 3 V. However, the 8-pin LP2951 is able to output either a fixed or adjustable output from the samedevice. By tying the OUTPUT and SENSE pins together, and the FEEDBACK and V
TAP
pins together, theLP2951 outputs a fixed 5 V, 3.3 V, or 3 V (depending on the version). Alternatively, by leaving the SENSE andV
TAP
pins open and connecting FEEDBACK to an external resistor divider, the output can be set to any valuebetween 1.235 V to 30 V.
The 8-pin LP2951 also offers additional functionality that makes it particularly suitable for battery-poweredapplications. For example, a logic-compatible shutdown feature allows the regulator to be put in standby modefor power savings. In addition, there is a built-in supervisor reset function in which the ERROR output goes lowwhen V
OUT
drops by 6% of its nominal value for whatever reasons due to a drop in V
IN
, current limiting, orthermal shutdown.
The LP2950 and LP2951 are designed to minimize all error contributions to the output voltage. With a tightoutput tolerance (0.5% at 25 °C), a very low output voltage temperature coefficient (20 ppm typical), extremelygood line and load regulation (0.3% and 0.4% typical), and remote sensing capability, the parts can be used aseither low-power voltage references or 100-mA regulators.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of TexasInstruments semiconductor products and disclaimers thereto appears at the end of this data sheet.PowerFLEX is a trademark of Texas Instruments.
PRODUCTION DATA information is current as of publication date.
Copyright © 2006, Texas Instruments IncorporatedProducts conform to specifications per the terms of the TexasInstruments standard warranty. Production processing does notnecessarily include testing of all parameters.
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LP2950 , , LP2951ADJUSTABLE MICROPOWER VOLTAGE REGULATORSWITH SHUTDOWN
SLVS582C APRIL 2006 REVISED SEPTEMBER 2006
ORDERING INFORMATION
V
OUT
ORDERABLET
A
PACKAGE
(1)
TOP-SIDE MARKING(NOM) PART NUMBER
Bulk of 1000 LP2950-30LPTO-226/TO-92 LP KY5030Reel of 2000 LP2950-30LPRPowerFLEX™/TO-252 KVU Reel of 3000 LP2950-30KVUR PREVIEWQFN DRJ Reel of 1000 LP2951-30DRJR PREVIEW3 V
Tube of 75 LP2951-30DSOIC D KY5130Reel of 2500 LP2951-30DRReel of 2500 LP2951-30DGKRVSSOP DGK PREVIEWReel of 250 LP2951-30DGKTBulk of 1000 LP2950-33LPTO-226/TO-92 LP KY5033Reel of 2000 LP2950-33LPRPowerFLEX/TO-252 KVU Reel of 3000 LP2950-33KVUR PREVIEWQFN DRJ Reel of 1000 LP2951-33DRJR PREVIEW3.3 V
Tube of 75 LP2951-33DSOIC D KY5133Reel of 2500 LP2951-33DR–40 °C to 125 °C Reel of 2500 LP2951-33DGKRVSSOP DGK PREVIEWReel of 250 LP2951-33DGKTBulk of 1000 LP2950-50LP PREVIEWTO-226/TO-92 LP
Reel of 2000 LP2950-50LPR KY5050PowerFLEX/TO-252 KVU Reel of 3000 LP2950-50KVUR PREVIEWQFN DRJ Reel of 1000 LP2951-50DRJR PREVIEW5 V
Tube of 75 LP2951-50DSOIC D KY5150Reel of 2500 LP2951-50DRReel of 2500 LP2951-50DGKRVSSOP DGK PREVIEWReel of 250 LP2951-50DGKTQFN DRJ Reel of 1000 LP2951DRJR PREVIEWTube of 75 LP2951DSOIC-D KY5150ADJ Reel of 2500 LP2951DRReel of 2500 LP2951DGKRVSSOP DGK PREVIEWReel of 250 LP2951DGKT
(1) Package drawings, standard packing quantities, thermal data, symbolization, and PCB design guidelines are available atwww.ti.com/sc/package.
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VOUT
IL 3 100 mA
ERROR
Amplifier
+
1.23-V
Reference
INPUT
OUTPUT
GND
+
+
Unregulated DC
+
See Application
Information
To CMOS
or TTL
VOUT
IL 3 100 mA
ERROR
Amplifier
+
1.235-V
Reference
INPUT
SENSE
GND
+
+
+
Unregulated DC
FEEDBACK
+
VTAP
ERROR
SHUTDOWN
+
330 kW
ERROR Detection Comparator
4
5
6
2
OUTPUT
187
3
From
CMOS
or TTL
60 mV
See Application Information
See Application
Information
LP2950 , , LP2951ADJUSTABLE MICROPOWER VOLTAGE REGULATORS
WITH SHUTDOWN
SLVS582C APRIL 2006 REVISED SEPTEMBER 2006
LP2950 FUNCTIONAL BLOCK DIAGRAM
LP2951 FUNCTIONAL BLOCK DIAGRAM
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Absolute Maximum Ratings
(1)
Recommended Operating Conditions
LP2950 , , LP2951ADJUSTABLE MICROPOWER VOLTAGE REGULATORSWITH SHUTDOWN
SLVS582C APRIL 2006 REVISED SEPTEMBER 2006
over operating free-air temperature range (unless otherwise noted)
MIN MAX UNIT
V
IN
Continuous input voltage range –0.3 30 VV
SHDN
SHUTDOWN input voltage range –1.5 30 VERROR comparator output voltage range
(2)
–1.5 30 VV
FDBK
FEEDBACK input voltage range
(2) (3)
–1.5 30 VD package
(4) (5)
97DGK package
(4) (5)
172θ
JA
Package thermal impedance DRJ package
(4) (6)
46 °C/WKVU package
(4) (6)
30LP package
(4) (5)
140T
J
Operating virtual junction temperature 150 °CT
stg
Storage temperature range –65 150 °C
(1) Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratingsonly, and functional operation of the device at these or any other conditions beyond those indicated under "recommended operatingconditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.(2) May exceed input supply voltage(3) If load is returned to a negative power supply, the output must be diode clamped to GND.(4) Maximum power dissipation is a function of T
J
(max), θ
JA
, and T
A
. The maximum allowable power dissipation at any allowable ambienttemperature is P
D
= (T
J
(max) T
A
)/ θ
JA
. Operating at the absolute maximum T
J
of 150 °C can affect reliability.(5) The package thermal impedance is calculated in accordance with JESD 51-7.(6) The package thermal impedance is calculated in accordance with JESD 51-5.
MIN MAX UNIT
V
IN
Supply input voltage
(1)
30 VT
J
Operating virtual junction temperature –40 125 °C
(1) Minimum V
IN
is the greater of:a. 2 V (25 °C), 2.3 V (over temperature), orb. V
OUT(MAX)
+ Dropout (Max) at rated I
L
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Electrical Characteristics
LP2950 , , LP2951ADJUSTABLE MICROPOWER VOLTAGE REGULATORS
WITH SHUTDOWN
SLVS582C APRIL 2006 REVISED SEPTEMBER 2006
V
IN
= V
OUT
(nominal) + 1 V, I
L
= 100 µA, C
L
= 1 µF (5-V versions) or C
L
= 2.2 µF (3-V and 3.3-V versions),8-pin version: FEEDBACK tied to V
TAP
, OUTPUT tied to SENSE, V
SHUTDOWN
0.7 V
PARAMETER TEST CONDITIONS T
J
MIN TYP MAX UNIT
3-V VERSION (LP295x-30)
25 °C 2.970 3 3.030V
OUT
Output voltage I
L
= 100 µA V–40 °C to 125 °C 2.940 3 3.060
3.3-V VERSION (LP295x-33)
25 °C 3.267 3.3 3.333V
OUT
Output voltage I
L
= 100 µA V–40 °C to 125 °C 3.234 3.3 3.366
5-V VERSION (LP295x-50)
25 °C 4.950 5 5.050V
OUT
Output voltage I
L
= 100 µA V–40 °C to 125 °C 4.900 5 5.100
ALL VOLTAGE OPTIONS
Output voltage temperature
I
L
= 100 µA –40 °C to 125 °C 20 100 ppm/ °Ccoefficient
(1)
25 °C 0.03 0.2Line regulation
(2)
V
IN
= [V
OUT(NOM)
+ 1 V] to 30 V %/V–40 °C to 125 °C 0.425 °C 0.04 0.2Load regulation
(2)
I
L
= 100 µA to 100 mA %–40 °C to 125 °C 0.325 °C 50 80I
L
= 100 µA
–40 °C to 125 °C 150V
IN
V
OUT
Dropout voltage
(3)
mV25 °C 380 450I
L
= 100 mA
–40 °C to 125 °C 60025 °C 75 120I
L
= 100 µAµA–40 °C to 125 °C 140I
GND
GND current
25 °C 8 12I
L
= 100 mA mA–40 °C to 125 °C 1425 °C 110 170V
IN
= V
OUT(NOM)
0.5 V,Dropout ground current µAI
L
= 100 µA
–40 °C to 125 °C 20025 °C 160 200Current limit V
OUT
= 0 V mA–40 °C to 125 °C 220Thermal regulation
(4)
I
L
= 100 µA 25 °C 0.05 0.2 %/WC
L
= 1 µF (5 V only) 430C
L
= 200 µF 160Output noise (RMS),
25 °CµVLP2951-50: C
L
= 3.3 µF,10 Hz to 100 kHz
C
Bypass
= 0.01 µF between pins 1 100and 7
(LP2951-xx) 8-PIN VERSION ONLY ADJ
25 °C 1.222 1.235 1.247–40 °C to 125 °C 1.212 1.257Reference voltage VV
OUT
= V
REF
to (V
IN
1 V),V
IN
= 2.3 V to 30 V, –40 °C to 125 °C 1.200 1.272I
L
= 100 µA to 100 mAReference voltage
25 °C 20 ppm/ °Ctemperature coefficient
(1)
(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. Changes in output voltage due toheating effects are covered under the specification for thermal regulation.(3) Dropout voltage is defined as the input-to-output differential at which the output voltage drops 100 mV, below the value measured at 1-Vdifferential. The minimum input supply voltage of 2 V (2.3 V over temperature) must be observed.(4) Thermal regulation is defined as the change in output voltage at a time (T) after a change in power dissipation is applied, excluding loador line regulation effects. Specifications are for a 50-mA load pulse at V
IN
= 30 V, V
OUT
= 5 V (1.25-W pulse) for t = 10 ms.
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LP2950 , , LP2951ADJUSTABLE MICROPOWER VOLTAGE REGULATORSWITH SHUTDOWN
SLVS582C APRIL 2006 REVISED SEPTEMBER 2006
Electrical Characteristics (continued)V
IN
= V
OUT
(nominal) + 1 V, I
L
= 100 µA, C
L
= 1 µF (5-V versions) or C
L
= 2.2 µF (3-V and 3.3-V versions),8-pin version: FEEDBACK tied to V
TAP
, OUTPUT tied to SENSE, V
SHUTDOWN
0.7 V
PARAMETER TEST CONDITIONS T
J
MIN TYP MAX UNIT
25 °C 20 40FEEDBACK bias current nA–40 °C to 125 °C 60FEEDBACK bias current
25 °C 0.1 nA/ °Ctemperature coefficient
ERROR COMPARATOR
25 °C 0.01 1Output leakage current V
OUT
= 30 V µA–40 °C to 125 °C 225 °C 150 250V
IN
= V
OUT(NOM)
0.5 V,Output low voltage mVI
OL
= 400 µA
–40 °C to 125 °C 40025 °C 40 60Upper threshold voltage
mV( ERROR output high)
(5)
–40 °C to 125 °C 2525 °C 75 95Lower threshold voltage
mV( ERROR output low)
(5)
–40 °C to 125 °C 140Hysteresis
(6)
25 °C 15 mV
SHUTDOWN INPUT
Low (regulator ON) 0.7Input logic voltage –40 °C to 125 °C VHigh (regulator OFF) 225 °C 30 50V
TAP
= 2.4 V
–40 °C to 125 °C 100SHUTDOWN input current µA25 °C 450 600V
TAP
= 30 V
–40 °C to 125 °C 750V
SHUTDOWN
2 V, 25 °C 3 10Regulator output current
V
IN
30 V, V
OUT
= 0, µAin shutdown
–40 °C to 125 °C 20FEEDBACK tied to V
TAP
(5) Comparator thresholds are expressed in terms of a voltage differential equal to the nominal reference voltage (measured atV
IN
V
OUT
= 1 V) minus FEEDBACK terminal voltage. To express these thresholds in terms of output voltage change, multiply by theerror amplifier gain = V
OUT
/V
REF
= (R1 + R2)/R2. For example, at a programmed output voltage of 5 V, the ERROR output is specified togo low when the output drops by 95 mV ×5 V/1.235 V = 384 mV. Thresholds remain constant as a percentage of V
OUT
(as V
OUT
isvaried), with the low-output warning occurring at 6% below nominal (typ) and 7.7% (max).(6) Comparator thresholds are expressed in terms of a voltage differential equal to the nominal reference voltage (measured atV
IN
V
OUT
= 1 V) minus FEEDBACK terminal voltage. To express these thresholds in terms of output voltage change, multiply by theerror amplifier gain = V
OUT
/V
REF
= (R1 + R2)/R2. For example, at a programmed output voltage of 5 V, the ERROR output is specified togo low when the output drops by 95 mV ×5 V/1.235 V = 384 mV. Thresholds remain constant as a percentage of V
OUT
(as V
OUT
isvaried), with the low-output warning occurring at 6% below nominal (typ) and 7.7% (max).
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TYPICAL CHARACTERISTICS
0
10
20
30
40
50
60
70
80
90
100
0 1 2 3 4 5 6 7 8 9 10
VIN Input Voltage V
Input Current µA
R =
L
0.01
0.1
1
10
0.0001 0.001 0.01 0.1
IL Load Current A
Quiescent Current µA
0
20
40
60
80
100
120
140
160
180
200
0 1 2 3 4 5 6 7 8 9 10
VIN Input Voltage V
Input Current µA
R = 50 k
L
0
10
20
30
40
50
60
70
80
90
100
110
120
0 1 2 3 4 5 6 7 8 9 10
VIN Input Voltage V
Input Current mA
LP2950 , , LP2951ADJUSTABLE MICROPOWER VOLTAGE REGULATORS
WITH SHUTDOWN
SLVS582C APRIL 2006 REVISED SEPTEMBER 2006
QUIESCENT CURRENT INPUT CURRENTvs vsLOAD CURRENT INPUT VOLTAGE
INPUT CURRENT INPUT CURRENTvs vsINPUT VOLTAGE INPUT VOLTAGE
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4.900
4.925
4.950
4.975
5.000
5.025
5.050
5.075
5.100
-40 -25 -10 5 20 35 50 65 80 95 110 125
TA Temperature °C
VOUT Output Voltage V
IL= 100 µA
IL= 100 mA
0
10
20
30
40
50
60
70
80
90
100
110
120
0 1 2 3 4 5 6 7 8
VIN Input Voltage V
Quiescent Current µA
IL= 0
0
1
2
3
4
5
6
7
8
0 1 2 3 4 5 6 7 8
VIN Input Voltage V
Quiescent Current µA
IL= 100 mA
0
10
20
30
40
50
60
70
80
90
100
110
120
0 1 2 3 4 5 6 7 8
VIN Input Voltage V
Quiescent Current µA
IL= 1 mA
LP2950 , , LP2951ADJUSTABLE MICROPOWER VOLTAGE REGULATORSWITH SHUTDOWN
SLVS582C APRIL 2006 REVISED SEPTEMBER 2006
TYPICAL CHARACTERISTICS (continued)
OUTPUT VOLTAGE QUIESCENT CURRENTvs vsTEMPERATURE INPUT VOLTAGE
QUIESCENT CURRENT QUIESCENT CURRENTvs vsINPUT VOLTAGE INPUT VOLTAGE
8
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50
55
60
65
70
75
80
85
90
95
100
-40 -25 -10 5 20 35 50 65 80 95 110 125
TA Temperature °C
Quiescent Current µA
IL= 100 µA
VIN = 6 V
5
5.5
6
6.5
7
7.5
8
8.5
9
9.5
10
-40 -25 -10 5 20 35 50 65 80 95 110 125
TA Temperature °C
Quiescent Current mA
IL= 100 mA
VIN = 6 V
50
75
100
125
150
175
200
225
250
-40 -25 -10 5 20 35 50 65 80 95 110 125
TA Temperature °C
Short-Circuit Current A
0
50
100
150
200
250
300
350
400
450
500
-40 -25 -10 5 20 35 50 65 80 95 110 125
TA Temperature °C
(VIN VOUT) Dropout Voltage mV
RL= 100 µA
RL= 100 m A
LP2950 , , LP2951ADJUSTABLE MICROPOWER VOLTAGE REGULATORS
WITH SHUTDOWN
SLVS582C APRIL 2006 REVISED SEPTEMBER 2006
TYPICAL CHARACTERISTICS (continued)
QUIESCENT CURRENT QUIESCENT CURRENTvs vsTEMPERATURE TEMPERATURE
SHORT-CIRCUIT CURRENT DROPOUT VOLTAGEvs vsTEMPERATURE TEMPERATURE
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1.6
1.65
1.7
1.75
1.8
1.85
1.9
1.95
2
-40 -25 -10 5 20 35 50 65 80 95 110 125
TA Temperature °C
Minimum Operating Voltage V
0
50
100
150
200
250
300
350
400
0.0001 0.001 0.01 0.1
IO Output Current A
(VIN VOUT ) Dropout Voltage mV
0
1
2
3
4
5
6
7
8
0 1 2 3 4 5 6 7 8
VIN Input Voltage V
ERROR Output V
50-k resistorto
external5-Vsupply
W
50-k resistor
toV
W
OUT
-20
-15
-10
-5
0
5
10
15
20
25
30
-55 -30 -5 20 45 70 95 120 145
TA Temperature °C
FEEDBACK Bias Current nA
LP2950 , , LP2951ADJUSTABLE MICROPOWER VOLTAGE REGULATORSWITH SHUTDOWN
SLVS582C APRIL 2006 REVISED SEPTEMBER 2006
TYPICAL CHARACTERISTICS (continued)
DROPOUT VOLTAGE LP2951 MINIMUM OPERATING VOLTAGEvs vsOUTPUT CURRENT TEMPERATURE
LP2951 FEEDBACK BIAS CURRENT LP2951 ERROR COMPARATOR OUTPUTvs vsTEMPERATURE INPUT VOLTAGE
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InputVoltage
2V/div
OutputVoltage
80 mV/div
0
0.25
0.5
0.75
1
1.25
1.5
1.75
2
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
VOL Output Low Voltage V
ISINK Sink Current mA
T = 125
A
T = 25
A
T = –40
A
Output Load
100 mA/div
OutputVoltage
100 mV/div
Output Load
100 mA/div
OutputVoltage
100 mV/div
LP2950 , , LP2951ADJUSTABLE MICROPOWER VOLTAGE REGULATORS
WITH SHUTDOWN
SLVS582C APRIL 2006 REVISED SEPTEMBER 2006
TYPICAL CHARACTERISTICS (continued)
LP2951 ERROR COMPARATOR SINK CURRENT LINE TRANSIENT REPONSEvs vsOUTPUT LOW VOLTAGE TIME
LOAD TRANSIENT RESPONSE LOAD TRANSIENT RESPONSEvs vsTIME TIME(V
OUT
= 5 V, C
L
= 1 µF) (V
OUT
= 5 V, C
L
= 10 µF)
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20
30
40
50
60
70
80
90
1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06
f Frequency Hz
Power-Supply Ripple Rejection dB
IL= 100 µA
IL= 0
VIN = 6 V
CL= 1 µF
10 100 1k 10k 100k 1M
0.01
0.1
1
10
100
1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06
f Frequency Hz
Output Impedance Ohm
IL= 1 m A
IL= 100 mA
IL= 100 µA
10 100 1k 10k 100k 1M
LP2950 , , LP2951ADJUSTABLE MICROPOWER VOLTAGE REGULATORSWITH SHUTDOWN
SLVS582C APRIL 2006 REVISED SEPTEMBER 2006
TYPICAL CHARACTERISTICS (continued)
ENABLE TRANSIENT RESPONSE ENABLE TRANSIENT RESPONSEvs vsTIME TIME(C
L
= 1 µF, I
L
= 1 mA) (C
L
= 10 µF, I
L
= 1 mA)
OUTPUT IMPEDANCE RIPPLE REJECTIONvs vsFREQUENCY FREQUENCY
12
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10
20
30
40
50
60
70
80
90
100
1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06
f Frequency Hz
Power-Supply Ripple Rejection dB
IL= 10 mA
IL= 1 mA
VIN = 6 V
CL= 1 µF
10 100 1k 10k 100k 1M
10
20
30
40
50
60
70
80
90
100
1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06
f Frequency Hz
Power-Supply Ripple Rejection dB
IL= 100 mA
IL= 50 mA
VIN = 6 V
CL= 1 µF
10 100 1k 10k 100k 1M
0
50
100
150
200
250
300
350
400
-40 -25 -10 5 20 35 50 65 80 95 110 125
TA Temperature °C
RP2P4 Pin 2 to Pin 4 Resistance k
kW
0
1
2
3
4
5
6
1.E+01 1.E+02 1.E+03 1.E+04 1.E+05
f Frequency Hz
Output Noise µV
CL= 1 µF
CL= 3.3 µF
CL= 200 µF
10 100 1k 10k 100k
LP2950 , , LP2951ADJUSTABLE MICROPOWER VOLTAGE REGULATORS
WITH SHUTDOWN
SLVS582C APRIL 2006 REVISED SEPTEMBER 2006
TYPICAL CHARACTERISTICS (continued)
RIPPLE REJECTION RIPPLE REJECTIONvs vsFREQUENCY FREQUENCY
LP2951 OUTPUT NOISE LP2951 DIVIDER RESISTANCEvs vsFREQUENCY TEMPERATURE
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0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
-40 -25 -10 5 20 35 50 65 80 95 110 125
TA Temperature °C
Input Logic Voltage (OFF to ON) V
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
-40 -25 -10 5 20 35 50 65 80 95 110 125
TA Temperature °C
Input Logic Voltage (ON to OFF) V
-2
-1
0
1
2
3
4
5
6
0 5 10 15 20 25 30
VIN Input Voltage V
Output Voltage Change mV
LP2950 , , LP2951ADJUSTABLE MICROPOWER VOLTAGE REGULATORSWITH SHUTDOWN
SLVS582C APRIL 2006 REVISED SEPTEMBER 2006
TYPICAL CHARACTERISTICS (continued)
SHUTDOWN THRESHOLD VOLTAGE (OFF TO ON) SHUTDOWN THRESHOLD VOLTAGE (ON TO OFF)vs vsTEMPERATURE TEMPERATURE
LINE REGULATION
vsINPUT VOLTAGE
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APPLICATION INFORMATION
Input Capacitor (C
IN
)
Output Capacitor (C
OUT
)
Capacitance Value
ESR Range
LP2950 , , LP2951ADJUSTABLE MICROPOWER VOLTAGE REGULATORS
WITH SHUTDOWN
SLVS582C APRIL 2006 REVISED SEPTEMBER 2006
A 1- µF (tantalum, ceramic, or aluminum) electrolytic capacitor should be placed locally at the input of theLP2950 or LP2951 if there is, or will be, significant impedance between the ac filter capacitor and the input; forexample, if a battery is used as the input or if the ac filter capacitor is located more than 10 in away. There areno ESR requirements for this capacitor, and the capacitance can be increased without limit.
As with most PNP LDOs, stability conditions require the output capacitor to have a minimum capacitance and anESR that falls within a certain range.
For V
OUT
5 V, a minimum of 1 µF is required. For lower V
OUT
, the regulator’s loop gain is running closer tounity gain and, thus, has lower phase margins. Consequently, a larger capacitance is needed for stability. ForV
OUT
= 3 V or 3.3 V, a minimum of 2.2 µF is recommended. For worst case, V
OUT
= 1.23 V (using the ADJversion), a minimum of 3.3 µF is recommended. C
OUT
can be increased without limit and only improves theregulator stability and transient response. Regardless of its value, the output capacitor should have a resonantfrequency less than 500 kHz.
The minimum capacitance values given above are for maximum load current of 100 mA. If the maximumexpected load current is less than 100 mA, then lower values of C
OUT
can be used. For instance, if I
OUT
< 10mA, then only 0.33 µF is required for C
OUT
. For I
OUT
< 1 mA, 0.1 µF is sufficient for stability requirements. Thus,for a worst-case condition of 100-mA load and V
OUT
= V
REF
= 1.235 V (representing the highest load current andlowest loop gain), a minimum C
OUT
of 3.3 µF is recommended.
For the LP2950, no load stability is inherent in the design a desirable feature in CMOS circuits that are put instandby (such as RAM keep-alive applications). If the LP2951 is used with external resistors to set the outputvoltage, a minimum load current of 1 µA is recommended through the resistor divider.
The regulator control loop relies on the ESR of the output capacitor to provide a zero to add sufficient phasemargin to ensure unconditional regulator stability; this requires the closed-loop gain to intersect the open-loopresponse in a region where the open-loop gain rolls off at 20 dB/decade. This ensures that the phase always isless than 180 degrees (phase margin greater than 0 degrees) at unity gain. Thus, a minimum-maximum rangefor the ESR must be observed.
The upper limit of this ESR range is established by the fact that too high an ESR could result in the zerooccurring too soon, causing the gain to roll off too slowly, which, in turn allows a third pole to appear before unitygain and introduce enough phase shift to cause instability. This typically limits the max ESR to approximately5.
Conversely, the lower limit of the ESR is tied to the fact that too low an ESR shifts the zero too far out (pastunity gain) and, thus, allows the gain to roll off at 40 dB/decade at unity gain, with a resulting phase shift ofgreater than 180 degrees. Typically, this limits the minimum ESR to approximately 20 m to 30 m .
For specific ESR requirements, see Typical Characteristics.
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Capacitor Types
C
BYPASS
: Noise and Stability Improvement
f(CBYPASS) ]200 Hz ³CBYPASS +1
2p R1 200 Hz
(1)
ERROR Function (LP2951 Only)
LP2950 , , LP2951ADJUSTABLE MICROPOWER VOLTAGE REGULATORSWITH SHUTDOWN
SLVS582C APRIL 2006 REVISED SEPTEMBER 2006
APPLICATION INFORMATION (continued)
Most tantalum or aluminum electrolytics are suitable for use at the input. Film-type capacitors also work, but athigher cost. When operating at low temperature, care should be taken with aluminum electrolytics, as theirelectrolytes often freeze at –30 °C. For this reason, solid tantalum capacitors should be used at temperaturesbelow –25 °C.
Ceramic capacitors can be used, but due to their low ESR (as low as 5 m to 10 m ), they may not meet theminimum ESR requirement previously discussed. If a ceramic capacitor is used, a series resistor between 0.1 to 2 must be added to meet the minimum ESR requirement. In addition, ceramic capacitors have one glaringdisadvantage that must be taken into account a poor temperature coefficient, where the capacitance can varysignificantly with temperature. For instance, a large-value ceramic capacitor ( 2.2 µF) can lose more than half ofits capacitance as temperature rises from 25 °C to 85 °C. Thus, a 2.2- µF capacitor at 25 °C drops well below theminimum C
OUT
required for stability as ambient temperature rises. For this reason, select an output capacitorthat maintains the minimum 2.2- µF required for stability for the entire operating temperature range.
In the LP2951, an external FEEDBACK pin directly connected to the error amplifier noninverting input can allowstray capacitance to cause instability by shunting the error amplifier feedback to GND, especially at highfrequencies. This is worsened if high-value external resistors are used to set the output voltage, because a highresistance allows the stray capacitance to play a more significant role; i.e., a larger RC time delay is introducedbetween the output of the error amplifier and its FEEDBACK input, leading to more phase shift and lower phasemargin. A solution is to add a 100-pF bypass capacitor (C
BYPASS
) between OUTPUT and FEEDBACK; becauseC
BYPASS
is in parallel with R1, it lowers the impedance seen at FEEDBACK at high frequencies, in effectoffsetting the effect of the parasitic capacitance by providing more feedback at higher frequencies. Morefeedback forces the error amplifier to work at a lower loop gain, so C
OUT
should be increased to a minimum of3.3 µF to improve the regulator’s phase margin.
C
BYPASS
can be also used to reduce output noise in the LP2951. This bypass capacitor reduces the closed loopgain of the error amplifier at the high frequency, so noise no longer scales with the output voltage. Thisimprovement is more noticeable with higher output voltages, because loop gain reduction is greatest. A suitableC
BYPASS
is calculated as shown in Equation 1 :
On the 3-pin LP2950, noise reduction can be achieved by increasing the output capacitor, which causes theregulator bandwidth to be reduced, therefore, eliminating high-frequency noise. However, this method isrelatively inefficient, as increasing C
OUT
from 1 µF to 220 µF only reduces the regulator’s output noise from430 µV to 160 µV (over a 100-kHz bandwidth).
The LP2951 has a low-voltage detection comparator that outputs a logic low when the output voltage drops by6% from its nominal value, and outputs a logic high when V
OUT
has reached 95% of its nominal value. This95% of nominal figure is obtained by dividing the built-in offset of 60 mV by the 1.235-V bandgap reference,and remains independent of the programmed output voltage. For example, the trip-point threshold ( ERRORoutput goes high) typically is 4.75 V for a 5-V output and 11.4 V for a 12-V output. Typically, there is a hysteresisof 15 mV between the thresholds for high and low ERROR output.
A timing diagram is shown in Figure 1 for ERROR vs V
OUT
(5 V), as V
IN
is ramped up and down. ERRORbecomes valid (low) when V
IN
1.3 V. When V
IN
5 V, V
OUT
= 4.75 V, causing ERROR to go high. Because thedropout voltage is load dependent, the output trip-point threshold is reached at different values of V
IN
, dependingon the load current. For instance, at higher load current, ERROR goes high at a slightly higher value of V
IN
, andvice versa for lower load current. The output-voltage trip point remains at 4.75 V, regardless of the load. Notethat when V
IN
1.3 V, the ERROR comparator output is turned off and pulled high to its pullup voltage. If V
OUT
isused as the pullup voltage, rather than an external 5-V source, ERROR typically is 1.2 V. In this condition, anequal resistor divider (10 k is suitable) can be tied to ERROR to divide down the voltage to a valid logic lowduring any fault condition, while still enabling a logic high during normal operation.
16
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5 V
1.3 V
Input
Voltage
Output
Voltage
ERROR
4.75 V
Programming Output Voltage (LP2951 Only)
VOUT +VREF ǒ1)R1
R2Ǔ*IFBR1
(2)
LP2950 , , LP2951ADJUSTABLE MICROPOWER VOLTAGE REGULATORS
WITH SHUTDOWN
SLVS582C APRIL 2006 REVISED SEPTEMBER 2006
APPLICATION INFORMATION (continued)
Figure 1. ERROR Output Timing
Because the ERROR comparator has an open-collector output, an external pullup resistor is required to pull theoutput up to V
OUT
or another supply voltage (up to 30 V). The output of the comparator is rated to sink up to400 µA. A suitable range of values for the pullup resistor is from 100 k to 1 M . If ERROR is not used, it canbe left open.
A unique feature of the LP2951 is its ability to output either a fixed voltage or an adjustable voltage, dependingon the external pin connections. To output the internally programmed fixed voltage, tie the SENSE pin to theOUTPUT pin and the FEEDBACK pin to the V
TAP
pin. Alternatively, a user-programmable voltage ranging fromthe internal 1.235-V reference to a 30-V max can be set by using an external resistor divider pair. The resistordivider is tied to V
OUT
, and the divided-down voltage is tied directly to FEEDBACK for comparison against theinternal 1.235-V reference. To satisfy the steady-state condition in which its two inputs are equal, the erroramplifier drives the output to equal Equation 2 :
Where:
V
REF
= 1.235 V applied across R2I
FB
= FEEDBACK bias current, typically 20 nABLK
A minimum regulator output current of 1 µA must be maintained. Thus, in an application where a no-loadcondition is expected (for example, CMOS circuits in standby), this 1- µA minimum current must be provided bythe resistor pair, effectively imposing a maximum value of R2 = 1.2 M (1.235 V/1.2 M 1µA).
I
FB
= 20 nA introduces an error of 0.02% in V
OUT
. This can be offset by trimming R1. Alternatively, increasingthe divider current makes I
FB
less significant, thus, reducing its error contribution. For instance, using R2 = 100kreduces the error contribution of I
FB
to 0.17% by increasing the divider current to 12 µA. This increase in thedivider current still is small compared to the 600- µA typical quiescent current of the LP2951 under no load.
17Submit Documentation Feedback
PACKAGING INFORMATION
Orderable Device Status (1) Package
Type Package
Drawing Pins Package
Qty Eco Plan (2) Lead/Ball Finish MSL Peak Temp (3)
LP2950-30KVUR PREVIEW PFM KVU 3 2500 TBD Call TI Call TI
LP2950-30LP ACTIVE TO-92 LP 3 1000 Pb-Free
(RoHS) CU SN N / A for Pkg Type
LP2950-30LPR ACTIVE TO-92 LP 3 2000 Pb-Free
(RoHS) CU SN N / A for Pkg Type
LP2950-33KVUR PREVIEW PFM KVU 3 2500 TBD Call TI Call TI
LP2950-33LPE3 ACTIVE TO-92 LP 3 1000 Pb-Free
(RoHS) CU SN N / A for Pkg Type
LP2950-33LPRE3 ACTIVE TO-92 LP 3 2000 Pb-Free
(RoHS) CU SN N / A for Pkg Type
LP2950-50KVUR PREVIEW PFM KVU 3 2500 TBD Call TI Call TI
LP2950-50LPRE3 ACTIVE TO-92 LP 3 2000 Pb-Free
(RoHS) CU SN N / A for Pkg Type
LP2951-30D ACTIVE SOIC D 8 75 Green (RoHS &
no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
LP2951-30DG4 ACTIVE SOIC D 8 75 Green (RoHS &
no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
LP2951-30DR ACTIVE SOIC D 8 2500 Green (RoHS &
no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
LP2951-30DRG4 ACTIVE SOIC D 8 2500 Green (RoHS &
no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
LP2951-30DRGR PREVIEW SON DRG 8 1000 TBD Call TI Call TI
LP2951-33D ACTIVE SOIC D 8 75 Green (RoHS &
no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
LP2951-33DG4 ACTIVE SOIC D 8 75 Green (RoHS &
no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
LP2951-33DR ACTIVE SOIC D 8 2500 Green (RoHS &
no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
LP2951-33DRG4 ACTIVE SOIC D 8 2500 Green (RoHS &
no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
LP2951-33DRGR PREVIEW SON DRG 8 1000 TBD Call TI Call TI
LP2951-50D ACTIVE SOIC D 8 75 Green (RoHS &
no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
LP2951-50DG4 ACTIVE SOIC D 8 75 Green (RoHS &
no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
LP2951-50DGK PREVIEW MSOP DGK 8 100 TBD Call TI Call TI
LP2951-50DGKR PREVIEW MSOP DGK 8 2500 TBD Call TI Call TI
LP2951-50DR ACTIVE SOIC D 8 2500 Green (RoHS &
no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
LP2951-50DRG4 ACTIVE SOIC D 8 2500 Green (RoHS &
no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
LP2951-50DRGR PREVIEW SON DRG 8 1000 TBD Call TI Call TI
LP2951-50DRJR PREVIEW SON DRJ 8 1000 TBD Call TI Call TI
LP2951-50P PREVIEW PDIP P 8 50 TBD Call TI Call TI
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
PACKAGE OPTION ADDENDUM
www.ti.com 17-Oct-2006
Addendum-Page 1
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in
a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check
http://www.ti.com/productcontent for the latest availability information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements
for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered
at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and
package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS
compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame
retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material)
(3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder
temperature.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is
provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the
accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take
reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on
incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited
information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI
to Customer on an annual basis.
PACKAGE OPTION ADDENDUM
www.ti.com 17-Oct-2006
Addendum-Page 2
MECHANICAL DATA
MPDI001A – JANUARY 1995 – REVISED JUNE 1999
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
P (R-PDIP-T8) PLASTIC DUAL-IN-LINE
8
4
0.015 (0,38)
Gage Plane
0.325 (8,26)
0.300 (7,62)
0.010 (0,25) NOM
MAX
0.430 (10,92)
4040082/D 05/98
0.200 (5,08) MAX
0.125 (3,18) MIN
5
0.355 (9,02)
0.020 (0,51) MIN
0.070 (1,78) MAX
0.240 (6,10)
0.260 (6,60)
0.400 (10,60)
1
0.015 (0,38)
0.021 (0,53)
Seating Plane
M
0.010 (0,25)
0.100 (2,54)
NOTES: A. All linear dimensions are in inches (millimeters).
B. This drawing is subject to change without notice.
C. Falls within JEDEC MS-001
For the latest package information, go to http://www.ti.com/sc/docs/package/pkg_info.htm
MECHANICAL DATA
MSOT002A – OCTOBER 1994 – REVISED NOVEMBER 2001
1
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
LP (O-PBCY-W3) PLASTIC CYLINDRICAL PACKAGE
4040001-2/C 10/01
STRAIGHT LEAD OPTION
0.016 (0,41)
0.014 (0,35)
0.157 (4,00) MAX
FORMED LEAD OPTION
0.104 (2,65)
0.210 (5,34)
0.170 (4,32)
0.050 (1,27)
0.016 (0,41)
0.022 (0,56)
0.500 (12,70) MIN
Seating
Plane
0.175 (4,44)
0.205 (5,21) 0.165 (4,19)
0.125 (3,17)
DIA
D
C
0.105 (2,67)
0.095 (2,41)
0.135 (3,43) MIN
0.080 (2,03)
0.055 (1,40)
0.045 (1,14)
1
0.105 (2,67)
23
0.080 (2,03)
0.105 (2,67)
NOTES: A. All linear dimensions are in inches (millimeters).
B. This drawing is subject to change without notice.
C. Lead dimensions are not controlled within this area
D. FAlls within JEDEC TO -226 Variation AA (TO-226 replaces TO-92)
E. Shipping Method:
Straight lead option available in bulk pack only.
Formed lead option available in tape & reel or ammo pack.
MECHANICAL DATA
MSOT002A OCTOBER 1994 REVISED NOVEMBER 2001
2POST OFFICE BOX 655303 DALLAS, TEXAS 75265
LP (O-PBCY-W3) PLASTIC CYLINDRICAL PACKAGE
4040001-3/C 10/01
0.094 (2,40)
0.114 (2,90)
0.460 (11,70)
0.539 (13,70)
TAPE & REEL
0.335 (8,50)
0.384 (9,75)
0.020 (0,50) MIN
0.217 (5,50)
0.748 (19,00) 0.748 (19,00)
0.689 (17,50)
0.098 (2,50)
0.433 (11,00)
0.335 (8,50)
0.610 (15,50)
0.650 (16,50)
1.260 (32,00)
0.905 (23,00)
0.234 (5,95)
0.266 (6,75)
0.512 (13,00)
0.488 (12,40)
0.114 (2,90)
0.094 (2,40) 0.146 (3,70)
0.169 (4,30) DIA
NOTES: A. All linear dimensions are in inches (millimeters).
B. This drawing is subject to change without notice.
C. Tape and Reel information for the Format Lead Option package.
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