LP2954/LP2954A
5V and Adjustable Micropower Low-Dropout Voltage
Regulators
General Description
The LP2954 is a 5V micropower voltage regulator with very
low quiescent current (90 A typical at 1 mA load) and very
low dropout voltage (typically 60 mV at light loads and
470 mV at 250 mA load current).
The quiescent current increases only slightly at dropout
(120 A typical), which prolongs battery life.
The LP2954 with a fixed 5V output is available in the
three-lead TO-220 and TO-263 packages. The adjustable
LP2954 is provided in an 8-lead surface mount, small outline
package. The adjustable version also provides a resistor net-
work which can be pin strapped to set the output to 5V.
Reverse battery protection is provided.
The tight line and load regulation (0.04% typical), as well as
very low output temperature coefficient make the LP2954
well suited for use as a low-power voltage reference.
Output accuracy is guaranteed at both room temperature
and over the entire operating temperature range.
Features
n
5V output within 1.2% over temperature (A grade)
n
Adjustable 1.23 to 29V output voltage available
(LP2954IM and LP2954AIM)
n
Guaranteed 250 mA output current
n
Extremely low quiescent current
n
Low dropout voltage
n
Reverse battery protection
n
Extremely tight line and load regulation
n
Very low temperature coefficient
n
Current and thermal limiting
n
Pin compatible with LM2940 and LM340 (5V version
only)
n
Adjustable version adds error flag to warn of output drop
and a logic-controlled shutdown
Applications
n
High-efficiency linear regulator
n
Low dropout battery-powered regulator
Package Outline and Ordering Information
TO-220 3Lead Plastic Package
DS011128-2
Front View
Order Number LP2954AIT or LP2954IT
See NS Package T03B
SO-8 Small Outline Surface Mount
DS011128-33
Top View
Order Number LP2954AIM or LP2954IM
See NS Package M08A
June 1999
LP2954/LP2954A
5V
and
Adjustable
Micropower
Low-Dropout
V
oltage
Regulators
1999 National Semiconductor Corporation
DS011128
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Package Outline and Ordering Information
(Continued)
Ordering Information
Order Number
Temp. Range
Package
NS Package
(T
J
) C
(JEDEC)
Number
LP2954AIT
-40 to +125
TO-220
TO3B
LP2954IT
LP2954AIS
-40 to +125
TO-263
TS3B
LP2954IS
LP2954AIM
-40 to +125
SO-8
M08A
LP2954IM
TO-263 3-Lead Plastic Surface-Mount Package
DS011128-9
Top View
DS011128-10
Side View
Order Number LP2954AIS or LP2954IS
See NS Package TS3B
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2
Absolute Maximum Ratings
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Operating Junction Temperature
Range
LP2954AI/LP2954I
-40C to +125C
Storage Temperature Range
-65C to +150C
Lead Temperature
(Soldering, 5 seconds)
260C
Power Dissipation (Note 2)
Internally Limited
Input Supply Voltage
-20V to +30V
ESD Rating
2 kV
Electrical Characteristics
Limits in standard typeface are for T
J
= 25C, bold typeface applies over the -40C to +125C temperature range. Limits
are guaranteed by production testing or correlation techniques using standard Statistical Quality Control (SQC) methods. Un-
less otherwise noted: V
IN
= 6V, I
L
= 1 mA, C
L
= 2.2 F.
Symbol
Parameter
Conditions
Typical
2954AI
2954I
Units
Min
Max
Min
Max
V
O
Output Voltage
5.0
4.975
5.025
4.950
5.050
V
4.940
5.060
4.900
5.100
1 mA
I
L
250 mA
5.0
4.930
5.070
4.880
5.120
Output Voltage
(Note 3)
20
100
150
ppm/C
Temp. Coefficient
Line Regulation
V
IN
= 6V to 30V
0.03
0.10
0.20
%
0.20
0.40
Load Regulation
I
L
= 1 to 250 mA
0.16
0.20
I
L
= 0.1 to 1 mA
0.04
0.20
0.30
%
(Note 4)
V
IN
V
O
Dropout Voltage
I
L
= 1 mA
60
100
100
mV
(Note 5)
150
150
I
L
= 50 mA
240
300
300
420
420
I
L
= 100 mA
310
400
400
520
520
I
L
= 250 mA
470
600
600
800
800
I
GND
Ground Pin Current
I
L
= 1 mA
90
150
150
A
(Note 6)
180
180
I
L
= 50 mA
1.1
2
2
mA
2.5
2.5
I
L
= 100 mA
4.5
6
6
8
8
I
L
= 250 mA
21
28
28
33
33
I
GND
Ground Pin
V
IN
= 4.5V
170
170
Current at Dropout
120
210
210
A
(Note 6)
I
LIMIT
Current Limit
V
OUT
= 0V
380
500
500
mA
530
530
Thermal Regulation
(Note 7)
0.05
0.2
0.2
%/W
e
n
Output Noise
C
L
= 2.2 F
400
V RMS
Voltage
(10 Hz to 100 kHz)
C
L
= 33 F
260
I
L
= 100 mA
C
L
=33F(Note 9)
80
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3
Electrical Characteristics
(Continued)
Limits in standard typeface are for T
J
= 25C, bold typeface applies over the -40C to +125C temperature range. Limits
are guaranteed by production testing or correlation techniques using standard Statistical Quality Control (SQC) methods. Un-
less otherwise noted: V
IN
= 6V, I
L
= 1 mA, C
L
= 2.2 F.
Symbol
Parameter
Conditions
Typical
2954AI
2954I
Units
Min
Max
Min
Max
Additional Specifications for the Adjustable Device (LP2954AIM and LP2954IM)
V
REF
Reference Voltage
(Note 10)
1.230
1.215
1.205
1.245
1.255
1.205
1.190
1.255
1.270
V
V
REF
/
V
REF
Reference Voltage
Line Regulation
V
IN
=2.5V to
VO(NOM)+1V
0.03
0.1
0.2
V
IN
=2.5V to
VO(NOM)+1V to 30V
(Note 11)
0.2
0.4
V
REF
/
T
Reference Voltage
Temperature
Coefficient
(Note 3)
20
ppm/C
I
B
(FB)
Feedback Pin Bias
Current
20
40
60
40
60
nA
I
GND
Ground Pin Current
at Shutdown (Note
6)
V
SHUTDOWN
1.1V
105
140
140
A
I
O
(SINK)
Output
OFF
Pulldown Current
(Note 12)
30
20
30
20
mA
Dropout Detection Comparator
I
OH
Output
HIGH
Leakage Current
V
OH
=30V
0.01
1
2
1
2
A
V
OL
Output
LOW
Voltage
V
IN
=V
O
(NOM)-0.5V
I
O
(COMP)=400A
150
250
400
250
400
mV
V
THR
(MAX)
Upper Threshold
Voltage
(Note 13)
-60
-80
-95
-35
-25
-80
-95
-35
-25
mV
V
THR
(MIN)
Lower Threshold
Voltage
(Note 13)
-85
-110
-160
-55
-40
-110
-160
-55
-40
mV
HYST
Hysteresis
(Note 13)
15
mV
Shutdown Input
V
OS
Input Offset Voltage
(Referred to V
REF
)
3
-7.5
-10
7.5
10
-7.5
-10
7.5
10
mV
HYST
Hysteresis
6
mV
I
B
Input Bias Current
V
IN
(S/D)=0V to 5V
10
-30
-50
30
50
-30
-50
30
50
nA
Note 1: Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the de-
vice outside of its rated operating conditions.
Note 2: The maximum allowable power dissipation is a function of the maximum junction temperature, T
J
(MAX), the junction-to-ambient thermal resistance,
J-A
,
and the ambient temperature, T
A
. The maximum allowable power dissipation at any ambient temperature is calculated using:
.
Exceeding the maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. The junction-to-ambient
thermal resistance of the TO-220 (without heatsink) is 60C/W, 73C/W for the TO-263, and 160C/W for the SO-8. If the TO-263 package is used, the thermal re-
sistance can be reduced by increasing the P.C. board copper area thermally connected to the package: Using 0.5 square inches of copper area,
JA
is 50C/W; with
1 square inch of copper area,
JA
is 37C/W; and with 1.6 or more square inches of copper area,
JA
is 32C/W. The junction-to-case thermal resistance is 3C/W.
If an external heatsink is used, the effective junction-to-ambient thermal resistance is the sum of the junction-to-case resistance (3C/W), the specified thermal re-
sistance of the heatsink selected, and the thermal resistance of the interface between the heatsink and the LP2954. Some typical values are listed for interface ma-
terials used with TO-220:
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4
Electrical Characteristics
(Continued)
TABLE 1. Typical Values of Case-to-Heatsink
Thermal Resistance (C/W) (Data from AAVID Eng.)
Silicone grease
1.0
Dry interface
1.3
Mica with grease
1.4
TABLE 2. Typical Values of Case-to-Heatsink
Thermal Resistance (C/W) (Data from Thermalloy)
Thermasil III
1.3
Thermasil II
1.5
Thermalfilm (0.002) with grease
2.2
Note 3: Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
Note 4: Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested separately for load regulation in the load
ranges 0.1 mA1 mA and 1 mA250 mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification.
Note 5: Dropout voltage is defined as the input to output differential at which the output voltage drops 100 mV below the value measured with a 1V differential.
Note 6: Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the load current plus the ground pin current.
Note 7: 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 200 mA load pulse at V
IN
= 20V (3W pulse) for T = 10 ms.
Note 8: When used in dual-supply systems where the regulator load is returned to a negative supply, the output voltage must be diode-clamped to ground.
Note 9: Connect a 0.1F capacitor from the output to the feedback pin.
Note 10: V
REF
V
OUT
(V
IN
-1V), 2.3V
V
IN
30V, 100A
I
L
250mA.
Note 11: Two seperate tests are performed, one covering V
IN
=2.5V to V
O
(NOM)+1V and the other test for V
IN
=2.5V to V
O
(NOM)+1V to 30V.
Note 12: V
SHUTDOWN
1.1V, VOUT=V
O
(NOM).
Note 13: Comparator thresholds are expressed in terms of a voltage differential at the Feedback terminal below the nominal reference voltage measured at
V
IN
=V
O
(NOM)+1V. To express these thresholds in terms of output voltage change, multiply by the Error amplifier gain, which is V
OUT
/V
REF
=(R1+R2)/R2.
Note 14: Human body model, 200pF discharged through 1.5k
.
Typical Performance Characteristics
Quiescent Current
DS011128-12
Quiescent Current
DS011128-13
Ground Pin Current vs Load
DS011128-14
Ground Pin Current
DS011128-15
Ground Pin Current
DS011128-16
Output Noise Voltage
DS011128-17
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