LP2952/LP2952A/LP2953/LP2953A
Adjustable Micropower Low-Dropout Voltage Regulators
General Description
The LP2952 and LP2953 are micropower voltage regulators
with very low quiescent current (130 µA typical at 1 mA load)
and very low dropout voltage (typ. 60 mV at light load and
470 mV at 250 mA load current). They are ideally suited for
battery-powered systems. Furthermore, the quiescent cur-
rent increases only slightly at dropout, which prolongs bat-
tery life.
The LP2952 and LP2953 retain all the desirable characteris-
tics of the LP2951, but offer increased output current, addi-
tional features, and an improved shutdown function.
The internal crowbar pulls the output down quickly when the
shutdown is activated.
The error flag goes low if the output voltage drops out of
regulation.
Reverse battery protection is provided.
The internal voltage reference is made available for external
use, providing a low-T.C. reference with very good line and
load regulation.
The parts are available in DIP and surface mount packages.
Features
n
Output voltage adjusts from 1.23V to 29V
n
Guaranteed 250 mA output current
n
Extremely low quiescent current
n
Low dropout voltage
n
Extremely tight line and load regulation
n
Very low temperature coefficient
n
Current and thermal limiting
n
Reverse battery protection
n
50 mA (typical) output pulldown crowbar
n
5V and 3.3V versions available
LP2953 Versions Only
n
Auxiliary comparator included with CMOS/TTL
compatible output levels. Can be used for fault
detection, low input line detection, etc.
Applications
n
High-efficiency linear regulator
n
Regulator with under-voltage shutdown
n
Low dropout battery-powered regulator
n
Snap-ON/Snap-OFF regulator
Block Diagrams
LP2952
DS011127-1
LP2953
DS011127-2
May 1999
LP2952/LP2952A/LP2953/LP2953A
Adjustable
Micropower
Low-Dropout
V
oltage
Regulators
© 1999 National Semiconductor Corporation
DS011127
www.national.com
Pinout Drawings
Ordering Information
LP2952
Order
Number
Temp.
Range
(T
J
) ˚C
Package
NSC
Drawing
Number
LP2952IN,
LP2952AIN,
LP2952IN-3.3,
LP2952AIN-3.3
−40 to
+125
14-Pin
Molded
DIP
N14A
LP2952IM,
LP2952AIM,
LP2952IM-3.3,
LP2952AIM-3.3
−40 to
+125
16-Pin
Surface
Mount
M16A
LP2953
Order
Number
Temp.
Range
(T
J
) ˚C
Package
NSC
Drawing
Number
LP2953IN,
LP2953AIN,
LP2953IN-3.3,
LP2953AIN-3.3
−40 to
+125
16-Pin
Molded DIP
N16A
LP2953IM,
LP2953AIM,
LP2953IM-3.3,
LP2953AIM-3.3
−40 to
+125
16-Pin
Surface
Mount
M16A
LP2953AMJ/883
5962-9233601MEA
LP2953AMJ-QMLV
5962-9233601VEA
−55 to
+150
16-Pin
Ceramic
DIP
J16A
LP2953AMWG/883
5962-9233601QXA
LP2953AMWG-QMLV
5962-9233601VXA
−55 to
+150
16-Pin
Ceramic
Surface
Mount
WG16A
LP2952
14-Pin DIP
DS011127-11
LP2953
16-Pin DIP
DS011127-13
LP2952
16-Pin SO
DS011127-12
LP2953
16-Pin SO
DS011127-14
www.national.com
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.
Storage Temperature Range
−65˚C
≤
T
A
≤
+150˚C
Operating Temperature Range
LP2952I, LP2953I, LP2952AI,
LP2953AI, LP2952I-3.3,
LP2953I-3.3, LP2952AI-3.3,
LP2953AI-3.3
−40˚C
≤
T
J
≤
+125˚C
LP2953AM
−55˚C
≤
T
A
≤
+125˚C
Lead Temp. (Soldering, 5 seconds)
260˚C
Power Dissipation (Note 2)
Internally Limited
Maximum Junction Temperature
LP2952I, LP2953I, LP2952AI,
LP2953AI, LP2952I-3.3,
LP2953I-3.3, LP2952AI-3.3,
LP2953AI-3.3
+125˚C
LP2953AM
+150˚C
Input Supply Voltage
−20V to +30V
Feedback Input Voltage (Note 3)
−0.3V to +5V
Comparator Input Voltage (Note 4)
−0.3V to +30V
Shutdown Input Voltage (Note 4)
−0.3V to +30V
Comparator Output Voltage (Note 4)
−0.3V to +30V
ESD Rating (Note 15)
2 kV
Electrical Characteristics
Limits in standard typeface are for T
J
= 25˚C, bold typeface applies over the full
operating temperature range. Limits are guaranteed by production testing or correlation techniques using standard Statistical
Quality Control (SQC) methods. Unless otherwise specified: V
IN
= V
O
(NOM) + 1V, I
L
= 1 mA, C
L
= 2.2 µF for 5V parts and
4.7µF for 3.3V parts. Feedback pin is tied to V Tap pin, Output pin is tied to Output Sense pin.
3.3V Versions
Symbol
Parameter
Conditions
Typical
LP2952AI-3.3, LP2953AI-3.3
LP2952I-3.3, LP2953I-3.3
Units
Min
Max
Min
Max
V
O
Output Voltage
3.3
3.284
3.317
3.267
3.333
V
3.260
3.340
3.234
3.366
1 mA
≤
I
L
≤
250 mA
3.3
3.254
3.346
3.221
3.379
5V Versions
Symbol
Parameter
Conditions
Typical
LP2952AI, LP2953AI,
LP2952I, LP2953I
Units
LP2953AM (Note 17)
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
All Voltage Options
Electrical Characteristics
Limits in standard typeface are for T
J
= 25˚C, bold typeface applies over the full operating temperature range. Limits are guar-
anteed by production testing or correlation techniques using standard Statistical Quality Control (SQC) methods. Unless other-
wise specified: V
IN
= V
O
(NOM) + 1V, I
L
= 1 mA, C
L
= 2.2 µF for 5V parts and 4.7µF for 3.3V parts. Feedback pin is tied to V
Tap pin, Output pin is tied to Output Sense pin.
Symbol
Parameter
Conditions
Typical
LP2952AI,
LP2953AI,
LP2952AI-3.3,
LP2953AI-3.3,
LP2953AM
(Notes 16, 17)
LP2952I, LP2953I,
LP2952I-3.3,
LP2953I-3.3
Units
Min
Max
Min
Max
REGULATOR
Output Voltage Temp.
Coefficient
(Note 5)
20
100
150
ppm/˚C
Output Voltage Line
Regulation
V
IN
= V
O
(NOM) + 1V to 30V
0.03
0.1
0.2
%
0.2
0.4
Output Voltage Load
Regulation (Note 6)
I
L
= 1 mA to 250 mA
0.04
0.16
0.20
%
I
L
= 0.1 mA to 1 mA
0.20
0.30
www.national.com
3
Electrical Characteristics
(Continued)
Limits in standard typeface are for T
J
= 25˚C, bold typeface applies over the full operating temperature range. Limits are guar-
anteed by production testing or correlation techniques using standard Statistical Quality Control (SQC) methods. Unless other-
wise specified: V
IN
= V
O
(NOM) + 1V, I
L
= 1 mA, C
L
= 2.2 µF for 5V parts and 4.7µF for 3.3V parts. Feedback pin is tied to V
Tap pin, Output pin is tied to Output Sense pin.
Symbol
Parameter
Conditions
Typical
LP2952AI,
LP2953AI,
LP2952AI-3.3,
LP2953AI-3.3,
LP2953AM
(Notes 16, 17)
LP2952I, LP2953I,
LP2952I-3.3,
LP2953I-3.3
Units
Min
Max
Min
Max
REGULATOR
V
IN
–V
O
Dropout Voltage
(Note 7)
I
L
= 1 mA
60
100
100
mV
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
(Note 8)
I
L
= 1 mA
130
170
170
µA
200
200
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 Current at
Dropout
V
IN
= V
O
(NOM) −0.5V
165
210
210
µA
I
L
= 100 µA
240
240
I
GND
Ground Pin Current at
Shutdown (Note 8)
V
SHUTDOWN
≤
1.1V
105
140
140
µA
I
LIMIT
Current Limit
V
OUT
= 0
380
500
500
mA
530
530
Thermal Regulation
(Note 10)
0.05
0.2
0.2
%/W
e
n
Output Noise Voltage
(10 Hz to 100 kHz)
I
L
= 100 mA
C
L
= 4.7 µF
400
µV
RMS
C
L
= 33 µF
260
C
L
= 33 µF (Note 11)
80
V
REF
Reference Voltage
(Note 12)
1.230
1.215
1.245
1.205
1.255
V
1.205
1.255
1.190
1.270
Reference Voltage
Line Regulation
V
IN
= 2.5V to V
O
(NOM) + 1V
0.03
0.1
0.2
%
V
IN
= V
O
(NOM) + 1V to 30V
(Note 13)
0.2
0.4
Reference Voltage
Load Regulation
I
REF
= 0 to 200 µA
0.25
0.4
0.8
%
0.6
1.0
Reference Voltage
Temp. Coefficient
(Note 5)
20
ppm/˚C
I
B
(FB)
Feedback Pin Bias
Current
20
40
40
nA
60
60
I
O
(SINK)
Output “OFF” Pulldown
Current
(Note 9)
30
30
mA
20
20
www.national.com
4
Electrical Characteristics
(Continued)
Limits in standard typeface are for T
J
= 25˚C, bold typeface applies over the full operating temperature range. Limits are guar-
anteed by production testing or correlation techniques using standard Statistical Quality Control (SQC) methods. Unless other-
wise specified: V
IN
= V
O
(NOM) + 1V, I
L
= 1 mA, C
L
= 2.2 µF for 5V parts and 4.7µF for 3.3V parts. Feedback pin is tied to V
Tap pin, Output pin is tied to Output Sense pin.
Symbol
Parameter
Conditions
Typical
LP2952AI,
LP2953AI,
LP2952AI-3.3,
LP2953AI-3.3,
LP2953AM
(Notes 16, 17)
LP2952I, LP2953I,
LP2952I-3.3,
LP2953I-3.3
Units
Min
Max
Min
Max
DROPOUT DETECTION COMPARATOR
I
OH
Output “HIGH”
Leakage
V
OH
= 30V
0.01
1
1
µA
2
2
V
OL
Output “LOW” Voltage
V
IN
= V
O
(NOM) − 0.5V
I
O
(COMP) = 400 µA
150
250
250
mV
400
400
V
THR
(MAX)
Upper Threshold
Voltage
(Note 14)
−60
−80
−35
−80
−35
mV
−95
−25
−95
−25
V
THR
(MIN)
Lower Threshold
Voltage
(Note 14)
−85
−110
−55
−110
−55
mV
−160
−40
−160
−40
HYST
Hysteresis
(Note 14)
15
mV
SHUTDOWN INPUT (Note 15)
V
OS
Input Offset
(Referred to V
REF
)
±
3
−7.5
7.5
−7.5
7.5
mV
Voltage
−10
10
−10
10
HYST
Hysteresis
6
mV
I
B
Input Bias
V
IN
(S/D) = 0V to 5V
10
−30
30
−30
−50
−30
50
nA
Current
−50
50
LP2953AM
10
−30
30
−75
75
AUXILIARY COMPARATOR (LP2953 Only)
V
OS
Input Offset Voltage
(Referred to V
REF
)
±
3
−7.5
7.5
−7.5
−10
7.5
10
mV
−10
10
LP2953AM
±
3
−7.5
7.5
−12
12
HYST
Hysteresis
6
mV
I
B
Input Bias Current
V
IN
(COMP) = 0V to 5V
10
−30
30
−30
−50
30
50
nA
−50
50
LP2953AM
10
−30
30
−75
75
I
OH
Output “HIGH”
Leakage
V
OH
= 30V
0.01
1
1
2
µA
V
IN
(COMP) = 1.3V
2
LP2953AM
0.01
1
2.2
V
OL
Output “LOW” Voltage
V
IN
(COMP) = 1.1V
150
250
250
400
mV
I
O
(COMP) = 400 µA
400
LP2953AM
150
250
420
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,
θ
J–A
,
and the ambient temperature, T
A
. The maximum allowable power dissipation at any ambient temperature is calculated using the equation for P(MAX),
.
www.national.com
5
Electrical Characteristics
(Continued)
Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. See APPLICATION
HINTS for additional information on heatsinking and thermal resistance.
Note 3: 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 4: May exceed the input supply voltage.
Note 5: Output or reference voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
Note 6: Load regulation is measured at constant junction temperature using low duty cycle pulse testing. Two separate tests are performed, one for the range of 100
µA to 1 mA and one for the 1 mA to 250 mA range. Changes in output voltage due to heating effects are covered by the thermal regulation specification.
Note 7: 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. At
very low values of programmed output voltage, the input voltage minimum of 2V (2.3V over temperature) must be observed.
Note 8: Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the ground pin current, output load current, and
current through the external resistive divider (if used).
Note 9: V
SHUTDOWN
≤
1.1V, V
OUT
= V
O
(NOM).
Note 10: Thermal regulation is the change in output voltage at a time T after a change in power dissipation, excluding load or line regulation effects. Specifications
are for a 200 mA load pulse at V
IN
= V
O
(NOM)+15V (3W pulse) for T = 10 ms.
Note 11: Connect a 0.1 µF capacitor from the output to the feedback pin.
Note 12: V
REF
≤
V
OUT
≤
(V
IN
− 1V), 2.3V
≤
V
IN
≤
30V, 100 µA
≤
I
L
≤
250 mA.
Note 13: Two separate tests are performed, one covering 2.5V
≤
V
IN
≤
V
O
(NOM)+1V and the other test for V
O
(NOM)+1V
≤
V
IN
≤
30V.
Note 14: 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
(refer to
Figure 4).
Note 15: Human body model, 200 pF discharged through 1.5 k
Ω
.
Note 16: Drive Shutdown pin with TTL or CMOS-low level to shut regulator OFF, high level to turn regulator ON.
Note 17: A military RETS specification is available upon request. For more information on military products, please refer to the Mil-Aero web page at
http://www.national.com/appinfo/milaero/index.html.
Typical Performance Characteristics
Unless otherwise specified: V
IN
= 6V, I
L
= 1 mA, C
L
= 2.2 µF,
V
SD
= 3V, T
A
= 25˚C, V
OUT
= 5V.
Quiescent Current
DS011127-27
Quiescent Current
DS011127-28
Ground Pin Current vs Load
DS011127-29
Ground Pin Current
DS011127-30
Ground Pin Current
DS011127-31
Output Noise Voltage
DS011127-32
www.national.com
6
Typical Performance Characteristics
Unless otherwise specified: V
IN
= 6V, I
L
= 1 mA, C
L
= 2.2 µF,
V
SD
= 3V, T
A
= 25˚C, V
OUT
= 5V. (Continued)
Ripple Rejection
DS011127-33
Ripple Rejection
DS011127-34
Ripple Rejection
DS011127-35
Line Transient Response
DS011127-36
Line Transient Response
DS011127-37
Output Impedance
DS011127-38
Load Transient Response
DS011127-39
Load Transient Response
DS011127-40
Dropout Characteristics
DS011127-41
Enable Transient
DS011127-42
Enable Transient
DS011127-43
Short-Circuit Output Current
and Maximum Output Current
DS011127-44
www.national.com
7
Typical Performance Characteristics
Unless otherwise specified: V
IN
= 6V, I
L
= 1 mA, C
L
= 2.2 µF,
V
SD
= 3V, T
A
= 25˚C, V
OUT
= 5V. (Continued)
Feedback Bias Current
DS011127-45
Feedback Pin Current
DS011127-46
Error Output
DS011127-47
Comparator Sink Current
DS011127-48
Divider Resistance
DS011127-49
Dropout Detection
Comparator Threshold
Voltages
DS011127-50
Thermal Regulation
DS011127-51
Minimum Operating Voltage
DS011127-52
Dropout Voltage
DS011127-53
www.national.com
8
Schematic Diagram
Application Hints
HEATSINK REQUIREMENTS (Industrial Temperature
Range Devices)
The maximum allowable power dissipation for the LP2952/
LP2953 is limited by the maximum junction temperature
(+125˚C) and the external factors that determine how quickly
heat flows away from the part: the
ambient temperature and
the
junction-to-ambient thermal resistance for the specific
application.
The industrial temperature range (−40˚C
≤
T
J
≤
+125˚C)
parts are manufactured in plastic DIP and surface mount
packages which contain a copper lead frame that allows
heat to be effectively conducted away from the die, through
the ground pins of the IC, and into the copper of the PC
board. Details on heatsinking using PC board copper are
covered later.
To determine if a heatsink is required, the maximum power
dissipated by the regulator, P(max), must be calculated. It is
important to remember that if the regulator is powered from
a transformer connected to the AC line, the maximum
specified AC input voltage must be used (since this pro-
duces the maximum DC input voltage to the regulator).
Fig-
ure 1 shows the voltages and currents which are present in
the circuit. The formula for calculating the power dissipated
in the regulator is also shown in
Figure 1:
DS011127-6
www.national.com
9
Application Hints
(Continued)
The next parameter which must be calculated is the maxi-
mum allowable temperature rise, T
R
(max). This is calculated
by using the formula:
T
R
(max) = T
J
(max) − T
A
(max)
θ
(J–A)
= T
R
(max)/P(max)
where: T
J
(max) is the maximum allowable junction tem-
perature
T
A
(max) is the maximum ambient temperature
Using the calculated values for T
R
(max) and P(max), the re-
quired value for junction-to-ambient thermal resistance,
θ
(J–A)
, can now be found:
The heatsink is made using the PC board copper. The heat
is conducted from the die, through the lead frame (inside the
part), and out the pins which are soldered to the PC board.
The pins used for heat conduction are given in
Table 1.
TABLE 1. Heat Conducting Pins
Part
Package
Pins
LP2952IN, LP2952AIN,
14-Pin DIP
3, 4, 5,
LP2952IN-3.3,
LP2952AIN-3.3
10, 11, 12
LP2953IN, LP2953AIN,
16-Pin DIP
4, 5, 12, 13
LP2953IN-3.3,
LP2953AIN-3.3
LP2952IM, LP2952AIM,
16-Pin
Surface
Mount
1, 8, 9, 16