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DATA SHEET
LND2950 / LND2951
100mA Low Dropout Voltage Regulators
GENERAL DESCRIPTION
The LND2950-XX is a low power voltage
regulator.This device is an excellent choice for use in
battery powered application such as cordless
telephone, radio control systems, and portable
computers.
The LND2950-XX/LND2951-XX features very low
quiescent current (75µA Typ.) and very low drop
output voltage (Typ. 40mV at light load and 380mV at
100mA).This includes a tight initial tolerance of 0.5%
typ., extremely good load and line regulation of
0.05% typ., and very low output temperature
coefficient, making the LND2950-XX/LND2951-XX
useful as a low-power voltage reference.
The error flag output feature is used as power-on
reset, warning of a low output voltage, due to falling
battery voltage on input. Another feature is the logic-
compatible shutdown input, which enables the
regulator to be switched on and off.
8 dip
The LND2951-XX is available in 8 pin plastic
packages. The regulator output voltage may be pin-
strapped for a –XX voltage or programmed from 1.24
volts to 29 volts with an external pair of resistors.
The LND2950-XX is offered in a 3-pin TO-92
package compatible with other fixed regulators.
FEATURES
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High accuracy output voltage
Guaranteed 100mA output
Very low quiescent current
Low dropout voltage
Extremely tight load and line regulation
Very low temperature coefficient
Needs only 1µF for stability
Error Flag warns of output dropout
Logic-Controlled electronic shutdown
Output programmable from 1.24 to 29V
APPLICATIONS
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Battery powered systems
Cordless telephones
Radio control systems
Portable/Palm Top/ notebook
computers
Portable Instrumentation
Avionics
Automotive Electronics
SMPS Post-Regulator
Voltage Reference
DEVICE SELECTION GUIDE
V
OUT
, Volts
2.85*
3.0
3.3
5.0
Device
LND2950-2.85,LND2951-2.85
LND2950-3.0,LND2951-3.0
LND2950-3.3, LND2951-3.3
LND2950-5.0, LND2951-5.0
*Other versions are also available
Vout=2.0V TO 5.0V. Please consult for more
information
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Linear Dimensions, Inc.
•
445 East Ohio Street, Chicago IL 60611 USA
•
tel 312.321.1810
•
fax 312.321.1830
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www.lineardimensions.com
•
LND2950 / LND2951
ABSOLUTE MAXIMUM RATING
Power Dissipation
Lead Temperature (Soldering, 5 seconds)
Storage Temperature Range
Operating Junction Temperature Range
Input Supply Voltage
Feedback Input Voltage
Shutdown Input Voltage
Error Comparator Output
Internally Limited
260º
-65ºC to+150ºC
-55ºC to +150º
-0.3 to+30V
-1.5 to+30V
-0.3 to +30V
-0.3 to +30V
PIN CONFIGURATION
Output
Sense
Shutdown
GND
1
2
3
4
8
7
6
5
Input
Feedback
-XX V tap
Error
OUTPUT
GND
INPUT
LND2951-XX
8-Pin Plastic (Top View)
+V
IN
TO-92 (Bottom View)
100k
Ω
ERROR
OUTPUT
5
ERROR
8
VIN
V
OUT
1
V
OUT 1.2
0.01
µ
F
R1
GND
4
FB
7
1.23V
30V
+
3.3
µ
F
LND2951
SHUTDOWN 3
INPUT
Off
On
Note : pins 2 and 6
are left open
V
OUT
= V
(1+ R1/R2)
REF
V
REF
R2
Figure 1: Adjustable Regulator
•
Linear Dimensions, Inc.
•
445 East Ohio Street, Chicago IL 60611 USA
•
tel 312.321.1810
•
fax 312.321.1830
•
www.lineardimensions.com
•
LND2950 / LND2951
ELECTRICAL CHARACTERISTICS
PARAMETER
Output Voltage
Output Voltage
Output Voltage Temperature
Coefficient
Line Regulation(Note 3)
Load Regulation( Note3)
Dropout Voltage(Note 5)
Ground Current
Dropout Ground Current
Current Limit
Thermal regulation
Output Noise,10Hz to
100KHz
8-PIN Versions Only
Reference Voltage
Reference Voltage
Feedback Pin Bias Current
Reference Voltage
Temperature Coefficient
Feedback Pin Bias Current
Temperature Coefficient
Error Comparator
Output Leakage Current
Output Low Voltage
Upper Threshold Voltage
Lower Threshold Voltage
Hysteresis
Shutdown Input
Input Logic Voltage
Shut down pin Input Current
(T
A
=25
ºC,
V
IN
=15V Unless otherwise noted)
CONDITIONS (note 2)
-25ºC
≤T
j
≤85ºC
Full Operating Temperature
100µA
≤I
L
≤100mA,
T
J
≤
T
JMAX
(note 1)
V
O
+1V≤V
IN
≤30V(Note
4)
100µA
≤I
L
≤100mA
I
L=
100µA
I
L=
100mA
I
L=
100µA
I
L=
100mA
V
IN
=V
0
=-0.5V,I
L
=100µA
V
out
=0
C
L
= 1µF
C
L=
200µF
C
L=
3.3µF
(Bypass=0.01µF pins 7 to 1
(LND2951-XX))
MIN
0.985 |Vo|
0.98 |Vo|
0.976 |Vo|
TYP
V
O
V
O
50
0.04
0.1
50
380
75
8
110
160
0.05
430
160
100
MAX
1.015 |Vo|
1.02 |Vo|
1.024 |Vo|
150
0.4
0.3
80
450
120
12
170
200
0.2
UNITS
V
ppm/ºC
%
%
mV
µA
mA
µA
mA
%/W
µV rms
Over temperature(Note 6)
(note 7)
1.21
1.185
1.235
20
50
0.1
1.26
1.285
40
V
nA
ppm/ºC
nA/ºC
Voh=30V
Vin=4.5V,I
OL
=400µA
(note 8)
(note 8)
(note 8)
Low(Regulator ON)
High (Regulator OFF)
V
s
= 2.4V
V
s
=30V
(Note 9)
V
out
=5.0V
3.3V≤V
out
<5.0V
2.0V≤V
out
<3.3V
40
0.01
150
60
75
15
1.3
1.0
250
95
µA
mV
0.7
50
600
10
20
30
2
30
450
3
V
Regulator Output current in
Shutdown
µA
•
Linear Dimensions, Inc.
•
445 East Ohio Street, Chicago IL 60611 USA
•
tel 312.321.1810
•
fax 312.321.1830
•
www.lineardimensions.com
•
LND2950 / LND2951
Note 1: Output or reference voltage temperature coefficients is defined as the worst case voltage change divided by
the total temperature range.
Note 2: Unless otherwise specified all limits guaranteed for T
j
=25ºC, V
in
=V
o
+1V,I
L
=100µAand C
L
=1µF. Additional
conditions for the 8 pin versions are feedback tied to –XX V tap and output tied to output sense(V
out
=XX V) and V
shutdown
≤0.8
V.
Note 3: Regulations 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 4: Line regulation for LND2951-xx is tested at 150ºCfor I
L
=1mA. For I
L =
100µA and Tj=125ºC, line regulation is
guaranteed by design to 0.2%. See typical performance characteristics for line regulation verse temperature and load
current.
Note 5: Dropout voltage is defined as the input to output differential at which the output voltage drops 100mV 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: V
ref
≤V
out
≤(Vin-1V),
2.3V
≤Vin ≤
30V,100µA≤I
L
≤
100mA,T
J
≤T
JMAX
Note 7: Output or reference voltage temperature coefficient is defined as the worst case voltage change divided by the
total temperature range.
Note 8: Comparator thresholds are expressed in terms of a voltage differential at the feedback terminal below the
nominal reference voltage measured at V
O
+1V input. To express these thresholds in terms of output voltage change,
multiply by the error amplifier gain =V
out
/V
ref
=(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 95mVx5V/1.235V=384mV. Thresholds remain constant
as a percent of V
out
as V
out
is varied, with the dropout warning occurring at typically 5% below nominal, 7.5%
guaranteed.
Note 9: V
shutdown
≥
2V,Vin
≤30V,V
out
=0, Feed-back pin tied to –XX V tap.
APPLICATION HINTS
External Capacitors
A 1.0
µF
(or greater ) capacitor is required between the output and the ground for stability at output
voltages of 5V or more. At lower output voltages, more capacitance is required. 2.2
µF
or more is
recommended for 3 V and 3.3 V versions.
Programming the Output Voltage
The LND2951 may be pin-strapped for the nominal fixed output voltage. Alternatively it may be
programmed for any output voltage between 1.24 V and 29 V depending upon the requirements.
BLOCK DIAGRAM AND TYPICAL APPLICATIONS
Unregulated DC
+
Unregulated DC
7
FEEDBACK
INPUT
8
1
OUTPUT
2
OUTPUT
Vout
I <= 100mA
L
+
-
ERROR
AMPLIFIER
+
See
Application
Hints
From
CMOS
or
TTL
3
SHUTDOWN
+
+
60 mV
+
1.23 V
Reference
+
Vout
I <= 100mA
L
INPUT
SENSE
+
See
Application
Hints
+
-
6
ERROR
AMPLIFIER
XX VTAP
330k
Ω
5
II
60k
ERROR
-
+
1.23 V
Reference
To
CMOS
or
TTL
4
GROUND
Error detection Comparator
GROUND
•
Linear Dimensions, Inc.
•
445 East Ohio Street, Chicago IL 60611 USA
•
tel 312.321.1810
•
fax 312.321.1830
•
www.lineardimensions.com
•
LND2950 / LND2951
TYPICAL APPLICATIONS
+V
IN
8
ERROR
OUTPUT
5
ERROR
+V
IN
V
OUT
1
*V
OUT
V
IN
5V BUS
+V
IN
OUT
LND29500Z-5.0
V
*V
OUT
5V
+
1
µ
F
LND2951
SHUTDOWN 3
INPUT
GND
4
FB
7
GND
*Minimum input-output voltage ranges from
40mV to 400mV, depending on load current.
Current limit is typically 160mA.
*Minimum input-output voltage ranges from
40mV to 400mV, depending on load current.
Current limit is typically 160mA.
Wide Input Voltage Range Current Limiter
5V Current Limiter
+V=1.2
I
L
+V
IN
8
470k
Ω
V
8
5
470kΩ
ERROR
+V
IN
V
OUT
1
V OUT
F
+
1
µ
R1
FB 7
GND
4
SHUTDOWN 3 SD
INPUT
GND
4
FB
7
R
1%
IN
LOAD
30V
I = 1.23/R
L
1
V
OUT
*V
OUT
LND2951
1
µ
F
LND2951
3 SD
RESET
+
1
µ
F
R2
Latch Off When Error Flag Occurs
Low Drift Current Source
•
Linear Dimensions, Inc.
•
445 East Ohio Street, Chicago IL 60611 USA
•
tel 312.321.1810
•
fax 312.321.1830
•
www.lineardimensions.com
•
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