LND2950 / LND2951
8 dip
GENERAL DESCRIPTION
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 1F for stability
Error Flag warns of output dropout
Logic-Controlled electronic shutdown
Output programmable from 1.24 to 29V
FEATURES
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 (75A 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.
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.
APPLICATIONS
Battery
powered
systems
Cordless
telephones
Radio control systems
Portable/Palm
Top/
notebook
computers
Portable
Instrumentation
Avionics
Automotive
Electronics
SMPS
Post-Regulator
Voltage
Reference
100mA Low Dropout Voltage Regulators
DEVICE SELECTION GUIDE
V
OUT
, Volts
Device
2.85*
LND2950-2.85,LND2951-2.85
3.0
LND2950-3.0,LND2951-3.0
3.3
LND2950-3.3, LND2951-3.3
5.0
LND2950-5.0, LND2951-5.0
*Other versions are also available
Vout=2.0V TO 5.0V. Please consult for more
information
DATA SHEET
Linear Dimensions, Inc. 445 East Ohio Street, Chicago IL 60611 USA tel 312.321.1810 fax 312.321.1830
www.lineardimensions.com
Power Dissipation
Internally Limited
Lead Temperature (Soldering, 5 seconds)
260
Storage Temperature Range
-65C to+150C
Operating Junction Temperature Range
-55C to +150
Input Supply Voltage
-0.3 to+30V
Feedback Input Voltage
-1.5 to+30V
Shutdown Input Voltage
-0.3 to +30V
Error Comparator Output
-0.3 to +30V
ABSOLUTE MAXIMUM RATING
LND2950 / LND2951
PIN CONFIGURATION
Linear Dimensions, Inc. 445 East Ohio Street, Chicago IL 60611 USA tel 312.321.1810 fax 312.321.1830
www.lineardimensions.com
1
2
3
4
5
6
7
8
Output
Sense
Shutdown
GND
Error
-XX V tap
Feedback
Input
LND2951-XX
OUTPUT
GND
INPUT
IN
3
V = V (1+ R1/R2)
OUT
V
3.3 F
R1
1.2 30V
FB
+V
INPUT
0.01 F
ERROR
ERROR
GND
4
SHUTDOWN
R2
OUTPUT
V
IN
5
V
1.23V
OUT
7
Note : pins 2 and 6
are left open
OUT
REF
V
REF
1
8
LND2951
On
Off
+
100k
Figure 1: Adjustable Regulator
TO-92 (Bottom View)
8-Pin Plastic (Top View)
PARAMETER
CONDITIONS (note 2)
MIN
TYP
MAX
UNITS
Output Voltage
-25C
T
j
85C
Full Operating Temperature
0.985 |Vo|
0.98 |Vo|
V
O
1.015 |Vo|
1.02 |Vo|
Output Voltage
100A
I
L
100mA, T
J
T
JMAX
0.976 |Vo|
V
O
1.024 |Vo|
V
Output Voltage Temperature
Coefficient
(note 1)
50
150
ppm/C
Line Regulation(Note 3)
V
O
+1V
V
IN
30V(Note 4)
0.04
0.4
%
Load Regulation( Note3)
100A
I
L
100mA
0.1
0.3
%
Dropout Voltage(Note 5)
I
L=
100A
I
L=
100mA
50
380
80
450
mV
Ground Current
I
L=
100A
I
L=
100mA
75
8
120
12
A
mA
Dropout Ground Current
V
IN
=V
0
=-0.5V,I
L
=100
A
110
170
A
Current Limit
V
out
=0
160
200
mA
Thermal regulation
0.05
0.2
%/W
Output Noise,10Hz to
100KHz
C
L
= 1F
C
L=
200F
C
L=
3.3F
(Bypass=0.01F pins 7 to 1
(LND2951-XX))
430
160
100
V rms
8-PIN Versions Only
Reference Voltage
1.21
1.235
1.26
Reference Voltage
Over temperature(Note 6)
1.185
1.285
V
Feedback Pin Bias Current
20
40
nA
Reference Voltage
Temperature Coefficient
(note 7)
50
ppm/C
Feedback Pin Bias Current
Temperature Coefficient
0.1
nA/C
Error Comparator
Output Leakage Current
Voh=30V
0.01
1.0
A
Output Low Voltage
Vin=4.5V,I
OL
=400A
150
250
Upper Threshold Voltage
(note 8)
40
60
Lower Threshold Voltage
(note 8)
75
95
Hysteresis
(note 8)
15
mV
Shutdown Input
Input Logic Voltage
Low(Regulator ON)
High (Regulator OFF)
2
1.3
0.7
V
Shut down pin Input Current
V
s
= 2.4V
V
s
=30V
30
450
50
600
(Note 9)
V
out
=5.0V
3
10
3.3V
V
out
<5.0V
20
Regulator Output current in
Shutdown
2.0V
V
out
<3.3V
30
A
ELECTRICAL CHARACTERISTICS
(T
A
=25
C, V
IN
=15V Unless otherwise noted)
LND2950 / LND2951
Linear Dimensions, Inc. 445 East Ohio Street, Chicago IL 60611 USA tel 312.321.1810 fax 312.321.1830
www.lineardimensions.com
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
=25C, V
in
=V
o
+1V,I
L
=100Aand C
L
=1F. 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 150Cfor I
L
=1mA. For I
L =
100A and Tj=125C, 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,100AI
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.
LND2950 / LND2951
BLOCK DIAGRAM AND TYPICAL APPLICATIONS
APPLICATION HINTS
External Capacitors
A 1.0
F (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
F 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.
Linear Dimensions, Inc. 445 East Ohio Street, Chicago IL 60611 USA tel 312.321.1810 fax 312.321.1830
www.lineardimensions.com
Vout
See
Application
Hints
OUTPUT
I <= 100mA
L
GROUND
INPUT
+
-
ERROR
AMPLIFIER
+
+
1.23 V
Reference
Unregulated DC
+
Vout
See
Application
Hints
SENSE
I <= 100mA
L
GROUND
INPUT
+
-
ERROR
AMPLIFIER
+
FEEDBACK
+
-
60 mV
+
+
1.23 V
Reference
II
Error detection Comparator
OUTPUT
XX VTAP
ERROR
SHUTDOWN
From
CMOS
or
TTL
To
CMOS
or
TTL
Unregulated DC
330k
1
2
6
5
4
8
7
3
60k
+
TYPICAL APPLICATIONS
LND2950 / LND2951
Linear Dimensions, Inc. 445 East Ohio Street, Chicago IL 60611 USA tel 312.321.1810 fax 312.321.1830
www.lineardimensions.com
Wide Input Voltage Range Current Limiter
ERROR
OUTPUT
SHUTDOWN
INPUT
LND2951
GND
FB
8
1
7
4
3
5
ERROR
+V
IN
*V
IN
V
IN
OUT
*Minimum input-output voltage ranges from
40mV to 400mV, depending on load current.
Current limit is typically 160mA.
OUT
V
+V
1 F
LND29500Z-5.0
*V
OUT
5V
OUT
V
+V
IN
5V BUS
GND
*Minimum input-output voltage ranges from
40mV to 400mV, depending on load current.
Current limit is typically 160mA.
+
5V Current Limiter
LND2951
GND
FB
8
1
7
4
3
5
ERROR
+V
IN
IN
OUT
V
+V
SD
RESET
1 F
R1
R2
OUT
V
470k
470k
+
Latch Off When Error Flag Occurs
INPUT
1 F
1
4
1.2 30V
GND
SD
SHUTDOWN
8
1%
OUT
*V
V
= 1.23/R
I
1 F
IN
LND2951
+V=
3
7
I
L
R
FB
L
OUT
LOAD
V
+
Low Drift Current Source
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