LM4121
Precision Micropower Low Dropout Voltage Reference
General Description
The LM4121 is a precision bandgap voltage reference avail-
able in a fixed 1.25V and adjustable version with up to 5 mA
current source and sink capability.
This series reference operates with input voltages as low as
1.8V and up to 12V consuming 160 A (Typ.) supply current.
In power down mode, device current drops to less than 2 A.
The LM4121 comes in two grades A and Standard. The best
grade devices (A) have an initial accuracy of 0.2%, while the
standard have an initial accuracy of 0.5%, both with a
tempco of 50ppm/C guaranteed from -40C to +125C.
The very low operating voltage, low supply current and
power-down capability of the LM4121 makes this product an
ideal choice for battery powered and portable applications.
The device performance is guaranteed over the industrial
temperature range (-40C to +85C), while certain specs are
guaranteed over the extended temperature range (-40C to
+125C). Please contact National for full specifications over
the extended temperature range. The LM4121 is available in
a standard 5-pin SOT-23 package.
Features (LM4121-1.2)
n
Small SOT23-5 package
n
Low voltage operation
n
High output voltage accuracy:
0.2%
n
Source and Sink current output:
5 mA
n
Supply current:
160 A Typ.
n
Low Temperature Coefficient:
50 ppm/C
n
Enable pin
n
Output voltages:
1.25V and Adjustable
n
Industrial temperature Range:
-40C to +85C
n
(For extended temperature range, -40C to 125C,
contact National Semiconductor)
Applications
n
Portable, battery powered equipment
n
Instrumentation and process control
n
Automotive & Industrial
n
Test equipment
n
Data acquisition systems
n
Precision regulators
n
Battery chargers
n
Base stations
n
Communications
n
Medical equipment
Connection Diagram
LM4121-1.2 Block Diagram
DS101291-1
*
Resistors are removed on the LM4121-ADJ
LM4121-ADJ only
DS101291-2
Refer to the Ordering Information Table in this Data Sheet for Specific
Part Number
SOT23-5 Surface Mount Package
DS101291-35
April 2000
LM4121
Precision
Micropower
Low
Dropout
V
oltage
Reference
2000 National Semiconductor Corporation
DS101291
www.national.com
Ordering Information
Industrial Temperature Range (-40C to + 85C)
Initial Output Voltage Accuracy at 25C
And Temperature Coefficient
LM4121 Supplied as
1000 Units, Tape and
Reel
LM4121 Supplied as
3000 Units, Tape and
Reel
Top
Marking
0.2%, 50 ppm/C max (A grade)
LM4121AIM5-1.2
LM4121AIM5X-1.2
R19A
LM4121AIM5-ADJ
LM4121AIM5X-ADJ
R20A
0.5%, 50 ppm/C max
LM4121IM5-1.2
LM4121IM5X-1.2
R19B
LM4121IM5-ADJ
LM4121IM5X-ADJ
R20B
SOT-23 Package Marking Information
Only four fields of marking are possible on the SOT-23's small surface. This
table gives the meaning of the four fields.
Field Information
First Field:
R = Reference
Second and third Field:
19 = 1.250V Voltage Option
20 = Adjustable
Fourth Field:
A-B = Initial Reference Voltage Tolerance
A =
0.2%
B =
0.5%
LM4121
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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.
Maximum Voltage on input or
enable pins
-0.3V to 14V
Output Short-Circuit Duration
Indefinite
Power Dissipation (T
A
= 25C) (Note 2):
MA05B package -
JA
280C/W
Power Dissipation
350 mW
ESD Susceptibility (Note 3)
Human Body Model
Machine Model
2 kV
200V
Lead Temperature:
Soldering, (10 sec.)
+260C
Vapor Phase (60 sec.)
+215C
Infrared (15 sec.)
+220C
Operating Range
(Note 1)
Storage Temperature Range
-65C to +150C
Ambient Temperature Range
-40C to +85C
Junction Temperature Range
-40C to +125C
Electrical Characteristics
LM4121-1.250V
Unless otherwise specified V
IN
= 3.3V, I
LOAD
= 0, C
OUT
= 0.01F, T
A
= T
j
= 25C. Limits with
standard typeface are for T
j
= 25C, and limits in boldface type apply over the -40C
T
A
+85C temperature range.
Symbol
Parameter
Conditions
Min (Note 5)
Typ (Note 4)
Max (Note 5)
Units
V
OUT
Output Voltage Initial
Accuracy
LM4121A-1.250
1.250
0.2
%
LM4121-1.250
0.5
TCV
OUT
/C
Temperature Coefficient
-40C
T
A
+125C
14
50
ppm/c
V
OUT
/
V
IN
Line Regulation
1.8V
V
IN
12V
0.0007
0.009
0.012
%/V
V
OUT
/
I
LOAD
Load Regulation
0 mA
I
LOAD
1 mA
0.03
0.08
0.17
%/mA
1 mA
I
LOAD
5 mA
0.01
0.04
0.1
-1 mA
I
LOAD
0 mA
0.04
0.12
-5 mA
I
LOAD
-1 mA
0.01
Min-V
IN
Minimum Operating Voltage
I
LOAD
= 5mA
1.5
1.8
V
V
N
Output Noise Voltage
0.1 Hz to 10 Hz
20
V
PP
10 Hz to 10 kHz
30
V
RMS
I
S
Supply Current
160
250
275
A
I
SS
Power-down Supply Current
V
IN
= 12V
Enable = 0.4V
Enable = 0.2V
1
2
A
V
H
Logic High Input Voltage
1.6
1.5
V
V
L
Logic Low Input Voltage
0.4
V
0.2
I
H
Logic High Input Current
7
15
A
I
L
Logic Low Input Current
0.1
A
I
SC
Short Circuit Current
V
IN
= 3.3V, V
OUT
= 0
15
mA
6
30
V
IN
= 12V, V
OUT
= 0
17
6
30
Hyst
Thermal Hysteresis
(Note 8)
-40C
T
A
125C
0.5
mV/V
V
OUT
Long Term Stability
(Note 9)
1000 hrs.
@
25C
100
ppm
LM4121
www.national.com
3
Electrical Characteristics
LM4121-ADJ
Unless otherwise specified V
IN
= 3.3V, V
OUT
= V
REF
, I
LOAD
= 0, C
OUT
= 0.01F, T
A
= T
j
= 25C. Lim-
its with standard typeface are for T
j
= 25C, and limits in boldface type apply over the -40C
T
A
+85C temperature
range.
Symbol
Parameter
Conditions
Min (Note 5)
Typ (Note 4)
Max (Note 5)
Units
V
OUT
= V
REF
Output Voltage Initial
Accuracy
LM4121A-ADJ
1.216
0.2
%
LM4121-ADJ
0.5
TCV
REF
/C
Temperature Coefficient
-40C
T
A
+125C
14
50
ppm/c
V
REF
/
V
IN
Line Regulation
1.8V
V
IN
12V
0.0007
0.009
0.012
%/V
V
OUT
/
I
LOAD
Load Regulation
0 mA
I
LOAD
1 mA
0.03
0.08
0.17
%/mA
1 mA
I
LOAD
5 mA
0.01
0.04
0.1
-1 mA
I
LOAD
0 mA
0.04
0.12
-5 mA
I
LOAD
-1 mA
0.01
Min-V
IN
Minimum Operating Voltage
I
LOAD
= 5 mA
1.5
1.8
V
V
N
Output Noise Voltage (Note 6)
0.1 Hz to 10 Hz
20
V
PP
10 Hz to 10 kHz
30
V
RMS
I
S
Supply Current
160
250
275
A
I
SS
Power-down Supply Current
V
IN
= 12V
Enable = 0.4V
Enable = 0.2V
1
2
A
I
BIAS
Reference Pin Bias Current
(Note 7)
15
40
nA
V
H
Logic High Input Voltage
1.6
1.5
V
V
L
Logic Low Input Voltage
0.4
V
0.2
I
H
Logic High Input Current
7
15
A
I
L
Logic Low Input Current
0.1
A
I
SC
Short Circuit Current
V
OUT
= 0
15
mA
6
30
V
IN
= 12V, V
OUT
= 0
17
6
30
Hyst
Thermal Hysteresis
(Note 8)
-40C
T
A
125C
0.5
mV/V
V
OUT
Long Term Stability
(Note 9)
1000 hrs.
@
25C
100
ppm
Note 1: "Absolute Maximum Ratings" indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see Electrical Characteristics. The guar-
anteed specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test
conditions.
Note 2: Without PCB copper enhancements. The maximum power dissipation must be de-rated at elevated temperatures and is limited by T
JMAX
(maximum junction
temperature),
J-A
(junction to ambient thermal resistance) and T
A
(ambient temperature). The maximum power dissipation at any temperature is: PDiss
MAX
= (T
JMAX
- T
A
)/
J-A
up to the value listed in the Absolute Maximum Ratings.
Note 3: The human body model is a 100 pF capacitor discharged through a 1.5 k
resistor into each pin. The machine model is a 200 pF capacitor discharged di-
rectly into each pin.
Note 4: Typical numbers are at 25C and represent the most likely parametric norm.
Note 5: Limits are 100% production tested at 25C. Limits over the operating temperature range are guaranteed through correlation using Statistical Quality Control
(SQC) methods. The limits are used to calculate National's Averaging Outgoing Quality Level (AOQL).
Note 6: Output noise for 1.25V option. Noise is proportional to V
OUT
.
Note 7: Bias Current flows out of the Adjust pin.
Note 8: Thermal hysteresis is defined as the change in +25C output voltage before and after exposing the device to temperature extremes.
Note 9: Long term stability is change in V
REF
at 25C measured continuously during 1000 hrs.
LM4121
www.national.com
4
LM4121- (All Options) Typical Operating Characteristics
Unless otherwise specified, V
IN
= 3.3V, V
OUT
= 1.25V, I
LOAD
= 0, C
OUT
= 0.022F, T
A
= 25C and V
EN
= V
IN
.
Minimum Input Voltage vs Temperature
DS101291-12
GND Pin Current vs V
IN
DS101291-13
GND Pin Current at No Load
vs Temperature
DS101291-14
GND Pin Current vs Load
DS101291-15
LM4121
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5
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