LM4120
LM4120 Precision Micropower Low Dropout Voltage Reference
Literature Number: SNVS049B
LM4120
Precision Micropower Low Dropout Voltage Reference
General Description
The LM4120 is a precision low power low dropout bandgap
voltage reference with up to 5 mA output current source and
sink capability.
This series reference operates with input voltages as low as
2V and up to 12V consuming 160 µA (Typ.) supply current. In
power down mode, device current drops to less than 2 µA.
The LM4120 comes in two grades (A and Standard) and
seven voltage options for greater flexibility. The best grade
devices (A) have an initial accuracy of 0.2%, while the stan-
dard have an initial accuracy of 0.5%, both with a tempco of
50ppm/˚C guaranteed from −40˚C to +125˚C.
The very low dropout voltage, low supply current and power-
down capability of the LM4120 makes this product an ideal
choice for battery powered and portable applications.
The device performance is guaranteed over the industrial
temperature range (−40˚C to +85˚C), while certain specs are
guaranteed over the extended temperature range (−40˚C to
+125˚C). Please contact National for full specifications over
the extended temperature range. The LM4120 is available in
a standard 5-pin SOT-23 package.
Features
nSmall SOT23-5 package
nLow dropout voltage: 120 mV Typ @1mA
nHigh output voltage accuracy: 0.2%
nSource and Sink current output: ±5mA
nSupply current: 160 µA Typ.
nLow Temperature Coefficient: 50 ppm/˚C
nEnable pin
nFixed output voltages: 1.8, 2.048, 2.5, 3.0, 3.3, 4.096
and 5.0V
nIndustrial temperature Range: −40˚C to +85˚C
n(For extended temperature range, −40˚C to 125˚C,
contact National Semiconductor)
Applications
nPortable, battery powered equipment
nInstrumentation and process control
nAutomotive & Industrial
nTest equipment
nData acquisition systems
nPrecision regulators
nBattery chargers
nBase stations
nCommunications
nMedical equipment
Functional Block Diagram
10104701
Connection Diagram
10104702
Refer to the Ordering Information Table in this Data Sheet for Specific
Part Number
SOT23-5 Surface Mount Package
March 2005
LM4120 Precision Micropower Low Dropout Voltage Reference
© 2005 National Semiconductor Corporation DS101047 www.national.com
Ordering Information
Industrial Temperature Range (−40˚C to + 85˚C)
Initial Output Voltage Accuracy at 25˚C
And Temperature Coefficient
LM4120 Supplied as
1000 Units, Tape and
Reel
LM4120 Supplied as
3000 Units, Tape and
Reel
Top
Marking
0.2%, 50 ppm/˚C max (A grade)
LM4120AIM5-1.8 LM4120AIM5X-1.8 R21A
LM4120AIM5-2.0 LM4120AIM5X-2.0 R14A
LM4120AIM5-2.5 LM4120AIM5X-2.5 R08A
LM4120AIM5-3.0 LM4120AIM5X-3.0 R15A
LM4120AIM5-3.3 LM4120AIM5X-3.3 R16A
LM4120AIM5-4.1 LM4120AIM5X-4.1 R17A
LM4120AIM5-5.0 LM4120AIM5X-5.0 R18A
0.5%, 50 ppm/˚C max
LM4120IM5-1.8 LM4120IM5X-1.8 R21B
LM4120IM5-2.0 LM4120IM5X-2.0 R14B
LM4120IM5-2.5 LM4120IM5X-2.5 R08B
LM4120IM5-3.0 LM4120IM5X-3.0 R15B
LM4120IM5-3.3 LM4120IM5X-3.3 R16B
LM4120IM5-4.1 LM4120IM5X-4.1 R17B
LM4120IM5-5.0 LM4120IM5X-5.0 R18B
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:
21 = 1.800V Voltage Option
14 = 2.048V Voltage Option
08 = 2.500V Voltage Option
15 = 3.000V Voltage Option
16 = 3.300V Voltage Option
17 = 4.096V Voltage Option
18 = 5.000V Voltage Option
Fourth Field:
A-B = Initial Reference Voltage Tolerance
A=±0.2%
B=±0.5%
LM4120
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.
Maximum Voltage on input or
enable pins −0.3V to 14V
Output Short-Circuit Duration Indefinite
Power Dissipation (T
A
= 25˚C) (Note 2):
MA05B package − θ
JA
280˚C/W
Power Dissipation 350 mW
ESD Susceptibility (Note 3)
Human Body Model
Machine Model
2kV
200V
Lead Temperature:
Soldering, (10 sec.) +260˚C
Vapor Phase (60 sec.) +215˚C
Infrared (15 sec.) +220˚C
Operating Range (Note 1)
Storage Temperature
Range −65˚C to +150˚C
Ambient Temperature
Range −40˚C to +85˚C
Junction Temperature
Range −40˚C to +125˚C
Electrical Characteristics
LM4120-1.8V, 2.048V and 2.5V Unless otherwise specified V
IN
= 3.3V, I
LOAD
=0,C
OUT
= 0.01µF, T
A
=
T
j
= 25˚C. Limits with standard typeface are for T
j
= 25˚C, and limits in boldface type apply over the −40˚C ≤T
A
≤+85˚C
temperature range.
Symbol Parameter Conditions Min (Note 5) Typ (Note
4)
Max (Note
5) Units
V
OUT
Output Voltage Initial
Accuracy
LM4120A-1.800
LM4120A-2.048
LM4120A-2.500
±0.2 %
LM4120-1.800
LM4120-2.048
LM4120-2.500
±0.5 %
TCV
OUT
/˚C Temperature
Coefficient
−40˚C ≤T
A
≤+125˚C 14 50 ppm/˚c
∆V
OUT
/∆V
IN
Line Regulation 3.3V ≤V
IN
≤12V 0.0007 0.008
0.01 %/V
∆V
OUT
/∆I
LOAD
Load Regulation
0mA≤I
LOAD
≤1 mA 0.03 0.08
0.17
%/mA
1mA≤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
V
IN
−V
OUT
Dropout Voltage
(Note 6)
I
LOAD
=0mA 45 65
80
mV
I
LOAD
= +1 mA 120 150
180
I
LOAD
= +5 mA 180 210
250
V
N
Output Noise Voltage
(Note 8)
0.1 Hz to 10 Hz 20 µV
PP
10 Hz to 10 kHz 36 µV
PP
I
S
Supply Current 160 250
275
µA
I
SS
Power-down Supply
Current
Enable = 0.4V
−40˚C ≤T
J
≤+85˚C
Enable = 0.2V
1
2µA
V
H
Logic High Input
Voltage
2.4 V
2.4
LM4120
www.national.com3
Electrical Characteristics
LM4120-1.8V, 2.048V and 2.5V Unless otherwise specified V
IN
= 3.3V, I
LOAD
=0,C
OUT
= 0.01µF, T
A
=T
j
= 25˚C. Limits with standard typeface are for T
j
= 25˚C, and limits in boldface type apply over the −40˚C ≤T
A
≤+85˚C
temperature range. (Continued)
Symbol Parameter Conditions Min (Note 5) Typ (Note
4)
Max (Note
5) Units
V
L
Logic Low Input
Voltage
0.4 V
0.2
I
H
Logic High Input
Current
715 µA
I
L
Logic Low Input
Current
0.1 µA
I
SC
Short Circuit Current
V
IN
= 3.3V, V
OUT
=0 15
mA
630
V
IN
= 12V, V
OUT
=0 17
630
Hyst Thermal Hysteresis
(Note 7)
−40˚C ≤T
A
≤125˚C 0.5 mV/V
∆V
OUT
Long Term Stability
(Note 9)
1000 hrs. @25˚C 100 ppm
Electrical Characteristics
LM4120-3.0V, 3.3V, 4.096V and 5.0V Unless otherwise specified V
IN
=V
OUT
+ 1V, I
LOAD
=0,C
OUT
=
0.01µF, T
A
=T
j
= 25˚C. Limits with standard typeface are for T
j
= 25˚C, and limits in boldface type apply over the −40˚C ≤
T
A
≤+85˚C temperature range.
Symbol Parameter Conditions Min (Note 5) Typ (Note
4)
Max (Note
5) Units
V
OUT
Output Voltage Initial
Accuracy
LM4120A-3.000
LM4120A-3.300
LM4120A-4.096
LM4120A-5.000
±0.2 %
LM4120-3.000
LM4120-3.300
LM4120-4.096
LM4120-5.000
±0.5 %
TCV
OUT
/˚C Temperature
Coefficient
−40˚C ≤T
A
≤+125˚C 14 50 ppm/˚c
∆V
OUT
/∆V
IN
Line Regulation (V
OUT
+ 1V) ≤V
IN
≤12V 0.0007 0.008
0.01 %/V
∆V
OUT
/∆I
LOAD
Load Regulation
0mA≤I
LOAD
≤1 mA 0.03 0.08
0.17
%/mA
1mA≤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
V
IN
−V
OUT
Dropout Voltage
(Note 6)
I
LOAD
=0mA 45 65
80
mV
I
LOAD
= +1 mA 120 150
180
I
LOAD
= +5 mA 180 210
250
LM4120
www.national.com 4
Electrical Characteristics
LM4120-3.0V, 3.3V, 4.096V and 5.0V Unless otherwise specified V
IN
=V
OUT
+ 1V, I
LOAD
=0,C
OUT
=
0.01µF, T
A
=T
j
= 25˚C. Limits with standard typeface are for T
j
= 25˚C, and limits in boldface type apply over the −40˚C ≤T
A
≤+85˚C temperature range. (Continued)
Symbol Parameter Conditions Min (Note 5) Typ (Note
4)
Max (Note
5) Units
V
N
Output Noise Voltage
(Note 8)
0.1 Hz to 10 Hz 20 µV
PP
10 Hz to 10 kHz 36 µV
PP
I
S
Supply Current 160 250
275
µA
I
SS
Power-down Supply
Current
Enable = 0.4V
−40˚C ≤T
J
≤+85˚C
Enable = 0.2V
1
2µA
V
H
Logic High Input
Voltage
2.4 V
2.4
V
L
Logic Low Input
Voltage
0.4 V
0.2
I
H
Logic High Input
Current
715 µA
I
L
Logic Low Input
Current
0.1 µA
I
SC
Short Circuit Current
V
OUT
=0 15
mA
630
V
IN
= 12V, V
OUT
=0 17
630
Hyst Thermal Hysteresis
(Note 7)
−40˚C ≤T
A
≤125˚C 0.5 mV/V
∆V
OUT
Long Term Stability
(Note 9)
1000 hrs. @25˚C 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
guaranteed 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 TJMAX (maximum
junction temperature), θJ-A (junction to ambient thermal resistance) and TA(ambient temperature). The maximum power dissipation at any temperature is: PDissMAX
=(T
JMAX −T
A)/θJ-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 kΩresistor into each pin. The machine model is a 200 pF capacitor discharged
directly into each pin.
Note 4: Typical numbers are at 25˚C and represent the most likely parametric norm.
Note 5: Limits are 100% production tested at 25˚C. 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: Dropout voltage is the differential voltage between VOUT and VIN at which VOUT changes ≤1% from VOUT at VIN = 3.3V for 1.8V, 2.0V, 2.5V and VOUT +
1V for others.For 1.8V option, dropout voltage is not guaranteed over temperature. A parasitic diode exists between input and output pins; it will conduct if VOUT is
pulled to a higher voltage than VIN.
Note 7: Thermal hysteresis is defined as the change in +25˚C output voltage before and after exposing the device to temperature extremes.
Note 8: Output noise voltage is proportional to VOUT.V
Nfor other voltage option is calculated using (VN(1.8V)/1.8) * VOUT.V
N(2.5V) = (36µVPP/1.8) * 2.5 = 46µVPP.
Note 9: Long term stability is change in VREF at 25˚C measured continuously during 1000 hrs.
LM4120
www.national.com5
LM4120 Typical Operating Characteristics
Unless otherwise specified, V
IN
= 3.3V, V
OUT
= 2.5V,
I
LOAD
=0,C
OUT
= 0.022µF, T
A
= 25˚C and V
EN
=V
IN
.
Long Term Drift Typical Temperature Drift
10104712 10104713
Short Circuit Current vs Temperature Dropout Voltage vs Output Error
10104714
10104715
Dropout Voltage vs Load Current Line Regulation
10104733 10104717
LM4120
www.national.com 6
LM4120 Typical Operating Characteristics Unless otherwise specified, V
IN
= 3.3V, V
OUT
= 2.5V,
ILOAD =0,C
OUT
= 0.022µF, T
A
= 25˚C and V
EN
=V
IN
. (Continued)
Load Regulation GND Pin Current
10104718 10104719
GND Pin Current at No Load
vs Temperature GND Pin Current vs Load
10104721 10104722
0.1Hz to 10Hz output Noise Output Impedance vs Frequency
10104723
10104724
LM4120
www.national.com7
LM4120 Typical Operating Characteristics Unless otherwise specified, V
IN
= 3.3V, V
OUT
= 2.5V,
ILOAD =0,C
OUT
= 0.022µF, T
A
= 25˚C and V
EN
=V
IN
. (Continued)
PSRR vs Frequency Start-Up Response
10104725 10104726
Enable Response Load Step Response
10104727 10104728
Load Step Response Line Step Response
10104729 10104730
LM4120
www.national.com 8
LM4120 Typical Operating Characteristics Unless otherwise specified, V
IN
= 3.3V, V
OUT
= 2.5V,
ILOAD =0,C
OUT
= 0.022µF, T
A
= 25˚C and V
EN
=V
IN
. (Continued)
Thermal Hysteresis Enable Pin Current
10104731 10104716
Pin Functions
Output (Pin 5): Reference Output.
Input (Pin 4):Positive Supply.
Ground (Pin 2):Negative Supply or Ground Connection.
Enable (Pin 3):Pulled to input for normal operation. Forcing
this pin to ground will turn-off the output.
REF (Pin 1):REF Pin. This pin should be left unconnected.
Application Hints
The standard application circuit for the LM4120 is shown in
Figure 1. It is designed to be stable with ceramic output
capacitors in the range of 0.022µF to 0.047µF. Note that
0.022µF is the minimum required output capacitor. These
capacitors typically have an ESR of about 0.1 to 0.5Ω.
Smaller ESR can be tolerated, however larger ESR can not.
The output capacitor can be increased to improve load tran-
sient response, up to about 1µF. However, values above
0.047µF must be tantalum. With tantalum capacitors, in the
1µF range, a small capacitor between the output and the
reference pin is required. This capacitor will typically be in
the 50pF range. Care must be taken when using output
capacitors of 1µF or larger. These application must be thor-
oughly tested over temperature, line and load.
An input capacitor is typically not required. However, a 0.1µF
ceramic can be used to help prevent line transients from
entering the LM4120. Larger input capacitors should be
tantalum or aluminium.
The reference pin is sensitive to noise, and capacitive load-
ing. Therefore, the PCB layout should isolate this pin as
much as possible.
The enable pin is an analog input with very little hysteresis.
About 6µA into this pin is required to turn the part on, and it
must be taken close to GND to turn the part off (see spec.
table for thresholds). There is a minimum slew rate on this
pin of about 0.003V/µS to prevent glitches on the output. All
of these conditions can easily be met with ordinary CMOS or
TTL logic. If the shutdown feature is not required, then this
pin can safely be connected directly to the input supply.
Floating this pin is not recommended.
INPUT CAPACITOR
Noise on the power-supply input can effect the output noise,
but can be reduced by using an optional bypass capacitor
between the input pin and the ground.
PRINTED CIRCUIT BOARD LAYOUT CONSIDERATION
The mechanical stress due to PC board mounting can cause
the output voltage to shift from its initial value. References in
SOT packages are generally less prone to assembly stress
than devices in Small Outline (SOIC) package.
To reduce the stress-related output voltage shifts, mount the
reference on the low flex areas of the PC board such as near
to the edge or the corner of the PC board.
10104732
FIGURE 1.
LM4120
www.national.com9
Typical Application Circuits
Voltage Reference with Negative Output
10104703
Precision High Current Low Dropout Regulator
10104704
Precision High Current
Negative Voltage Regulator
10104705
Voltage Reference with Complimentary Output
10104706
Precision High Current Low Droput Regulator
10104707
Stacking Voltage References
10104708
Precision Voltage Reference
with Force and Sense Output
10104709
LM4120
www.national.com 10
Typical Application Circuits
(Continued)
Programmable Current Source
10104710
Precision Regulator with Current Limiting Circuit
10104711
Power Supply Splitter
10104720
LM4120
www.national.com11
Physical Dimensions inches (millimeters) unless otherwise noted
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves
the right at any time without notice to change said circuitry and specifications.
For the most current product information visit us at www.national.com.
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS
WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR
CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body, or
(b) support or sustain life, and whose failure to perform when
properly used in accordance with instructions for use
provided in the labeling, can be reasonably expected to result
in a significant injury to the user.
2. A critical component is any component of a life support
device or system whose failure to perform can be reasonably
expected to cause the failure of the life support device or
system, or to affect its safety or effectiveness.
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National Semiconductor manufactures products and uses packing materials that meet the provisions of the Customer Products
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no ‘‘Banned Substances’’ as defined in CSP-9-111S2.
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Support Center
Email: new.feedback@nsc.com
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www.national.com
LM4120 Precision Micropower Low Dropout Voltage Reference
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