National Semiconductor LM4121 Technical data

April 2000

LM4121
Precision Micropower Low Dropout Voltage Reference

LM4121 Precision Micropower Low Dropout Voltage Reference

General Description

The LM4121 is a precision bandgap voltage reference avail­able 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 12Vconsuming 160 µA (Typ.) supply current.
In power down mode, device current drops to less than 2 µA.

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 −40˚C to +125˚C.

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 (−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 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:
n Supply current: 160 µA Typ.
n Low Temperature Coefficient: 50 ppm/˚C
n Enable pin
n Output voltages: 1.25V and Adjustable
n Industrial temperature Range: −40˚C to +85˚C
n (For extended temperature range, −40˚C to 125˚C,

contact National Semiconductor)

±

5mA

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

Block Diagram Connection Diagrams

DS101291-2

Refer to the Ordering Information Table in this Data Sheet for Specific
Part Number

SOT23-5 Surface Mount Package

DS101291-1

*

Resistors are removed on the LM4121-ADJ

†

LM4121-ADJ only

LM4121-1.2 Block Diagram

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© 2001 National Semiconductor Corporation DS101291 www.national.com

Ordering Information

LM4121

Industrial Temperature Range (−40˚C to + 85˚C)

Initial Output Voltage Accuracy at 25˚C

And Temperature Coefficient

0.2%, 50 ppm/˚C max (A grade)

0.5%, 50 ppm/˚C max

LM4121 Supplied as

1000 Units, Tape and

Reel

LM4121AIM5-1.2 LM4121AIM5X-1.2 R19A

LM4121AIM5-ADJ LM4121AIM5X-ADJ R20A

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 Supplied as

3000 Units, Tape and

Reel

Top

Marking

www.national.com 2

LM4121

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

Lead Temperature:

Soldering, (10 sec.) +260˚C
Vapor Phase (60 sec.) +215˚C

Infrared (15 sec.) +220˚C
Maximum Voltage on input or
enable pins −0.3V to 14V

Output Short-Circuit Duration Indefinite
Power Dissipation (T

MA05B package − θ

= 25˚C) (Note 2):

A

JA

280˚C/W

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

Power Dissipation 350 mW

ESD Susceptibility (Note 3)

Human Body Model
Machine Model

2kV

200V

Electrical Characteristics
LM4121-1.250V

standard typeface are for T

Symbol Parameter Conditions Min (Note 5) Typ (Note 4) Max (Note 5) Units

V

OUT

TCV

∆V

∆V

Min-V
V

I

I

V
V

I
I

I

/˚C Temperature Coefficient −40˚C ≤ TA≤ +125˚C 14 50 ppm/˚c

OUT

/∆V

OUT

/∆I

OUT

IN

N

S

SS

H
L

H
L

SC

Hyst Thermal Hysteresis

∆V

OUT

Output Voltage Initial
Accuracy
LM4121A-1.250

LM4121-1.250

Line Regulation 1.8V ≤ VIN≤ 12V 0.0007 0.009

IN

Load Regulation

LOAD

Minimum Operating Voltage I
Output Noise Voltage 0.1 Hz to 10 Hz 20 µV

Supply Current 160 250

Power-down Supply Current VIN= 12V

Logic High Input Voltage 1.6 1.5 V
Logic Low Input Voltage 0.4 V

Logic High Input Current 7 15 µA
Logic Low Input Current 0.1 µA

Short Circuit Current

(Note 8)
Long Term Stability

(Note 9)

Unless otherwise specified VIN= 3.3V, I

= 25˚C, and limits in boldface type apply over the −40˚C ≤ TA≤ +85˚C temperature range.

j

LOAD

=0,C

= 0.01µF, TA=Tj= 25˚C. Limits with

OUT

1.250

±

0.2

±

0.5

0.012

0mA≤I

≤ 1 mA 0.03 0.08

LOAD

0.17

1mA≤I

≤ 5 mA 0.01 0.04

LOAD

0.1

−1 mA ≤ I

−5 mA ≤ I
= 5mA 1.5 1.8 V

LOAD

≤ 0 mA 0.04 0.12

LOAD

≤ −1 mA 0.01

LOAD

10 Hz to 10 kHz 30 µV

275

Enable = 0.4V

Enable = 0.2V

1

2

0.2

V

IN

= 3.3V, V

=0 15

OUT

630

V

= 12V, V

IN

=0 17

OUT

630

−40˚C ≤ T

≤ 125˚C 0.5 mV/V

A

1000 hrs.@25˚C 100 ppm

%

%/V

%/mA

PP

RMS

µA

µA

mA

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Electrical Characteristics
LM4121-ADJ

LM4121

its with standard typeface are for T
range.

Symbol Parameter Conditions Min (Note 5) Typ (Note 4) Max (Note 5) Units

V

OUT=VREF

TCV

/˚C Temperature Coefficient −40˚C ≤ TA≤ +125˚C 14 50 ppm/˚c

REF

∆V

/∆V

REF

IN

∆V

/∆I

OUT

LOAD

Min-V

IN

V

N

I

S

I

SS

I

BIAS

V

H

V

L

I

H

I

L

I

SC

Hyst Thermal Hysteresis

∆V

OUT

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 T
junction temperature), θ
=(T

JMAX−TA

Note 3: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor 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: Output noise for 1.25V option. Noise is proportional to V
Note 7: Bias Current flows out of the Adjust pin.
Note 8: Thermal hysteresis is defined as the change in +25˚C output voltage before and after exposing the device to temperature extremes.
Note 9: Long term stability is change in V

)/θ

J-A

Unless otherwise specified VIN= 3.3V, V

= 25˚C, and limits in boldface type apply over the −40˚C ≤ TA≤ +85˚C temperature

j

OUT=VREF,ILOAD

=0,C

= 0.01µF, TA=Tj= 25˚C. Lim-

OUT

Output Voltage Initial

±

Accuracy

1.216

0.2

LM4121A-ADJ
LM4121-ADJ

±

0.5

Line Regulation 1.8V ≤ VIN≤ 12V 0.0007 0.009

0.012

0mA≤I

≤ 1 mA 0.03 0.08

LOAD

0.17

Load Regulation

Minimum Operating Voltage I

1mA≤I

−1 mA ≤ I

−5 mA ≤ I
=5mA 1.5 1.8 V

LOAD

≤ 5 mA 0.01 0.04

LOAD

≤ 0 mA 0.04 0.12

LOAD

≤ −1 mA 0.01

LOAD

0.1

Output Noise Voltage (Note 6) 0.1 Hz to 10 Hz 20 µV

10 Hz to 10 kHz 30 µV

Supply Current 160 250

275

Power-down Supply Current VIN= 12V

Enable = 0.4V

Enable = 0.2V

1

2

Reference Pin Bias Current (Note 7) 15 40 nA
Logic High Input Voltage 1.6 1.5 V
Logic Low Input Voltage 0.4 V

0.2

Logic High Input Current 7 15 µA
Logic Low Input Current 0.1 µA

=0 15

V

OUT

Short Circuit Current

V

= 12V, V

IN

=0 17

OUT

630

630

−40˚C ≤ T

≤ 125˚C 0.5 mV/V

A

(Note 8)
Long Term Stability

1000 hrs.@25˚C 100 ppm

(Note 9)

(junction to ambient thermal resistance) and TA(ambient temperature). The maximum power dissipation at any temperature is: PDiss

J-A

up to the value listed in the Absolute Maximum Ratings.

.

OUT

at 25˚C measured continuously during 1000 hrs.

REF

JMAX

%

%/V

%/mA

PP

RMS

µA

µA

mA

(maximum

MAX

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LM4121

LM4121- (All Options) Typical Operating Characteristics Unless otherwise specified, V

= 3.3V, V

Minimum Input Voltage vs Temperature

GND Pin Current at No Load
vs Temperature

OUT

= 1.25V, I

LOAD

=0,C

= 0.022µF, TA= 25˚C and VEN=VIN.

OUT

GND Pin Current vs V

DS101291-12

GND Pin Current vs Load

IN

DS101291-13

IN

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