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LM431
SNVS020H – MAY 2000 – REVISED JANUARY 2016
LM431 Adjustable Precision Zener Shunt Regulator
1 Features
•
•
1
3 Description
The LM431 is a 3-terminal adjustable shunt regulator
with ensured temperature stability over the entire
temperature range of operation. The output voltage
may be set at any level greater than 2.5 V (V
REF
) up
to 36 V merely by selecting two external resistors that
act as a voltage divided network. Due to the sharp
turnon characteristics this device is an excellent
replacement for many Zener diode applications.
The LM431 is available in space-saving SOIC-8,
SOT-23, and TO-92 packages.
Device Information
(1)
PART NUMBER
LM431
PACKAGE
SOIC (8)
SOT-23 (3)
TO-92 (3)
BODY SIZE (NOM)
4.90 mm × 3.91 mm
2.92 mm × 1.30 mm
4.30 mm × 4.30 mm
•
•
•
•
•
Average Temperature Coefficient 50 ppm/°C
Temperature Compensated for Operation Over
the Full Temperature Range
Programmable Output Voltage
Fast Turnon Response
Low-Output Noise
Low-Dynamic Output Impedance
Available in Space-Saving SOIC-8, SOT-23, and
TO-92 Packages
2 Applications
•
•
•
•
•
Adjustable Voltage or Current Linear and
Switching Power Supplies
Voltage Monitoring
Current Source and Sink Circuits
Circuits Requiring Precision References
Zener Diode Replacements
LM431 Symbol
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Functional Block Diagram
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
LM431
SNVS020H – MAY 2000 – REVISED JANUARY 2016
www.ti.com
Table of Contents
1
2
3
4
5
6
Features
..................................................................
Applications
...........................................................
Description
.............................................................
Revision History.....................................................
Pin Configuration and Functions
.........................
Specifications.........................................................
6.1
6.2
6.3
6.4
6.5
6.6
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
1
1
1
2
3
4
4
4
4
4
5
7
8.3 Feature Description.................................................
10
8.4 Device Functional Modes........................................
11
9
Application and Implementation
........................
12
9.1 Application Information............................................
12
9.2 Typical Applications ................................................
13
10 Power Supply Recommendations
.....................
19
11 Layout...................................................................
19
11.1 Layout Guidelines .................................................
19
11.2 Layout Example ....................................................
19
12 Device and Documentation Support
.................
20
12.1
12.2
12.3
12.4
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
20
20
20
20
7
8
Parameter Measurement Information
..................
7
Detailed Description
............................................
10
8.1 Overview .................................................................
10
8.2 Functional Block Diagram ......................................
10
13 Mechanical, Packaging, and Orderable
Information
...........................................................
20
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision G (March 2013) to Revision H
•
Page
Added
ESD Ratings
table,
Feature Description
section,
Device Functional Modes, Application and Implementation
section,
Power Supply Recommendations
section,
Layout
section,
Device and Documentation Support
section, and
Mechanical, Packaging, and Orderable Information
section ..................................................................................................
1
Changes from Revision F (April 2013) to Revision G
•
Page
Changed layout of National Data Sheet to TI format ...........................................................................................................
18
2
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LM431
Copyright © 2000–2016, Texas Instruments Incorporated
LM431
www.ti.com
SNVS020H – MAY 2000 – REVISED JANUARY 2016
5 Pin Configuration and Functions
D Package
8-Pin SOIC
Top View
DBZ Package
3-Pin SOT-23
Top View
Note: NC = Not internally connected.
LP Package
3-Pin TO-92
Top View
Pin Functions
PIN
NAME
Anode
Cathode
NC
Reference
SOIC
2, 3, 6, 7
1
4, 5
8
SOT-23
3
1
—
2
TO-92
3
1
—
2
I/O
O
I/O
—
I
DESCRIPTION
Anode pin, normally grounded
Shunt current/output voltage
No connect
Reference pin for adjustable output voltage
Copyright © 2000–2016, Texas Instruments Incorporated
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3
LM431
SNVS020H – MAY 2000 – REVISED JANUARY 2016
www.ti.com
6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)
(1) (2)
MIN
Cathode voltage
Reference voltage
Continuous cathode current
Reference input current
TO-92 package
Internal power
dissipation
(3) (4)
SOIC package
SOT-23 package
Operating temperature
Storage temperature
(1)
(2)
(3)
(4)
Industrial (LM431xI)
Commercial (LM431xC)
37
–0.5
–10
10
0.78
0.81
0.28
–40
0
–65
85
70
150
150
MAX
UNIT
V
V
mA
mA
W
W
W
°C
°C
°C
Stresses beyond those listed under
Absolute Maximum Ratings
may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under
Recommended
Operating Conditions.
Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
If Military/Aerospace specified devices are required, please contact the TI Sales Office/ Distributors for availability and specifications.
T
J Max
= 150°C.
Ratings apply to ambient temperature at 25°C. Above this temperature, derate the TO-92 at 6.2 mW/°C, the SOIC at 6.5 mW/°C, the
SOT-23 at 2.2 mW/°C.
6.2 ESD Ratings
VALUE
V
(ESD)
(1)
Electrostatic discharge
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001
(1)
±2500
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
Cathode voltage
Cathode current
V
REF
1
MAX
37
100
UNIT
V
mA
6.4 Thermal Information
LM431
THERMAL METRIC
(1)
R
θJA
R
θJC(top)
R
θJB
ψ
JT
ψ
JB
R
θJC(bot)
(1)
Junction-to-ambient thermal resistance
Junction-to-case (top) thermal resistance
Junction-to-board thermal resistance
Junction-to-top characterization parameter
Junction-to-board characterization parameter
Junction-to-case (bottom) thermal resistance
D (SOIC)
8 PINS
126.9
72.2
67.5
21.1
67
—
DBZ (SOT-23)
3 PINS
267.7
138.3
61
21.5
60.1
—
LP (TO-92)
3 PINS
162.4
85.8
—
29.4
141.5
—
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
UNIT
For more information about traditional and new thermal metrics, see the
Semiconductor and IC Package Thermal Metrics
application
report,
SPRA953.
4
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Copyright © 2000–2016, Texas Instruments Incorporated
LM431
www.ti.com
SNVS020H – MAY 2000 – REVISED JANUARY 2016
6.5 Electrical Characteristics
T
A
= 25°C unless otherwise specified
PARAMETER
TEST CONDITIONS
V
Z
= V
REF
, I
I
= 10 mA
LM431A (Figure
6
)
V
REF
Reference voltage
V
Z
= V
REF
, I
I
= 10 mA
LM431B (Figure
6
)
V
Z
= V
REF
, I
I
= 10 mA
LM431C (Figure
6
)
V
DEV
ΔV
REF
/
ΔV
Z
I
REF
∝I
REF
I
Z(MIN)
I
Z(OFF)
Deviation of reference input voltage
overtemperature
(1)
Ratio of the change in reference voltage to the
change in cathode voltage
Reference input current
Deviation of reference input current
overtemperature
Minimum cathode current for regulation
OFF-state current
V
Z
= V
REF
, I
I
= 10 mA,
T
A
= full range (Figure
6
)
I
Z
= 10 mA
(Figure
7
)
V
Z
from V
REF
to 10 V
V
Z
from 10 V to 36 V
MIN
2.44
2.47
2.485
TYP
2.495
2.495
2.5
8
−1.4
−1
2
0.4
0.4
0.3
MAX
2.55
2.52
2.51
17
−2.7
−2
4
1.2
1
1
mV
mV/V
μA
μA
mA
μA
V
UNIT
R
1
= 10 kΩ, R
2
=
∞,
I
I
= 10 mA
(Figure
7
)
R
1
= 10 kΩ, R
2
=
∞,
I
I
= 10 mA,
T
A
= full range (Figure
7
)
V
Z
= V
REF
(Figure
6
)
V
Z
= 36 V, V
REF
= 0 V (Figure
8)
(1)
Deviation of reference input voltage, V
DEV
, is defined as the maximum variation of the reference input voltage over the full temperature
range.
The average temperature coefficient of the reference input voltage,
∝V
REF
, is defined as:
Where:
T
2
– T
1
= full temperature change (0–70°C).
V
REF
can be positive or negative depending on whether the slope is positive or negative.
Example: V
DEV
= 8 mV, V
REF
= 2495 mV, T
2
– T
1
= 70°C, slope is positive.
Copyright © 2000–2016, Texas Instruments Incorporated
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