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LM431 Adjustable Precision Zener Shunt Regulator
March 2005
LM431
Adjustable Precision Zener Shunt Regulator
General Description
The LM431 is a 3-terminal adjustable shunt regulator with
guaranteed temperature stability over the entire temperature
range of operation. It is now available in a chip sized pack-
age (4-Bump micro SMD) using National’s micro SMD pack-
age technology. The output voltage may be set at any level
greater than 2.5V (V
REF
) up to 36V merely by selecting two
external resistors that act as a voltage divided network. Due
to the sharp turn-on characteristics this device is an excel-
lent replacement for many zener diode applications.
Features
n
Average temperature coefficient 50 ppm/˚C
n
Temperature compensated for operation over the full
temperature range
n
Programmable output voltage
n
Fast turn-on response
n
Low output noise
n
LM431 in micro SMD package
n
See AN-1112 for micro SMD considerations
Connection Diagrams
TO-92: Plastic Package
SOT-23: 3-Lead Small Outline
01005528
01005501
Top View
4-Bump micro SMD
Top View
SO-8: 8-Pin Surface Mount
01005554
01005502
Top view
Top View
(bump side down)
Note:
*NC = Not internally connected. Must be electrically isolated from the rest of the circuit for the microSMD package.
© 2005 National Semiconductor Corporation
DS010055
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LM431
Ordering Information
Package
Typical Accuracy Order Number/Package
Marking
0.5%
TO-92
LM431CCZ/
LM431CCZ
LM431CIZ/
LM431CIZ
SO-8
LM431CCM/
431CCM
LM431CCMX/
431CCM
LM431CIM/
431CIM
LM431CIMX/
431CIM
SOT-23
LM431CCM3/
N1B
1%
LM431BCZ/
LM431BCZ
LM431BIZ/
LM431BIZ
LM431BCM/
431BCM
2%
LM431ACZ/
LM431ACZ
LM431AIZ/
LM431AIZ
LM431ACM/
LM431ACM
0˚C to +70˚C
Rails
−40˚C to +85˚C
Rails
0˚C to +70˚C
Tape & Reel
M08A
Rails
−40˚C to +85˚C
Tape &Reel
Rails
0˚C to +70˚C
Tape & Reel
MF03A
Rails
−40˚C to +85˚C
Tape &Reel
250 Units Tape and
Reel
3k Units Tape and
Reel
Z03A
Temperature
Range
Transport Media
NSC
Drawing
LM431BCMX/ LM431ACMX/
431BCM
LM431ACM
LM431BIM/
431BIM
LM431BIMX/
431BIM
LM431AIM/
LM431AIM
LM431AIMX/
LM431AIM
LM431BCM3/ LM431ACM3/
N1D
N1F
LM431CCM3X/ LM431BCM3X/ LM431ACM3X/
N1B
N1D
N1F
LM431CIM3
N1A
LM431CIM3X
N1A
micro SMD
–
–
LM431BIM3
N1C
LM431AIM3
N1E
LM431BIM3X LM431AIM3X
N1C
N1E
LM431AIBP
LM431AIBPX
(Note 1)
−40˚C to +85˚C
BPA04AFB
Note 1:
The micro SMD package marking is a 1 digit manufacturing Date Code only
micro SMD Top View Marking Example
01005556
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2
LM431
Symbol and Functional Diagrams
01005599
01005555
DC Test Circuits
01005504
FIGURE 1. Test Circuit for V
Z
= V
REF
01005505
Note:
V
Z
= V
REF
(1 + R1/R2) + I
REF
•
R1
FIGURE 2. Test Circuit for V
Z
>
V
REF
01005506
Test Circuit for Off-State Current
3
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LM431
Absolute Maximum Ratings
(Note 2)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Storage Temperature Range
Operating Temperature Range
Industrial (LM431xI)
Commercial (LM431xC)
Soldering Information
Infrared or Convection (20 sec.)
Wave Soldering (10 sec.)
Cathode Voltage
Continuous Cathode Current
235˚C
260˚C (lead temp.)
37V
−10 mA to +150
mA
−40˚C to +85˚C
0˚C to +70˚C
−65˚C to +150˚C
Reference Voltage
Reference Input Current
Internal Power Dissipation (Notes 3,
4)
TO-92 Package
SO-8 Package
SOT-23 Package
micro SMD Package
Operating Conditions
Min
Cathode Voltage
Cathode Current
V
REF
1.0 mA
−0.5V
10 mA
0.78W
0.81W
0.28W
0.30W
Max
37V
100 mA
LM431
Electrical Characteristics
T
A
= 25˚C unless otherwise specified
Symbol
V
REF
Parameter
Reference Voltage
Conditions
V
Z
= V
REF
, I
I
= 10 mA
LM431A
(Figure 1
)
V
Z
= V
REF
, I
I
= 10 mA
LM431B
(Figure 1
)
V
Z
= V
REF
, I
I
= 10 mA
LM431C
(Figure 1
)
V
DEV
Deviation of Reference Input Voltage Over
Temperature (Note 5)
Ratio of the Change in Reference Voltage
to the Change in Cathode Voltage
I
REF
∝
I
REF
Reference Input Current
Deviation of Reference Input Current over
Temperature
I
Z(MIN)
I
Z(OFF)
r
Z
Minimum Cathode Current for Regulation
Off-State Current
Dynamic Output Impedance (Note 6)
V
Z
= V
REF
, I
I
= 10 mA,
T
A
= Full Range
(Figure 1
)
I
Z
= 10 mA
(Figure 2
)
V
Z
from V
REF
to 10V
V
Z
from 10V to 36V
−1.4
−1.0
2.0
−2.7
−2.0
4.0
µA
mV/V
8.0
17
mV
2.485
2.500
2.510
V
2.470
2.495
2.520
V
Min
2.440
Typ
2.495
Max
2.550
Units
V
R
1
= 10 kΩ, R
2
=
∞
,
I
I
= 10 mA
(Figure 2
)
R
1
= 10 kΩ, R
2
=
∞
,
I
I
= 10 mA,
T
A
= Full Range
(Figure 2
)
V
Z
= V
REF
(Figure 1
)
V
Z
= 36V, V
REF
= 0V
(Figure *NO
TARGET FOR fi*
)
V
Z
= V
REF
, LM431A,
Frequency = 0 Hz
(Figure 1
)
V
Z
= V
REF
, LM431B, LM431C
Frequency = 0 Hz
(Figure 1
)
0.4
0.4
0.3
1.2
1.0
1.0
0.75
0.50
µA
mA
µA
Ω
Ω
Note 2:
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Electrical specifications do not apply when operating the device
beyond its rated operating conditions.
Note 3:
T
J Max
= 150˚C.
Note 4:
Ratings apply to ambient temperature at 25˚C. Above this temperature, derate the TO-92 at 6.2 mW/˚C, the SO-8 at 6.5 mW/˚C, the SOT-23 at 2.2 mW/˚C
and the micro SMD at 3mW/˚C.
Note 5:
Deviation of reference input voltage, V
DEV
, is defined as the maximum variation of the reference input voltage over the full temperature range.
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