Shunt Regulator
LM431 LM431A LM431B
Shunt Regulator
General Description
•
The LM431 Series ICs are three-terminal programmable
shunt regulators with guaranteed thermal stability over a
full operation range. These monolithic ICs voltage reference
operate as a low temperature coefficient Zener which is
programmable from Vref to 36V with two external resistors.
These devices exhibit a wide operating current range of 1.0 to
100mA with a typical dynamic impedance of 0.15 to 0.22Ω. The
characteristics of these references make them excellent
replacements for Zener diodes in many applications such as
digital voltmeters, power supplies and op amp circuitry
The 2.5V reference makes it convenient to obtain a stable
reference from 5.0V logic supplies, and since the LM431 series
operates as a shunt regulator, it can be used as either a positive or
negative voltage reference.
TO-92
SOT-23
SOT-23-5
SOP-8
SOT-89
•
The output voltage of both types can be set to any value between V
REF
(2.5V) and the corresponding
maximum cathode voltage.
.
Features
•
Programmable Precise Output Voltage from
2.5V to 36V
•
High Stability under Capacitive Load
•
Low Temperature Deviation
•
Can be used in either positive or negative
Voltage reference
•
•
•
•
Low Dynamic Output Impedance: 0.15 to 0.22Ω Typical
Operating Current from 1.0mA to 100mA
Low Output Noise Voltage
RoHS Compliance
Applications
•
•
•
•
•
Charger
Voltage Adapter
Switching Power Supply
Graphic Card
Precision Voltage Reference
TAITRON COMPONENTS INCORPORATED
www.taitroncomponents.com
Tel:
Fax:
(800)-TAITRON (800)-824-8766
(800)-TAITFAX (800)-824-8329
(661)-257-6060
(661)-257-6415
Rev. A/DX 2007-06-04
Page 1 of 14
Shunt Regulator
LM431
Ordering Information
Pin Configuration
Outline: Z
TO-92
Outline: N
SOT-23
Outline: N5
SOT-23-5
Outline: S8
SOP-8
Outline: K
SOT-89
Rev. A/DX 2007-06-04
www.taitroncomponents.com
Page 2 of 14
Shunt Regulator
LM431
Block Diagram
Symbols
Absolute Maximum Ratings (Ta=25° C)
(Full operating ambient temperature range applies unless otherwise noted.)
Symbol
V
KA
I
KA
I
REF
T
J
T
OPR
T
STG
Description
Cathode Voltage
Cathode Current Range (Continuous)
Reference Input Current Range
(Continuous)
Operating Junction Temperature
Operating Temperature Range
Storage Temperature Range
Z:TO-92
N:SOT-23
P
D
Power Dissipation
N5:SOT-23-5
K: SOT-89
S8: SOP-8
Z:TO-92
N:SOT-23
Rth
JA
Package Thermal
Impedance
N5:SOT-23-5
K: SOT-89
S8: SOP-8
-40 ~ 85
700
-
-
800
-
180
-
-
160
-
LM431
LM431A
36
-100 ~ 150
-0.05 ~ 10
150
-40 ~ 125
-65 ~ 150
770
370
370
770
770
150
330
250
50
150
° C/W
mW
LM431B
Unit
V
mA
mA
°C
°C
°C
Rev. A/DX 2007-06-04
www.taitroncomponents.com
Page 3 of 14
Shunt Regulator
LM431
Electrical Characteristics
(T
A
=25ºC, unless otherwise specified)
Symbol
V
REF
Description
Reference Input
Voltage
Reference
Input
Voltage
Deviation
0-70° C
LM431
Min.
2.440
Typ.
2.495
Max.
2.550
Min.
LM431A
Typ.
2.500
Max.
2.520
Min.
LM431B
Typ.
2.500
Max.
2.510
Unit
V
Test
Circuit
Fig.1
Conditions
V
KA
=V
REF
,I
KA
=10mA
2.480
2.490
-
-
-
-
4.8
8
-
4.5
8
mV
Fig.1
(Note1)
V
KA
=V
REF
,I
KA
=10mA
∆V
REF
-
40-85
°C
-
7.0
30
-
4.5
10
-
4.5
10
∆V
KA
=10V~
V
REF
∆V
KA
=36V~
10V
∆V
REF/
∆V
KA
Ratio of Change in
Reference Input
Voltage to Change in
Cathode to Anode
Voltage
Ta=25°
C
Ta=Topr
-
-1.4
-2.7
-
-1.0
-2.7
-
-1.0
-2.7
mV/V
Fig.2
IKA=
10mA
-
-1.0
-2.0
-
-0.5
-2.0
-
-0.5
-2.0
I
REF
Referenc
e Input
Current
-
-
1.8
-
4.0
6.5
-
-
0.7
-
4.0
-
-
-
0.7
-
4.0
µA
-
Fig.2
I
KA
=10mA, R1=10KΩ,
R2=∞
∆I
REF
Reference Input
Current Deviation
-
0.8
2.5
-
0.4
1.2
-
0.4
1.2
µA
Fig.2
I
KA
=10mA, R1=10KΩ,
R2=∞,
-
40 ~ 85° C
V
KA
=V
REF
I
MIN
I
OFF
Z
KA
Min. Cathode Current
For Regulation
Off-State Cathode
Current
Dynamic Impedance
-
0.5
1.0
-
0.4
1.0
-
0.4
1.0
mA
Fig.1
-
-
2.6
0.22
1000
-
-
-
50
0.15
1000
0.5
-
-
50
0.15
1000
0.5
nA
Ω
Fig.3
Fig.1
(Note2)
V
KA
=36V, V
REF
=0V
V
KA
=V
REF
,
I
KA
=1.0~100mA,
f≤1.0KHz
Fig.1- Test Circuit for V
KA
=V
REF
Fig.2- Test Circuit for V
KA
>V
REF
Rev. A/DX 2007-06-04
www.taitroncomponents.com
Page 4 of 14
Shunt Regulator
LM431
Fig.3- Test Circuit for I
OFF
Note1:
Note2:
Rev. A/DX 2007-06-04
www.taitroncomponents.com
Page 5 of 14
