LM431A / LM431B / LM431C — Programmable Shunt Regulator
June 2013
LM431A / LM431B / LM431C
Programmable Shunt Regulator
Features
•
•
•
•
Programmable Output Voltage to 36 V
Low Dynamic Output Impedance: 0.2
Ω
(Typical)
Sink Current Capability: 1.0 to 100 mA
Equivalent Full-Range Temperature Coefficient of
50 ppm/°C (Typical)
• Temperature Compensated for Operation Over Full
Rated Operating Temperature Range
• Low Output Noise Voltage
• Fast Turn-on Response
Description
The LM431A / LM431B / LM431C are three-terminal out-
put adjustable regulators with thermal stability over the
full operating temperature range. The output voltage can
be set to any value between V
REF
(approximately 2.5 V)
and 36 V with two external resistors. These devices have
a typical dynamic output impedance of 0.2
Ω.
Active out-
put circuit provides a sharp turn-on characteristic, mak-
ing these devices excellent replacements for Zener
diodes in many applications.
TO-92
1
1. Ref 2. Anode 3. Cathode
8-SOIC
1
1.Cathode 2.3.6.7.Anode
4.5.NC 8.Ref
Ordering Information
Part Number
LM431CCZ
LM431CCMX
LM431BCZX
LM431BCZXA
LM431BCMX
LM431ACZ
LM431ACZX
LM431ACMX
LM431CIMX
LM431BIZX
LM431AIZ
LM431AIMX
-40 ~ +85
°
C
0.5%
1%
2%
2%
-25 ~ +85
°
C
1%
Operating
Output Voltage
Temperature
Tolerance
Range
0.5%
Top Mark
LM431CCZ
LM431CCM
LM431BCZ
LM431BCZ
LM431BCM
LM431ACZ
LM431ACZ
LM431ACM
LM431CIM
LM431BIZ
LM431AIZ
LM431AIM
Package
TO-92
8-SOIC
TO-92
TO-92
8-SOIC
TO-92
TO-92
8-SOIC
8-SOIC
TO-92
TO-92
8-SOIC
Packing Method
Bulk
Tape and Reel
Tape and Reel
Ammo
Tape and Reel
Bulk
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
Bulk
Tape and Reel
© 2003 Fairchild Semiconductor Corporation
LM431A / LM431B / LM431C Rev. 1.2.0
www.fairchildsemi.com
1
LM431A / LM431B / LM431C — Programmable Shunt Regulator
Block Diagram
REFERENCE
+
-
2.5 Ref
CATHODE
ANODE
CATHODE (K)
REFERENCE (R)
ANODE (A)
Figure 1. Block Diagram
Absolute Maximum Ratings
Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be opera-
ble above the recommended operating conditions and stressing the parts to these levels is not recommended. In addi-
tion, extended exposure to stresses above the recommended operating conditions may affect device reliability. The
absolute maximum ratings are stress ratings only. Values are at T
A
= 25°C unless otherwise noted.
Symbol
V
KA
I
KA
I
REF
P
D
R
θjA
T
OPR
T
J
T
STG
Cathode Voltage
Parameter
Cathode Current Range (Continuous)
Reference Input Current Range
Power Dissipation
TO-92, 8-SOIC Packages
Thermal Resistance, Junction to Ambient
TO-92, 8-SOIC Packages
Operating Temperature Range LM431xC
Operating Temperature Range LM431xI
Junction Temperature
Storage Temperature Range
Value
37
-100 ~ +150
-0.05 ~ +10
770
160
-25 ~ +85
-40 ~ +85
150
-65 ~ +150
Unit
V
mA
mA
mW
°C/W
°C
°C
°C
°C
Recommended Operating Conditions
The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended
operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not
recommend exceeding them or designing to Absolute Maximum Ratings.
Symbol
V
KA
I
KA
Parameter
Cathode Voltage
Cathode Current
Min.
V
Ref
1.0
Max.
36
100
Unit
V
mA
© 2003 Fairchild Semiconductor Corporation
LM431A / LM431B / LM431C Rev. 1.2.0
www.fairchildsemi.com
2
LM431A / LM431B / LM431C — Programmable Shunt Regulator
Electrical Characteristics
Values are at T
A
= 25°C unless otherwise noted.
Symbol Parameter
V
REF
Conditions
LM431A
LM431B
LM431C
Min. Typ. Max. Min. Typ. Max. Min. Typ. Max.
2.450 2.500 2.550 2.470 2.495 2.520 2.482 2.495 2.508
Unit
V
Reference
V
KA
= V
REF
,
Input Voltage I
KA
= 10 mA
Deviation of
Reference
Input Voltage
Over-
Temperature
V
KA
= V
REF
,
I
KA
=10 mA
T
MIN
≤
T
A
≤
T
MAX
(1)
ΔV
KA
=
10V-V
REF
ΔV
REF
/
ΔT
4.5
17.0
4.5
17.0
4.5
17.0
mV
ΔV
REF
/
ΔV
KA
Ratio of
Change in
Reference
Input Voltage I
KA
=
10 mA
to the
Change in
Cathode
Voltage
-1.0
-2.7
-1.0
-2.7
-1.0
-2.7
ΔV
KA
=
36V-10V
mV / V
-0.5
-2.0
-0.5
-2.0
-0.5
-2.0
I
REF
Reference
I
KA
= 10 mA,
Input Current R1 =10 kΩ, R2 =
∞
Deviation of
Reference
Input Current
Over Full
Temperature
Range
Minimum
Cathode
Cur-rent for
Regulation
Off - Stage
Cathode
Current
Dynamic
Impedance
I
KA
= 10 mA,
R1 = 10 kΩ, R2 =
∞
T
A
= Full Range
1.5
4.0
1.5
4.0
1.5
4.0
μ
A
ΔI
REF
/
ΔT
0.4
1.2
0.4
1.2
0.4
1.2
μ
A
I
KA(MIN)
V
KA
= V
REF
0.45
1.00
0.45
1.00
0.45
1.00
mA
I
KA(OFF)
V
KA
= 36 V,
V
REF
= 0
V
KA
= V
REF
,
I
KA
=1 to 100 mA
f
≥
1.0 kHz
0.05
1.00
0.05
1.00
0.05
1.00
μ
A
Z
KA
Note:
0.15
0.50
0.15
0.50
0.15
0.50
Ω
1.
LM431xC: T
MIN
= -25°C, T
MAX
= +85°C.
LM431xI: T
MIN
= -40°C, T
MAX
= +85°C.
© 2003 Fairchild Semiconductor Corporation
LM431A / LM431B / LM431C Rev. 1.2.0
www.fairchildsemi.com
3
LM431A / LM431B / LM431C — Programmable Shunt Regulator
Test Circuits
LM431
LM431
Figure 2. Test Circuit for V
KA
= V
REF
Figure 3. Test Circuit for V
KA
≥
V
REF
LM431
Figure 4. Test Circuit for I
KA(OFF)
© 2003 Fairchild Semiconductor Corporation
LM431A / LM431B / LM431C Rev. 1.2.0
www.fairchildsemi.com
4
LM431A / LM431B / LM431C — Programmable Shunt Regulator
Typical Performance Characteristics
Figure 5. Cathode Current vs. Cathode Voltage
Figure 6. Cathode Current vs. Cathode Voltage
Figure 7. Change In Reference Input Voltage vs.
Cathode Voltage
Figure 8. Dynamic Impedance Frequency
Figure 9. Small Signal Voltage Amplification vs.
Frequency
Figure 10. Pulse Response
© 2003 Fairchild Semiconductor Corporation
LM431A / LM431B / LM431C Rev. 1.2.0
www.fairchildsemi.com
5
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