LM431A / LM431B / LM431C — Programmable Shunt Regulator
© 2003 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431A / LM431B / LM431C Rev. 1.1.0 1
December 2012
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 VREF (approximately 2.5 V)
and 36 V with two e xternal resis tors. These dev ices have
a typical dy na mi c ou tpu t imp eda nc e 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
8-SOIC
1. Ref 2. Anode 3. Cathode
1
1
1.Cathode 2.3.6.7.Anode
4.5.NC 8.Ref
LM431A / LM431B / LM431C — Programmable Shunt Regulator
© 2003 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431A / LM431B / LM431C Rev. 1.1.0 2
Ordering Information
Block Diagram
Figure 1. Block Diagram
Part Number Operating
Temperature
Range
Output Voltage
Tolerance Top Mark Package Packing Method
LM431CCZ
-25 ~ +85°C
0.5% LM431CCZ TO-92 Bulk
LM431CCMX LM431CCM 8-SOIC Tape and Reel
LM431BCZX 1% LM431BCZ TO-92 Tape and Reel
LM431BCZXA LM431BCZ TO-92 Ammo
LM431BCMX LM431BCM 8-SOIC Tape and Reel
LM431ACZ 2% LM431ACZ TO-92 Bulk
LM431ACZX LM431ACZ TO-92 Tape and Reel
LM431ACMX LM431ACM 8-SOIC Tape and Reel
LM431CIMX
-40 ~ +85°C
0.5% LM431CIM 8-SOIC Tape and Reel
LM431BIZX 1% LM431BIZ TO-92 Tape and Reel
LM431AIZ 2% LM431AIZ TO-92 Bulk
LM431AIMX LM431AIM 8-SOIC Tape and Reel
CATHODE
ANODE
REFERENCE
CATHODE (K)
ANODE (A)
REFERENCE (R)
2.5 Ref
+
-
LM431A / LM431B / LM431C — Programmable Shunt Regulator
© 2003 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431A / LM431B / LM431C Rev. 1.1.0 3
Absolute Maximum Ratings
Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be opera-
ble above the re co mmen ded operating conditions and stressi ng the part s to these levels is n ot re commended. 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 TA = 25°C unless otherwise noted.
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 Parameter Value Unit
VKA Cathode Voltage 37 V
IKA Cathode Current Range (Continuous) -100 ~ +150 mA
IREF Reference Input Current Range -0.05 ~ +10 mA
PDPower Dissipation
M, Z Suffix Package 770 mW
TOPR Operating Temperature Range LM431xC -25 ~ +85 °C
Operating Temperature Range LM431xI -40 ~ +85 °C
TJJunction Temperature 150 °C
TSTG Storage Temperature Range -65 ~ +150 °C
Symbol Parameter Min. Typ. Max. Unit
VKA Cathode Voltage VRef 36 V
IKA Cathode Current 1.0 100 mA
LM431A / LM431B / LM431C — Programmable Shunt Regulator
© 2003 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431A / LM431B / LM431C Rev. 1.1.0 4
Electrical Characteristics
Values are at TA = 25°C unless otherwise noted.
Notes:
1. LM431xC: TMIN = -25°C, TMAX = +85°C.
LM431xI: TMIN = -40°C, TMAX = +85°C.
Symbol Parameter Conditions LM431A LM431B LM431C Unit
Min. Typ. Max. Min. Typ. Max. Min. Typ. Max.
VREF Reference
Input Voltage VKA = VREF,
IKA = 10 mA 2.450 2.500 2.550 2.470 2.495 2.520 2.482 2.495 2.508 V
ΔVREF/
ΔT
Deviation of
Reference
Input Voltage
Over-
Temperature
VKA = VREF,
IKA =10 mA
TMIN TATMAX(1) 4.5 17.0 4.5 17.0 4.5 17.0 mV
ΔVREF/
ΔVKA
Ratio of
Change in
Reference
Input Voltage
to the
Change in
Cathode
Voltage
IKA =
10 mA
ΔVKA =
10V-VREF -1.0 -2.7 -1.0 -2.7 -1.0 -2.7
mV / V
ΔVKA =
36V-10V -0.5 -2.0 -0.5 -2.0 -0.5 -2.0
IREF Reference
Input Current IKA = 10 mA,
R1 =10 kΩ, R2 = 1.5 4 1.5 4 1.5 4 μA
ΔIREF /
ΔT
Deviation of
Reference
Input Current
Over Full
Temperature
Range
IKA = 10 mA,
R1 = 10 kΩ, R2 =
TA = Full Range 0.4 1.2 0.4 1.2 0.4 1.2 μA
IKA(MIN)
Minimum
Cathode
Cur-
rent for
Regulation
VKA = VREF 0.45 1.0 0.45 1.0 0.45 1.0 mA
IKA(OFF)
Off - Stage
Cathode
Current
VKA = 36 V,
VREF = 0 0.05 1.0 0.05 1.0 0.05 1.0 μA
ZKA
Dynamic
Impedance VKA = VREF,
IKA =1 to 100 mA
f 1.0 kHz 0.15 0.5 0.15 0.5 0.15 0.5 Ω
LM431A / LM431B / LM431C — Programmable Shunt Regulator
© 2003 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431A / LM431B / LM431C Rev. 1.1.0 5
Test Circuits
Figure 2. Test Circuit for VKA= VREF Figure 3. Test Circuit for VKA VREF
Figure 4. Test Circuit for IKA(OFF)
LM431
LM431
LM431
LM431A / LM431B / LM431C — Programmable Shunt Regulator
© 2003 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431A / LM431B / LM431C Rev. 1.1.0 6
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 Volt a ge Amplification vs.
Frequency Figure 10. Pulse Respo nse
LM431A / LM431B / LM431C — Programmable Shunt Regulator
© 2003 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431A / LM431B / LM431C Rev. 1.1.0 7
Typical Performance Characteristics (Continued)
Figure11. Stability Boundary Conditions
100p 1n 10n 100n 1? 10?
0
20
40
60
80
100
120
140
D
C
B
A
A VKA = Vref
B VKA = 5.0 V @ IK = 10mA
C VKA = 10 V @ IK = 10mA
D VKA = 15 V @ IK = 10mA
TA = 25oC
IK, CATHODE CURRENT(mA)
CL, LOAD CAPACITANCE
LM431A / LM431B / LM431C — Programmable Shunt Regulator
© 2003 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431A / LM431B / LM431C Rev. 1.1.0 8
Typical Application
Figure 12. Shunt Regulator Figure 13. Output Control for Thre e-
Terminal Fixed Regulator Figure 14. High-Current Shunt
Regulator
Figure 15. Current Limit or Current Source Figure 16. Constant-Current Sink
VO1R1
R2
-------+



Vref
=
LM431
LM431
VO1R1
R2
-------+



Vref
=
LM431
LM431
LM431
LM431A / LM431B / LM431C — Programmable Shunt Regulator
© 2003 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431A / LM431B / LM431C Rev. 1.1.0 9
Physical Dimensions
Figure 17. 3-Lead, TO-92, Molded, Standard Straight Lead
Package drawings are provided as a service to customers cons idering Fairchild components. Drawings may change in any manner
without notic e. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or
obtain the most recent revision. Package specifications do not expan d the terms of Fairchild’s worldwide terms and condition s, specifically the
warranty therein, which covers Fairchild produ cts.
Always visit Fairchild Semiconduct or’s online packaging are a for the most recent package drawings :
http://www.fairchildsemi.com/packaging/.
D
TO-92 Bulk Type
LM431A / LM431B / LM431C — Programmable Shunt Regulator
© 2003 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431A / LM431B / LM431C Rev. 1.1.0 10
Physical Dimensions (Continued)
Figure 18. 3-Lead, TO-92, Molded, 0.200 in Line Spacing Lead Form
Package drawings are provided as a service to customers cons idering Fairchild components. Drawings may change in any manner
without notic e. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or
obtain the most recent revision. Package specifications do not expan d the terms of Fairchild’s worldwide terms and condition s, specifically the
warranty therein, which covers Fairchild produ cts.
Always visit Fairchild Semiconduct or’s online packaging are a for the most recent package drawings :
http://www.fairchildsemi.com/packaging/.
For current tape an d reel specifications, visit Fair child Semiconductor’s online pac kaging area:
http://www.fairchildsemi.com/products/discrete/pdf/to92_tr.pdf.
D
TO-92 Ammo Type, Tape and Reel Type
LM431A / LM431B / LM431C — Programmable Shunt Regulator
© 2003 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431A / LM431B / LM431C Rev. 1.1.0 11
Physical Dimensions (Continued)
Figure 19. 8-Lead, SOIC, JEDEC MS 0-12, 0.150 inch Narrow Body
Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner
without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or
obtain the most recent revision. Package specificatio ns do not expand t he terms of Fairc hild’s worldwide terms and c onditions, specifically the
warranty therein, which covers Fairchild p roducts.
Always visit Fairchild Semic onductor’s online packag ing area for the most recent package drawings:
http://www.fairchildsemi.com/packaging/.
For current tape an d reel specifications, vis it Fairchild Semicond uctor’s on line packaging area:
http://www.fairchildsemi.com/products/discrete/pdf/soic8_tr.pdf.
8-SOIC
© Fairchild Semiconductor Corporation www.fairchildsemi.com
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Rev. I63
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