©2011 Fairchild Semiconductor Corporation
www.fairchildsemi.com
Rev. 1.0.8
Features
• Programmable Output Voltage to 36 Volts
• Low Dynamic Outpu t Impedance 0.2Ω Typical
• Sink Current Capability of 1.0 to 100mA
• Equivalent Full-Range Temperature Coefficient of
50ppm/°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 output
adjustable regulators with thermal stability over operating
temperature range. The output voltage can be set any value
between VREF (approximately 2.5 volts) and 36 volts with
two external resistors. These devices have a typical dynamic
output impedance of 0.2Ω. Active output circuit provides a
sharp turn-on characteristic, making these devices excellent
replacement for Zener Diodes in many applications.
TO-92
8-DIP 8-SOP
1. Ref 2. Anode 3. Cathode
1
11
1.Cathode 2.3.6.7.Anode
4.5.NC 8.Ref
1.Cathode 2.3.4.5.7.NC
6.Anode 8.Ref
Internal Block Diagram
CATHODE
ANODE
REFERENCE
CATHODE (K)
ANODE (A)
REFERENCE (R)
2.5 Vref
+
-
LM431A/LM431B/LM431C
Programmable Shunt Regulator
LM431A/LM431B/LM431C
2
Absolute Maximum Ratings
(Operating temperature range applies unless otherwise specified.)
Recommended Operating Conditions
Parameter Symbol Value Unit
Cathode Volt ag e VKA 37 V
Cathode Current Range (Continuous) IKA -100 ~ +150 mA
Reference Input Current Range IREF -0.05 ~ +10 mA
Power Dissipation
M, Z Suffix Package
N Suffix Package PD770
1000 mW
Operating Temperature Range
LM431xC TOPR -25 ~ +85 °C
LM431xI -40 ~ +85 °C
Junction Temperature TJ150 °C
Storage Temperature Range TSTG -65 ~ +150 °C
Parameter Symbol Min Typ Max Unit
Cathode Volt ag e VKA VREF -36V
Cathode Curr en t IKA 1.0 - 100 mA
LM431A/LM431B/LM431C
3
Electrical Characteristics
(TA = +25°C, unless otherwise specified)
Note1
• LM431XC : TMIN = -25 °C, TMAX = +85°C
• LM431XI : TMIN = -40°C, TMAX = +85°C
Parameter Symbol Conditions LM431A LM431B LM431C Unit
Min. Typ. Max. Min. Typ. Max. Min. Typ. Max.
Reference
Input Voltage VREF VKA = VREF, IKA =10mA 2.450 2.500 2.550 2.470 2.495 2.520 2.482 2.495 2.508 V
Deviation of
Reference
Input Voltage
Over-
Temperature
ΔVREF/
ΔTVKA=VREF, IKA=10mA
TMIN≤TA≤TMAX - 4.5 17 - 4.5 17 - 4.5 17 mV
Ratio of
Change in
Reference
Input Voltage
to the Change
in Cathode
Voltage
ΔVREF/
ΔVKA IKA
=10mA
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
Reference
Input Current IREF IKA=10mA,
R1=10kΩ,R2=∞- 1.5 4 - 1.5 4 - 1.5 4 μA
Deviation of
Reference
Input Current
Over Full
Temperature
Range
ΔIREF/ΔT
IKA=10mA,
R1=10kΩ,R2=∞
TA =Full Range - 0.4 1.2 - 0.4 1.2 - 0.4 1.2 μA
Minimum
Cathode Cur-
rent for
Regulation
IKA(MIN) VKA=VREF - 0.45 1.0 - 0.45 1.0 - 0.45 1.0 mA
Off - Stage
Cathode
Current IKA(OFF) VKA=36V,
VREF=0 - 0.05 1.0 - 0.05 1.0 - 0.05 1.0 μA
Dynamic
Impedance ZKA VKA=VREF,
IKA=1 to 100mA
f ≥1.0kHz - 0.15 0.5 - 0.15 0.5 - 0.15 0.5 Ω
LM431A/LM431B/LM431C
4
Test Circuits
Figure 1. Test Circuit for VKA=VREF Figure 2. Test Circuit for VKA≥VREF
LM431A/B/C
LM431A/B/C
LM431A/B/C
Figure 3. Test Circuit for lKA(OFF)
LM431A/LM431B/LM431C
5
Typical Performance Characteristics
Figure 4. Cathode Current vs. Cath ode Voltage Figure 5. Cathode Current vs. Cathode Voltage
Figure 6. Change In Reference Input Voltage vs.
Cathode Voltage Figure7. Dynamic Impedance Frequency
Figure 8. Small Signal Voltage Amplification vs. Frequency Figure 9. Pulse Response
LM431A/LM431B/LM431C
6
Typical Performance Characteristics (Continued)
100p 1n 10n 100n 1ٛ10
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
Figure 10. Stability Boundary Conditions
stable stable
LM431A/LM431B/LM431C
7
Typical Application
VO1R1
R2
-------
+
⎝⎠
⎛⎞
Vref
=
LM431A/B/C
VOVref 1R1
R2
-------
+
⎝⎠
⎛⎞
=
LM431A/B/C
LM7805/MC7805
VO1R1
R2
-------
+
⎝⎠
⎛⎞
Vref
=
LM431A/B/C
LM431A/B/C LM431A/B/C
Figure 11. Shunt Regulator Figure 12 . Output Contro l for
minal Fixed Reg ulatorThree- Ter--Figure 13. High Current Shunt Regulato r
Figure 14. Current Limit or Current Source Figure 15. Constan t-Current Sink
LM431A/LM431B/LM431C
8
Mechanical Dimensions
Package Dimensions in millimeters
0.46
±0.10
1.27TYP
(R2.29)
3.86MAX
[1.27
±0.20
]1.27TYP
[1.27
±0.20
]
3.60
±0.20
14.47
±0.40
1
.02
±0.10
(0.25) 4.58
±0.20
4.58
+0.25
–0.15
0.38
+0.1
0
–0.0
5
0.38
+0.10
–0.05
TO-92
LM431A/LM431B/LM431C
9
Mechanical Dimensions (Continued)
Package Dimensions in millimeters
4.92 ±0.20
0.194 ±0.008
0.41 ±0.10
0.016 ±0.004
1.27
0.050
5.72
0.225
1.55 ±0.20
0.061 ±0.008
0.1~0.25
0.004~0.001
6.00 ±0.30
0.236 ±0.012
3.95 ±0.20
0.156 ±0.008
0.50 ±0.20
0.020 ±0.008
5.13
0.202 MAX
#1
#4 #5
0~8°
#8
0.56
0.022
()
1.80
0.071
MAX0.10
MAX0.004
MAX
MIN
+
0.10
-0.05
0.15+
0.004
-0.002
0.006
8-SOP
LM431A/LM431B/LM431C
10
Mechanical Dimensions (Continued)
Package Dimensions in millimeters
8-DIP
6.40 ±0.20
3.30 ±0.30
0.130 ±0.012
3.40 ±0.20
0.134 ±0.008
#
1
#
4#5
#8
0.252 ±0.008
9.20 ±0.20
0.79
2.54
0.100
0.031
(
)
0.46 ±0.10
0.018 ±0.004
0.060 ±0.004
1.524 ±0.10
0.362 ±0.008
9.60
0.378 MAX
5.08
0.200
0.33
0.013
7.62
0~15°
0.300
MAX
MIN
0.25
+0.10
–0.05
0.010
+0.004
–0.002
LM431A/LM431B/LM431C
11
Ordering Information
Product Number Output Voltage Tolerance Package Operating Temperature
LM431CCZ 0.5% TO-92
-25 ~ +85°C
LM431CCM 8-SOP
LM431BCZ 1% TO-92
LM431BCM 8-SOP
LM431ACN 2% 8-DIP
LM431ACZ TO-92
LM431ACM 8-SOP
LM431CIZ 0.5% TO-92
-40 ~ +85°C
LM431CIM 8-SOP
LM431BIZ 1% TO-92
LM431BIM 8-SOP
LM431AIZ 2% TO-92
LM431AIM 8-SOP
LM431A/LM431B/LM431C
2/16/11 0.0m 001
Stock#DS400300
© 2011 Fairchild Semiconductor Corporation
LIFE SUPPORT POLICY
FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES
OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR
CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body,
or (b) support or sustain life, and (c) whose failure to
perform when properly used in accordance with
instructions for use provided in the labeling, can be
reasonably expected to result in a significant injury of the
user.
2. A critica l component in any component of a life support
device or system whose failure to perform can be
reasonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
www.fairchildsemi.com
DISCLAIMER
FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY
PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY
LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER
DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.
