LM431SA/LM431SB/LM431SC — Programmable Shunt Regulator
© 2012 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431SA/LM431SB/LM431SC Rev. 1.2.0 1
June 2012
LM431SA/LM431SB/LM431SC
Programmable Shunt Regulator
Features
• Programmable Output Vo ltage to 36 Volts
• Low Dynamic Output 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 Rang e
• Low Output Noise Voltage
• Fast Turn-on Response
Internal Block Diagram
1. Ref 2. Anode 3. Cathode
1
SOT-89 SOT-23F
12
3
1. Cathode 2. Ref 3. Anode
SOT-23
12
3
M32 - 1. Ref 2. Cathode 3. Anode
M3 - 1. Cathode 2. Ref 3. Anode
+
-
Description
The LM431SA/LM431SB/LM431SC 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 outp ut impedance of 0.2Ω. Active
output circuit provides a sharp turn-on characteristic,
making these devices excellent replacement for Zener
Diodes in many applications.
LM431SA/LM431SB/LM431SC — Programmable Shunt Regulator
© 2012 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431SA/LM431SB/LM431SC Rev. 1.2.0 2
Absolute Maximum Ratings
(Operating temperature range applies unless otherwise specified.)
Note:
1. Thermal resistance test board
Size: 76.2mm * 114.3mm * 1.6mm (1S0P)
JEDEC Standard: JESD51-3, JESD51-7
2. Assume no ambient airflow.
3. TJMAX = 150°C, Ratings apply to ambient temperature at 25°C
4. Power dissipation calculation: PD = (TJ - TA)/RθJA
Recommended Operating Conditions
Parameter Symbol Value Unit
Cathode Voltage VKA 37 V
Cathode current Range (Continuous) IKA -100 ~ +150 mA
Reference Input Current Range IREF -0.05 ~ +10 mA
Thermal Resistance Junction-Air (Note1,2)
ML Suffix Package (SOT-89)
MF Suffix Package (SOT-23F)
M32, M3 Suffix Package (SOT-23)
RθJA 220
350
400
°C/W
Power Dissipation (Note3,4)
ML Suffix Package (SOT-89)
MF Suffix Package (SOT-23F)
M32, M3 Suffix Package (SOT-23)
PD560
350
310
mW
Junction Temperature TJ150 °C
Operating Temperature Range TOPR -25 ~ +85 °C
Storage Temperature Range TSTG -65 ~ +150 °C
Parameter Symbol Min. Typ. Max. Unit
Cathode Voltage VKA VREF -36V
Cathode Current IKA 1.0 - 100 mA
LM431SA/LM431SB/LM431SC — Programmable Shunt Regulator
© 2012 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431SA/LM431SB/LM431SC Rev. 1.2.0 3
Electrical Characteristics
(TA = +25°C, unless otherwise specified )
Note1
TMIN = -25°C, TMAX = +85°C
Parameter Symbol Conditions LM431SA LM431SB LM431SC 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
Δ
VREF/
Δ
TVKA=VREF,
IKA=10mA
TMIN≤TA≤TMAX
SOT-89
SOT-23F - 4.5 17 - 4.5 17 - 4.5 17 mV
SOT-23 - 6.6 24 - 6.6 24 - 6.6 24 mV
Ratio of
Change in
Reference
Input Voltage
to the Change
in Cathode
Voltage
Δ
VREF/
Δ
VKA IKA =10mA
Δ
VKA=10V
-VREF - -1.0 -2.7 - -1.0 -2.7 - -1.0 -2.7
mV/V
Δ
VKA=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
μ
A
Deviation of
Reference
Input Current
Over Full
Temperature
Range
Δ
IREF/
Δ
T
IKA=10mA,
R1=10KΩ,
R2=∞,
TA =Full Range
SOT-89
SOT-23F - 0.4 1.2 - 0.4 1.2 - 0.4 1.2
μ
A
SOT-23 - 0.8 2.0 - 0.8 2.0 - 0.8 2.0
μ
A
Minimum
Cathode
Current 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
μ
A
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
LM431SA/LM431SB/LM431SC — Programmable Shunt Regulator
© 2012 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431SA/LM431SB/LM431SC Rev. 1.2.0 4
Test Circuits
Figure 1. Test Circuit for VKA=VREF Figure 2. Test Circuit for VKA≥VREF
LM431S
LM431S
LM431S
Figure 3. Test Circuit for lKA(OFF)
LM431SA/LM431SB/LM431SC — Programmable Shunt Regulator
© 2012 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431SA/LM431SB/LM431SC Rev. 1.2.0 5
Typical Performance Characteristics
Figure 4. Cathode Current vs. Cathod e Voltage Figure 5. Cathode Current vs. Cathode Volt age
Figure 6. OFF-State Cathode Current vs.
Ambient Temperature Figure 7. Reference Input Current vs.
Ambient Temperature
Figure 8. Small Signal Voltage Amplification vs.
Frequency Figure 9. Pulse Response
-2-10123
-100
-50
0
50
100
150
VKA = VREF
TA = 25oC
IK, Cathode Current (mA)
VKA, Cathode Voltage (V) -10123
-200
0
200
400
600
800
IKA(MIN)
VKA = VREF
TA = 25oC
IKA, CATHOD E CURRENT (uA)
VKA, CATHODE VOLTAGE (V)
-50 -25 0 25 50 75 100 125 150
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0.20
Ioff, Off-State Cathode Current (uA)
TA, Am bient Temperature (oC)
-50 -25 0 25 50 75 100 125
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Iref, Reference Input Current (uA)
TA, Ambient Temperature (oC)
1k 10k 100k 1M 10M
-10
0
10
20
30
40
50
60
TA = 25oC
IKA = 10mA
Open Loop Voltage Gain (dB)
Frequency (Hz)
0 4 8 121620
0
1
2
3
4
5
6
TA=25oC
OUTPUT
INPUT
Voltage Swing (V)
Time (us)
LM431SA/LM431SB/LM431SC — Programmable Shunt Regulator
© 2012 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431SA/LM431SB/LM431SC Rev. 1.2.0 6
Typical Performance Characteristics (Continued)
Figure 10. Stability Boundary Conditions Figure 11. Anode-Reference Diode Curve
Figure 12. Reference-Cathode Diode Curve
100p 1n 10n 100n 1
ٛ
10
ٛ
0
20
40
60
80
100
120
140
B
A
A VKA = Vref
B VKA = 5.0 V @ IK = 10mA
TA = 25oC
I
K
, CATHODE CURRENT(mA)
C
L
, LOAD CAPACITANCE
stable
stable
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
0
1
2
3
4
5
Current(mA)
Anode-Ref. Voltage(V)
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
0
1
2
3
4
5
Current(mA)
Ref.-Cathode Voltage(V)
LM431SA/LM431SB/LM431SC — Programmable Shunt Regulator
© 2012 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431SA/LM431SB/LM431SC Rev. 1.2.0 7
Typical Application
VO1
R1
R2
-------
+
⎝⎠
⎛⎞
Vref
=
LM431S
VOVref 1
R1
R2
-------
+
⎝⎠
⎛⎞
=
LM431S
LM7805/MC7805
VO1
R1
R2
-------
+
⎝⎠
⎛⎞
Vref
=
LM431S
LM431S LM431S
Figure 13. Shunt Regulator Figure 14. Output Control for
Three-Terminal Fixed Regulator
Figure 15. High Current Shunt Regulator
Figure 16. Current Limit or Current Source Figure 17. Constant-Current Sink
LM431SA/LM431SB/LM431SC — Programmable Shunt Regulator
© 2012 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431SA/LM431SB/LM431SC Rev. 1.2.0 8
Mechanical Dimensions
Package Dimensions in millimeters
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43A
2% tolerance 1% tolerance 0.5% tolerance
43B 43C
LM431SA/LM431SB/LM431SC — Programmable Shunt Regulator
© 2012 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431SA/LM431SB/LM431SC Rev. 1.2.0 9
Mechanical Dimensions (Continued)
Package Dimensions in millimeters
Marking
SOT-23F
43A 43B 43C
2% tolerance 1% tolerance 0.5% tolerance
LM431SA/LM431SB/LM431SC — Programmable Shunt Regulator
© 2012 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431SA/LM431SB/LM431SC Rev. 1.2.0 10
Mechanical Dimensions (Continued)
Package Dimensions in millimeters
Marking
SOT-23
43G 43H 43J
2% tolerance 1% tolerance 0.5% tolerance
43L 43M 43N
2% tolerance 1% tolerance 0.5% tolerance
M32 -
M3 -
LM431SA/LM431SB/LM431SC — Programmable Shunt Regulator
© 2012 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM431SA/LM431SB/LM431SC Rev. 1.2.0 11
Ordering Information
Note : X suffix means " Tape and Reel " packing.
Product Number Output Voltage Tolerance Operating Temperature Package Packing Method
LM431SCCMLX
0.5%
-25 ~ +85°C
SOT-89
Tape an d Reel
LM431SCCMFX SOT-23F
LM431SCCM32X SOT-23
LM431SCCM3X SOT-23
LM431SBCMLX
1%
SOT-89
LM431SBCMFX SOT-23F
LM431SBCM32X SOT-23
LM431SBCM3X SOT-23
LM431SACMLX
2%
SOT-89
LM431SACMFX SOT-23F
LM431SACM32X SOT-23
LM431SACM3X SOT-23
© Fairchild Semiconductor Corporation www.fairchildsemi.com
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Rev. I61