©2002 Fairchild Semiconductor Corporation
www.fairchildsemi.com
Rev. 1.0.3
Features
• Programmable Output Voltage to 36 Volts
• Low Dynamic Output Impedance 0.20 Typical
• Sink Curr ent Capabil ity of 1.0 t o 100mA
• Equivalent Full-Range Temperature Coefficient of
50ppm/°C Typical
• Temperature Compensated for Operation Over Full Rated
Operating Temperatur e Ra nge
• Low Output Noise Voltage
• Fast Turn-on Response
Description
The LM431SA/LM431SB/LM431SC are three term inal
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.
SOT-23F
12
3
1. Cathode 2. Ref 3. Anode
1. Ref 2. Anode 3. Cathode
1
SOT-89
Internal Block Diagram
LM431SA/LM431SB/LM431SC
Programmable Shunt Regulator
LM431SA/LM431SB/LM431SC
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 appl y to amb ient temper atur e 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)
MF Suffix Package
ML Suffix Package RθJA 350
220 °C/W
Power Dissipation (Note3,4)
MF Suffix Package
ML Suffix Package PD350
560 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
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
∆
VREF/
∆
TVKA=VREF, IKA=10mA
TMIN≤TA≤TMAX -4.5 17 -4.5 17 -4.5 17 mV
Ratio of
Change in
Reference
Input Voltage
∆
VREF/
∆
VKA IKA
=10mA
∆
VKA=10V-
VREF - -1.0 -2.7 - -1.0 -2.7 - -1.0 -2.7
mV/V
to the Change
in Cathode
Voltage
∆
VKA=36V-
10V - -0.5 -2.0 - -0.5 -2.0 - -0.5 -2.0
Reference
Input Current IREF IKA=10mA,
R1=10KΩ,R2=∞-1.54 -1.54 -1.54
µ
A
Deviation of
Reference
Input Current
Over Full
Temperature
Range
∆
IREF/
∆
T
IKA=10mA,
R1=10KΩ,R2=∞
TA =Full Range -0.4 1.2 -0.4 1.2 -0.4 1.2
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 10 0m A ,f ≥1.0kHz - 0.15 0.5 - 0.15 0.5 - 0.15 0.5 Ω
LM431SA/LM431SB/LM431SC
4
Test Circuits
Figure 1. Test Circ uit fo r VKA=VREF Figure 2. Test Circuit for VKA≥
≥≥
≥VREF
LM431S
LM431S
LM431S
Figure 3. Test Circuit for lKA(OFF)
LM431SA/LM431SB/LM431SC
5
Typical Performance Cha racteristics
-2 -1 0 1 2 3
-100
-50
0
50
100
150
VKA = VREF
TA = 25oC
IK, Cathode Current (mA)
VKA, Cathode Voltage (V)
-50 -25 0 25 50 75 100 125
0.000
0.025
0.050
0.075
0.100
Ioff, Off-State Cathode 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)
-10123
-200
0
200
400
600
800
IKA(MIN)
VKA = VREF
TA = 25oC
IKA, CATHODE CURRENT (uA)
VKA, CATHODE VOLTAGE (V)
-50-25 0 25 50 75100125
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Iref, Reference Inp ut Curre nt (uA)
TA, Ambient Temperature (oC)
048121620
0
1
2
3
4
5
6
TA=25oC
OUTPUT
INPUT
Voltage Swing (V)
Time (us)
Figure 4. Cathode Current vs. Cathode Vol tage Figure 5. Cathode Current vs. Cathode Vo ltage
Figure 6. OFF-State Cathode Current vs.
Ambient Te mperature Figure7. Reference Input Current vs.
Ambie nt Temper ature
Figure 8. Small Signal Voltage Amplification vs. Frequency Figure 9. Pulse Resp onse
LM431SA/LM431SB/LM431SC
6
Typica l Perfo rmance Characteristics (Continued)
100p 1n 10n 100n 1µ 10µ
0
20
40
60
80
100
120
140
B
A
A VKA = Vref
B VKA = 5.0 V @ IK = 10mA
TA = 25oC
IK, CATHODE CURRENT(mA)
CL, LOAD CAPACITANCE
Figure 10. Stability Boundary Conditions Figure 11. Anode-Reference Diode Curve
Figur e 12. Reference-Cathode Di ode Cur ve
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-R ef. 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
7
Typical Application
VO1R1
R2
-------+
Vref
=
LM431S
VOVref 1R1
R2
-------+
=
LM431S
LM7805/MC7805
VO1R1
R2
-------+
Vref
=
LM431S
LM431S LM431S
Figure 13. Shunt Regulator Figure 14. Output Control for
-Three-Termianl Fixed Regulator Figure 15. Hi gh Current Shunt Regulator
Figure 16. Current Limit or Current Sour ce Fi gu re 17. Cons tant-Cu rrent Sink
LM431SA/LM431SB/LM431SC
8
Mechanical Dimensions
Package Dimensions in millimeters
Marking
SOT-23F
43A 43B 43C
2% tolerance 1% tolerance 0.5% tolerance
LM431SA/LM431SB/LM431SC
9
Mechanical Dimensions (Continued)
Package Dimensions in millimeters
Marking
SOT-89
0.40
±0.10
2.50
±0.20
(0.50)
(0.40)
4.10
±0.20
0.40
+0.10
–0.05
0.50
±0.10
1.65
±0.10
4.50
±0.20
1.50
±0.20
C0.2
1.50 TYP 1.50 TYP
(1.10)
43A
2% tolerance 1% tolerance 0.5% tolerance
43B 43C
LM431SA/LM431SB/LM431SC
11/14/02 0.0m 001
Stock#DSxxxxxxxx
2002 Fairchild Semicond uctor Corporation
LIFE SU PP ORT POL ICY
FAIRCHILD’S PRODUCTS AR E NOT AUTHORIZED FOR USE AS C RITICAL COMPONENTS I N LIFE S UPPORT DEVICE S
OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR
CORPORA TION. As used he rein :
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 critical component in any component of a life support
device or syst em who se failure to perform can be
reasonably expected to cause the failure of the life support
device or system, or to affect its safety or effec tiv ene ss.
www.fairchildsemi.com
DISCLAIMER
FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY
PRO DUCTS HEREIN TO IMPROVE RELIABILITY, FUN C TION OR DESIGN . FAIRCHILD DO ES 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 RIG HTS, NOR THE RIGHTS OF OTHERS.
Ordering Information
Product Number Output Voltage Tolerance Package Operating Temp erature
LM431SCCML 0.5% SOT-89
-25 ~ +85°C
LM431SCCMF SOT-23F
LM431SBCML 1% SOT-89
LM431SBCMF SOT-23F
LM431SACML 2% SOT-89
LM431SACMF SOT-23F
