©2003 Fairchild Semiconductor Corporation
www.fairchildsemi.com
Rev. 1.0.4
Features
• Programmable Output Voltage to 36 Volts
• Low Dynamic Output Impedance 0.20 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 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 V
REF
(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-o n 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 R egulator
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 apply to ambient te mperat ure at 25
°
C
4. Power dissipation calculation: PD = (TJ - TA)/
R
θJA
Recommended Operating Conditions
Parameter Symbol Value Unit
Cathode Voltage V
KA
37 V
Cathode current Range (Continuous) I
KA
-100 ~ +150 mA
Reference Input Current Range I
REF
-0.05 ~ +10 mA
Thermal Resistance Junction-Air (Note1,2)
MF Suffix Package
ML Suffix Package R
θJA
350
220 °C/W
Power Dissipation (Note3,4)
MF Suffix Package
ML Suffix Package P
D
350
560 mW
Junction Temperature T
J
150 °C
Operating Temperature Range T
OPR
-25 ~ +85 °C
Storage Temperature Range T
STG
-65 ~ +150 °C
Parameter Symbol Min. Typ. Max. Unit
Cathode Voltage V
KA
V
REF
-36V
Cathode Current I
KA
1.0 - 100 mA
LM431SA/LM431SB/LM431SC
3
Electrical Characteristics
(T
A
= +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 Characteristics
-2-10123
-100
-50
0
50
100
150
V
KA
= V
REF
T
A
= 25
o
C
I
K
, Cathode Cur rent (m A)
V
KA
, Cathode Voltag e (V)
-50 -25 0 25 50 75 100 125
0.000
0.025
0.050
0.075
0.100
I
off
, Off-State Cathode Current (uA)
T
A
, Ambient Temperature (
o
C)
1k 10k 100k 1M 10M
-10
0
10
20
30
40
50
60
T
A
= 25
o
C
I
KA
= 10mA
Open Loop Voltage Gain (dB)
Frequency (Hz)
-10123
-200
0
200
400
600
800
I
KA(MIN)
V
KA
= V
REF
T
A
= 25
o
C
I
KA
, CATHODE CURRENT (uA)
V
KA
, CATHODE VOLTAGE (V)
-50 -25 0 25 50 75 100 125
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
I
ref
, Reference Input Current (uA)
T
A
, Ambient Temperature (
o
C)
048121620
0
1
2
3
4
5
6
T
A
=25
o
C
OUTPUT
INPUT
Voltage Swing (V)
Time (us)
Figure 4. Cat hode Current vs. Cathode Voltage Figur e 5. Cath ode C u rrent vs. Cathode Voltage
Figur e 6. OFF-State Cathode Current vs.
Ambient Te mperat ure Figure7. Reference Input Current vs.
Ambie nt Te mp er atu r e
Figure 8. Small Signal Voltage Amplification vs. Frequency Figur e 9. Pulse Re sp on se
LM431SA/LM431SB/LM431SC
6
Typical Performance Characteristics
(Continued)
100p 1n 10n 100n 1
!
10
!
0
20
40
60
80
100
120
140
B
A
A V
KA
= Vref
B V
KA
= 5.0 V @ I
K
= 10
mA
T
A
= 25
o
C
I
K
, CATHODE CURRENT(mA)
C
L
, LOAD CAPACITANCE
Figure 10. Stability Boundary Conditions Figure 11. Anode-Reference Diode Curve
Figur e 12. Reference -Cathode Diode Curve
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. Vol tag e(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
V
O
1R
1
R
2
-------+
V
ref
=
LM431S
V
O
V
ref
1R
1
R
2
-------+
=
LM431S
LM7805/MC7805
V
O
1R
1
R
2
-------+
V
ref
=
LM431S
LM431S LM431S
Figur e 13
.
Shunt Regulator Figure 14
.
Output Control for
-Three-Termianl Fixed Regulator Figure 15. High Current Shunt Regul ator
Figure 16. Current Limit or C urrent Source Fi gure 17. Co nstant-Curr e n t Sink
LM431SA/LM431SB/LM431SC
8
Mechanic al Dime nsions
Package Dimensions in millimeters
Marking
SOT-23F
43A 43B 43C
2% tolerance 1% tolerance 0.5% tolerance
LM431SA/LM431SB/LM431SC
9
Mechanic al Dime nsions
(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
8/4/03 0.0m 001
Stock#DSxxxxxxxx
2003 Fairchild Semiconductor Corporation
LIFE SU PP ORT POL ICY
FAIRCHILD’ S PRODUCTS ARE NOT AUTHORIZ ED FOR USE AS CRI TICAL C OMPONENTS IN LIFE SUPP ORT DEVI CES
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 fai lure to pe rform 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 MA KE CHANGES WITHOUT FURTHER NOTICE TO ANY
PRO DUCTS HEREIN TO IMPROVE RELIABILITY, FUN CTION OR DESIG N. FAIRCHILD DO ES NOT ASSUME ANY
LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER
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Ordering Information
Product Number Output Voltage Tolerance Package Operating Temperature
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
