©2002 Fairchild Semiconductor Corporation
www.fairchildsemi.com
Rev. 1.0.6
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 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 V
REF
(approximately 2.5 volts) and 36 volts with
two external resistors. These devices have a typical dynamic
output impedance of 0.2
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
1
1
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 Voltage
V
KA
37
V
Cathode Current Range (Continuous)
I
KA
-100 ~ +150
mA
Reference Input Current Range
I
REF
0.05 ~ +10
mA
Power Dissipation
M, Z Suffix Package
N Suffix Package
P
D
770
1000
mW
Operating Temperature Range
LM431xC
T
OPR
-25 ~ +85
°
C
LM431xI
-40 ~ +85
°
C
Junction Temperature
T
J
150
°
C
Storage Temperature Range
T
STG
-65 ~ +150
°
C
Parameter
Symbol
Min
Typ
Max
Unit
Cathode Voltage
V
KA
V
REF
-
36
V
Cathode Current
I
KA
1.0
-
100
mA
LM431A/LM431B/LM431C
3
Electrical Characteristics
(T
A
= +25
°
C, unless otherwise specified)
Note1
· LM431
X
C : T
MIN
= -25
°
C, T
MAX
= +85
°
C
· LM431
X
I : T
MIN
= -40
°
C, T
MAX
= +85
°
C
Parameter
Symbol
Conditions
LM431A
LM431B
LM431C
Unit
Min. Typ. Max. Min. Typ. Max. Min. Typ. Max.
Reference
Input Voltage
V
REF
V
KA
= V
REF
, I
KA
=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
V
REF
/
T
V
KA
=V
REF
, I
KA
=10mA
T
MIN
T
A
T
MAX
-
4.5
17
-
4.5
17
-
4.5
17
mV
Ratio of
Change in
Reference
Input Voltage
to the Change
in Cathode
Voltage
V
REF
/
V
KA
I
KA
=10mA
V
KA
=10V-
V
REF
-
-1.0
-2.7
-
-1.0
-2.7
-
-1.0
-2.7
mV/V
V
KA
=36V-
10V
-
-0.5
-2.0
-
-0.5
-2.0
-
-0.5
-2.0
Reference
Input Current
I
REF
I
KA
=10mA,
R
1
=10k
,R
2
=
-
1.5
4
-
1.5
4
-
1.5
4
µ
A
Deviation of
Reference
Input Current
Over Full
Temperature
Range
I
REF
/
T
I
KA
=10mA,
R
1
=10k
,R
2
=
T
A
=Full Range
-
0.4
1.2
-
0.4
1.2
-
0.4
1.2
µ
A
Minimum
Cathode Cur-
rent for
Regulation
I
KA(MIN)
V
KA
=V
REF
-
0.45
1.0
-
0.45
1.0
-
0.45
1.0
mA
Off - Stage
Cathode
Current
I
KA(OFF)
V
KA
=36V,
V
REF
=0
-
0.05
1.0
-
0.05
1.0
-
0.05
1.0
µ
A
Dynamic
Impedance
Z
KA
V
KA
=V
REF
,
I
KA
=1 to 100mA
f
1.0kHz
-
0.15
0.5
-
0.15
0.5
-
0.15
0.5
LM431A/LM431B/LM431C
4
Test Circuits
Figure 1. Test Circuit for V
KA
=V
REF
Figure 2. Test Circuit for V
KA
V
REF
LM431A/B/C
LM431A/B/C
LM431A/B/C
Figure 3. Test Circuit for l
KA(OFF)
LM431A/LM431B/LM431C
5
Typical Performance Characteristics
Figure 4.
Cathode Current vs. Cathode 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
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