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AS431
Precision Adjustable Shunt Reference
SEMICONDUCTOR
Features
Temperature-compensated: 30 ppm/C
Trimmed bandgap reference
Internal amplifier with 150 mA capability
Multiple temperature ranges
Low frequency dynamic output
impedance: < 150 m
Low output noise
Robust ESD protection
Description
The AS431 is a three-terminal adjustable shunt regulator providing a
highly accurate bandgap reference. The adjustable shunt regulator is
ideal for a wide variety of linear applications that can be implemented
using external components to obtain adjustable currents and voltages.
In the standard shunt configuration, the combination of low temperature
coefficient (TC), sharp turn-on characteristics, low output impedance
and programmable output voltage make this precision reference a per-
fect zener diode replacement.
The AS431 precision adjustable shunt reference is offered in four
bandgap tolerances: 0.25%, 0.5%, 1.0%, and 2.0%.
CATHODE
TO-92 (LP)
8L SOIC (8D)
ANODE
REFERENCE
CATHODE
REFERENCE
ANODE
ANODE
N/C
CATHODE
ANODE
ANODE
N/C
SOT-89 (S)
5L SOT-23 (5VS)
ANODE
REFERENCE
1
2
3
4
8
7
6
5
ANODE
REFERENCE
N/C
N/C
CATHODE
Circuit Type:
Precision Adjustable
Shunt Regulator
Bandgap Tolerance:
A
C
D
E
Temperature Range:
A = 0
C to 70
C
B = 0
C to 105
C
C = 40
C to +85
C
=
0.25%
=
0.5%
=
1.0%
=
2.0%
Packaging Option:
A
B
T
M
N
Package Style:
8D
5VS
LP
S
= Ammo Pack
= Bulk
= Tube
= Tape and Reel (7" Reel Dia. SOT-23 Only)
= Tape and Reel (13" Reel Dia.)
= 8 Pin, Plastic SOIC
= 5 Pin, SOT-23
= TO-92
= SOT-89
AS431 - A B 8D N
Pin Configuration
Top View
Ordering Information
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AS431
Precision Adjustable Shunt Reference
+
REFERENCE
(R)
ANODE (A)
CATHODE (K)
2.5 V
Recommended Conditions
Parameter
Symbol
Rating
Unit
Cathode Voltage
V
KA
V
REF
to 20
V
Cathode Current
I
K
10
mA
Typical Thermal Resistances
Package
JA
JC
Typical Derating
TO-92
160C/W
80C/W
6.3 mW/C
SOIC
175C/W
45C/W
5.7 mW/C
SOT-89
110C/W
8C/W
9.1 mW/C
SOT-23/5L
575C/W
150C/W
1.7 mW/C
Absolute Maximum Ratings
Parameter
Symbol
Rating
Units
Cathode-Anode Reverse Breakdown
V
KA
37
V
Anode-Cathode Forward Current
I
AK
1
A
Operating Cathode Current
I
KA
250
mA
Reference Input Current
I
REF
10
mA
Continuous Power at 25C
P
D
TO-92
775
mW
8L SOIC
750
mW
SOT-89
1000
mW
5L SOT-23
200
mW
Junction Temperature
T
J
150
C
Storage Temperature
T
STG
65 to 150
C
Lead Temperature, Soldering 10 Seconds
T
L
300
C
Stresses greater than those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent damage to the device. This is a
stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational sec-
tions of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability.
Functional Block Diagram
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AS431
Precision Adjustable Shunt Reference
Figure 1a. Test Circuit 1
Figure 1b. Test Circuit 2
Figure 1c. Test Circuit 3
0
10
20
0.5
5000
0
0
0
15
0.07 mV/
C
0.003%/
C
27 ppm/
C
30
45
60
75
90
105
ppm
mV
%
V
REF
T
Temperature (
C)
TC in mV/
C =
TC in %/
C =
T
A
T
A
X 100
V
REF
(mV)
V
REF
at 25
C
V
REF
TC in ppm/
C =
T
A
X 10
6
V
REF
at 25
C
V
REF
R
1
R
2
I
K
V
IN
V
KA
(V
REF
)
I
REF
I
REF
I
K
V
IN
V
KA
=
V
REF
I
K (OFF)
V
IN
V
KA
Average Temperature Coefficient
Test Circuits
5
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AS431
Precision Adjustable Shunt Reference
I
K
Cathode Current (
A)
900
700
600
500
400
300
200
100
0
100
200
800
1.0
0
1.0
V
KA
Cathode Voltage (V)
2.0
3.0
Low Current Operating Characteristics
V
KA
= V
REF
Temperature Range: 55 to 125
C
125
C
25
C
55
C
I
K
Cathode Current (mA)
150
125
100
75
50
25
0
25
50
75
100
2
1
0
1
2
3
V
KA
Cathode Voltage (V)
High Current Operating Characteristics
V
KA
= V
REF
Temperature Range: 55 to 125
C
I
Z
off Off State Cathode Current (nA)
100
10
1
0.1
0.01
60
30
0
30
T
A
Ambient Temperature (
C)
60
90
120
Off State Leakage
V
KA
= 36 V
V
REF
= 0 V
V
REF
Reference V
oltage (V)
2.56
2.55
2.54
2.53
2.52
2.51
2.50
2.49
2.48
60
30
0
30
T
A
Ambient Temperature (
C)
60
90
120
V
KA
= V
REF
I
K
= 10 mA
Temperature Coefficient as a Function of Trim Value
V
REF
= 2.503 V at 25
C
Figure 4
Figure 5
Figure 2
Figure 3
Typical Performance Curves
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AS431
Precision Adjustable Shunt Reference
3.0
2.5
2.0
1.5
1.0
0.5
0
60
30
0
30
60
90
120
I
REF
Reference Input Current (
A)
T
A
Ambient Temperature (
C)
Reference Input Current
R1 = 10 k
R2 =
I
K
=10 mA
0
10
20
30
40
50
0
3
6
9
V
KA
Cathode Voltage (V)
12
15
18
21
24
27
30
V
REF
Change in Reference V
oltage (mV)
I
K
= 10 mA
Temperature Range: 55 to 125
C
Reference Voltage Line Regulation
125
C
55
C
75
C
25
C
0
C
70
60
50
40
30
20
10
0
10
100
1 k
f Frequency (Hz)
10 k
100 k
Noise V
oltage nV/
H
Z
V
KA
= V
REF
I
K
= 10 mA
T
A
= 25
C
Noise Voltage
Z
KA
Dynamic Impedance (
)
0.150
0.125
0.100
0.075
0.050
0.025
0.0
60
30
0
30
T
A
Free Air Temperature
60
90
120
V
KA
= V
REF
I
KA
= 1 to 100 mA
f
1 kHz
Low Frequency Dynamic Output Impedance
Typical Performance Curves
Figure 6
Figure 7
Figure 8
Figure 9
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