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AS2431
Precision Adjustable Shunt Reference
SEMICONDUCTOR
Features
Temperature-compensated: 15 ppm/C
Trimmed bandgap reference
Internal amplifier with 100 mA capability
Multiple temperature ranges
Low frequency dynamic output
impedance: < 450 m
Low output noise
Description
The AS2431 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 an
excellent error amplifier.
The AS2431 is a direct replacement for the AS431 in low voltage, low
current applications. It is also available in the very small footprint SOT-
23.
CATHODE
TO-92 (LP)
8L SOIC (8D)
ANODE
REFERENCE
CATHODE
REFERENCE
ANODE
ANODE
N/C
CATHODE
ANODE
ANODE
N/C
SOT-89 (S)
3L SOT-23 (3VS)
ANODE
REFERENCE
1
2
3
4
8
7
6
5
CATHODE
REFERENCE
ANODE
Circuit Type:
Precision Adjustable
Shunt Regulator
Bandgap Tolerance:
A =
0.25%
C =
0.5%
D =
1.0%
E =
2.0%
Temperature Range:
AS2431 A C 8D N
Packaging Option:
A
B
T
M
N
Package Style:
= Ammo Pack
= Bulk
= Tube
= Tape and Reel (7" Reel Dia. SOT-23 Only)
= Tape and Reel (13" Reel Dia)
=
=
=
=
=
=
=
=
8 Pin, Plastic SOIC
TO-92
SOT-89
3 Pin, SOT-23
8D
LP
S
3VS
A
B
C
F
0
C to 70
C
0
C to 105
C
40
C to +85
C
55
C to +125
C
Ordering Information
Pin Configuration
Top View
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AS2431
Precision Adjustable Shunt Reference
Absolute Maximum Ratings
Parameter
Symbol
Rating
Units
Cathode-Anode Reverse Breakdown
V
KA
18
V
Anode-Cathode Forward Current
I
AK
1
A
Operating Cathode Current
I
KA
100
mA
Reference Input Current
I
REF
1
mA
Continuous Power Dissipation at 25C
P
D
TO-92
775
mW
8L SOIC
750
mW
SOT-89
1000
mW
3L SOT-23
200
mW
Junction Temperature
T
J
150
C
Storage Temperature
T
STG
65 to 150
C
Lead Temp, 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.
+
REFERENCE
(R)
ANODE (A)
CATHODE (K)
2.5 V
Recommended Conditions
Parameter
Symbol
Rating
Unit
Cathode Voltage
V
KA
V
REF
to 18
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
Functional Block Diagram
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AS2431
Precision Adjustable Shunt Reference
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
Figure 1a. Test Circuit 1
Figure 1b. Test Circuit 2
Figure 1c. Test Circuit 3
Test Circuits
Average Temperature Coefficient
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AS2431
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
= 18 V
V
REF
= 0 V
V
REF
Reference V
oltage (V)
3.53
2.52
2.51
2.50
2.49
2.48
2.47
2.46
2.45
60
30
0
30
TA Ambient Temperature (
C)
60
90
120
V
KA
= V
REF
I
K
= 10 mA
Reference Voltage vs Ambient Temperature
V
REF
= 2.500 V at 25
C
Figure 4
Figure 5
Figure 2
Figure 3
Typical Performance Curves
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AS2431
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
5
10
15
20
25
0
3
6
9
V
KA
Cathode Voltage (V)
12
15
18
V
REF
Change in Reference V
oltage (mV)
I
K
= 10 mA
Temperature Range: 55 to 125
C
30
C
25
C
75
C
125
C
Reference Voltage Line Regulation
70
60
50
40
30
20
10
0
10
100
1 k
f Frequency (Hz)
10 k
100 k
Noise V
oltage nV/
Hz
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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AS2431
Precision Adjustable Shunt Reference
100
10
1.0
Z
KA
Dynamic Impedance (
)
0.1
0.01
1 k
10 k
100 k
f Frequency (Hz)
1 M
10 M
T
A
= 25
C
I
K
= 1 to 100 mA
Dynamic Output Impedance
70
60
50
40
30
20
10
0
1 k
10 k
100 k
1 M
10 M
f Frequency (Hz)
230
I
K
A
V
Small Signal V
oltage Gain (dB)
Temperature Range: 55 to 125
C
I
K
= 10 mA
OUT
GND
15 k
8.25 k
9
F
Small Signal Voltage Gain vs. Frequency
Figure 10
Figure 11
Typical Performance Curves
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AS2431
Precision Adjustable Shunt Reference
6
5
4
3
Input and Output V
otages (V)
2
1
0
1
0
1
2
3
4
5
6
7
t Time (ms)
8
9
10 11 12
Input
Output
Pulse Response
INPUT
MONITOR
220
50
OUT
GND
f
P
= 100 kHz
100
90
80
70
60
50
40
30
20
10
0
10
0
10
1
10
2
10
3
C
L
Load Capacitance (pF)
10
4
10
5
10
6
10
7
150
C
L
10 K
I
K
A
C
D
B
T
A
= 25
C
Stability Boundary Conditions
Stability
Region
I
K
Cathode Current (mA)
A: V
KA
= V
REF
B: V
KA
= 5 V at I
K
= 10 mA
C: V
KA
= 10 V at I
K
= 10 mA
D: V
KA
= 15 V at I
K
= 10 mA
Figure 13
Figure 12
Typical Performance Curves
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