SEMICONDUCTOR
AS2431
Reference
Precision Adjustable Shunt
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.
Features
•
•
•
•
•
•
Temperature-compensated: 15 ppm/°C
Trimmed bandgap reference
Internal amplifier with 100 mA capability
Multiple temperature ranges
Low frequency dynamic output
impedance: < 450 mΩ
Low output noise
Pin Configuration –
Top View
TO-92 (LP)
CATHODE
CATHODE
ANODE
ANODE
REFERENCE
ANODE
N/C
2
3
4
1
8L SOIC (8D)
8
7
6
5
REFERENCE
ANODE
ANODE
N/C
SOT-89 (S)
3L SOT-23 (3VS)
CATHODE
CATHODE
ANODE
REFERENCE
ANODE
REFERENCE
Ordering Information
AS2431 A C 8D N
Circuit Type:
Precision Adjustable
Shunt Regulator
Bandgap Tolerance:
A =
±0.25%
C =
±0.5%
D =
±1.0%
E =
±2.0%
Temperature Range:
A = 0°C to 70°C
B = 0°C to 105°C
C = –40°C to +85°C
F = –55°C to +125°C
Packaging Option:
A = Ammo Pack
B = Bulk
T = Tube
M = Tape and Reel (7" Reel Dia. SOT-23 Only)
N = Tape and Reel (13" Reel Dia)
Package Style:
8D = 8 Pin, Plastic SOIC
LP = TO-92
S = SOT-89
3VS = 3 Pin, SOT-23
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AS2431
Functional Block Diagram
Precision Adjustable Shunt Reference
CATHODE (K)
REFERENCE
(R)
+
–
2.5 V
ANODE (A)
Absolute Maximum Ratings
Parameter
Cathode-Anode Reverse Breakdown
Anode-Cathode Forward Current
Operating Cathode Current
Reference Input Current
Continuous Power Dissipation at 25°C
TO-92
8L SOIC
SOT-89
3L SOT-23
Junction Temperature
Storage Temperature
Lead Temp, Soldering 10 Seconds
T
J
T
STG
T
L
Symbol
V
KA
I
AK
I
KA
I
REF
P
D
775
750
1000
200
150
–65 to 150
300
mW
mW
mW
mW
°C
°C
°C
Rating
18
1
100
1
Units
V
A
mA
mA
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.
Recommended Conditions
Parameter
Cathode Voltage
Cathode Current
Symbol
V
KA
I
K
Rating
V
REF
to 18
10
Unit
V
mA
Typical Thermal Resistances
Package
TO-92
SOIC
SOT-89
θ
JA
160°C/W
175°C/W
110°C/W
θ
JC
80°C/W
45°C/W
8°C/W
150°C/W
Typical Derating
6.3 mW/°C
5.7 mW/°C
9.1 mW/°C
1.7 mW/°C
SOT-23/5L 575°C/W
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18
AS2431
Average Temperature Coefficient
ppm
mV
Precision Adjustable Shunt Reference
0
0
0
∆V
REF
∆T
–10
• TC in mV/°C =
∆V
REF
(mV)
∆T
A
∆V
REF
%
5000
0.5
• TC in %/°C =
V
REF
at 25°C
∆T
A
∆V
REF
X 100
–20
0
15
30
45 60 75
Temperature (°C)
90
105
• TC in ppm/°C =
V
REF
at 25°C
∆T
A
X 10
6
0.07 mV/°C
0.003%/°C
27 ppm/°C
Test Circuits
V
IN
V
KA
= V
REF
V
IN
V
KA
V
IN
V
KA
I
REF
I
K
I
K
R
1
I
REF
(V
REF
)
R
2
I
K (OFF)
Figure 1a. Test Circuit 1
Figure 1b. Test Circuit 2
Figure 1c. Test Circuit 3
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Precision Adjustable Shunt Reference
Typical Performance Curves
AS2431
Low Current Operating Characteristics
900
800
700
I
K
– Cathode Current (mA)
600
I
K
– Cathode Current (µA)
500
400
300
200
100
0
–100
–200
–1.0
0
1.0
2.0
3.0
125°C
25°C
–55°C
V
KA
= V
REF
Temperature Range: –55 to 125°C
150
125
100
75
50
25
0
–25
–50
–75
–100
–2
High Current Operating Characteristics
V
KA
= V
REF
Temperature Range: –55 to 125°C
–1
0
1
2
3
V
KA
– Cathode Voltage (V)
V
KA
– Cathode Voltage (V)
Figure 2
Figure 3
Off State Leakage
100
V
KA
= 18 V
V
REF
= 0 V
I
Z
off – Off State Cathode Current (nA)
V
REF
– Reference Voltage (V)
10
3.53
2.52
2.51
2.50
Reference Voltage vs Ambient Temperature
V
KA
= V
REF
I
K
= 10 mA
V
REF
= 2.500 V at 25°C
2.49
2.48
2.47
2.46
1
0.1
0.01
–60
–30
0
30
60
90
120
2.45
–60
–30
0
30
60
90
120
T
A
– Ambient Temperature (°C)
TA – Ambient Temperature (°C)
Figure 4
Figure 5
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AS2431
Typical Performance Curves
Precision Adjustable Shunt Reference
Reference Input Current
3.0
R1 = 10 kΩ
R2 =
∞
I
K
=10 mA
0
Reference Voltage Line Regulation
–30°C
∆
V
REF
– Change in Reference Voltage (mV)
–5
2.5
I
REF
– Reference Input Current (µA)
2.0
–10
25°C
–15
75°C
–20
I
K
= 10 mA
Temperature Range: –55 to 125°C
–25
0
3
6
9
12
15
125°C
1.5
1.0
0.5
0
–60
–30
0
30
60
90
120
18
T
A
– Ambient Temperature (°C)
V
KA
– Cathode Voltage (V)
Figure 6
Figure 7
Noise Voltage
70
60
V
KA
= V
REF
I
K
= 10 mA
T
A
= 25°C
Z
KA
– Dynamic Impedance (Ω)
0.150
Low Frequency Dynamic Output Impedance
V
KA
= V
REF
I
KA
= 1 to 100 mA
f
≤
1 kHz
0.125
50
Noise Voltage nV/√Hz
0.100
40
30
0.075
20
0.050
10
0
10
100
1k
f – Frequency (Hz)
10 k
100 k
0.025
0.0
–60
–30
0
30
60
90
120
T
A
– Free Air Temperature
Figure 8
Figure 9
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