SEMICONDUCTOR
AS431
Precision Adjustable Shunt Reference
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 compo-
nents to obtain adjustable currents and voltages.
In the standard shunt configuration, the combination of low temperature coef-
ficient (TC), sharp turn-on characteristics, low output impedance and pro-
grammable output voltage make this precision reference a perfect zener diode
replacement.
The AS431 precision adjustable shunt reference is offered in four bandgap tol-
erances: ±0.25%, ±0.5%, ±1.0%, and ±2.0%.
Features
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Temperature-compensated: 30 ppm/¡C
Trimmed bandgap reference
Internal amplifier with 150 mA capability
Multiple temperature ranges
Low frequency dynamic output impedance:
< 150 m½
Low output noise
Robust ESD protection
Pin Configuration Ñ
Top view
TO-92 (LP)
CATHODE
CATHODE
ANODE
ANODE
REFERENCE
ANODE
N/C
2
3
4
1
SOIC (D)
8
7
6
5
REFERENCE
ANODE
ANODE
N/C
SOT-89 (S)
SOT-23/5L (DBV)
N/C
N/C
CATHODE
REFERENCE
CATHODE
ANODE
ANODE
REFERENCE
Ordering Information
AS431 A 2 D 7
Circuit Type:
Precision Adjustable
Shunt Regulator
Temperature Range:
A = 0°C to 70°C
B = 0°C to 105°C
C = –40°C to +85°C
Bandgap Tolerance:
2 =
±2%
1 =
±1%
R5 =
±0.5%
R25 =
±0.25%
Packaging Option:
A = Ammo Pack
B = Bulk
T = Tube
7 = Tape and Reel (7" Reel Dia)
13 = Tape and Reel (13" Reel Dia)
Package Style:
D = SOIC
DBV = SOT-23/5L
LP = TO-92
S = SOT-89
ASTEC Semiconductor
1
AS431
Functional Block Diagram
Precision Adjustable Shunt Reference
CATHODE (K)
REFERENCE
(R)
+
Ð
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 at 25¡C
TO-92
8L SOIC
SOT-89
SOT-23/5L
Junction Temperature
Storage Temperature
Lead Temperature, 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
Ð65 to 150
300
mW
mW
mW
mW
¡C
¡C
¡C
Rating
37
1
250
10
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 20
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
ASTEC Semiconductor
2
Precision Adjustable Shunt Reference
Electrical Characteristics
AS431
Electrical Characteristics are guaranteed over full junction temperature range (0 to 105¡C). Ambient temperature must be derated based
on power dissipation and package thermal characteristics. The conditions are: V
KA
= V
REF
and I
K
= 10 mA unless otherwise stated.
Test
Condition
T
A
= 25¡C
Over temp.
ÆV
REF
with Temp*
Ratio of Change in
V
REF
to Cathode
Voltage
Reference Input
Current
I
REF
Temp Deviation
Min I
K
for Regulation
Off State Leakage
Dynamic Output
Impedance
TC
ÆV
REF
ÆV
K
I
REF
ÆI
REF
I
K(min)
I
K(off)
Z
KA
V
REF
= 0 V,
V
KA
= 36 V
f ² 1 kHz
I
K
= 1 to 150 mA
Over temp.
V
REF
to 10 V
10 V to 36 V
Ð2.7
Ð2.0
AS431 (0.25%)
Min.
Typ. Max.
2.496
2.475
0.07
Ð1.0
Ð0.4
0.7
0.4
0.4
0.04
0.15
0.3
4
1.2
1
250
0.5
2.503
2.509
2.530
0.20
Ð2.7
Ð2.0
AS431 (0.5%)
Min.
Typ. Max.
2.490
2.469
0.07
Ð1.0
mV/V
Ð0.4
0.7
0.4
0.4
0.04
0.15
0.3
4
1.2
1
250
0.5
µA
µA
mA
nA
½
2
2
1
3
1
2
2.503
2.515
2.536
0.20
Test
Circuit
1
1
1
Parameter
Reference Voltage
Symbol
V
REF
Unit
V
V
mV/¡C
Parameter
Reference Voltage
Symbol
V
REF
TC
ÆV
REF
ÆV
K
I
REF
ÆI
REF
I
K(min)
I
K(off)
Z
KA
Test
Condition
T
A
= 25¡C
Over temp.
AS431 (1.0%)
Min.
Typ. Max.
2.470
2.449
0.07
2.495
2.520
2.541
0.20
AS431 (2.0%)
Min.
Typ. Max.
2.440
2.430
0.07
Ð2.7
Ð1.0
2.490
2.550
2.569
0.20
Unit
V
V
mV/¡C
mV/V
Test
Circuit
1
1
1
2
2
2
1
3
1
ÆV
REF
with Temp*
Ratio of Change in
V
REF
to Cathode
Voltage
Reference Input
Current
I
REF
Temp Deviation
Min I
K
for Regulation
Off State Leakage
Dynamic Output
Impedance
V
REF
to 10 V
10 V to 36 V
Ð2.7
Ð2.0
Ð1.0
Ð0.4
0.7
0.3
4
1.2
1
250
0.5
Ð2.0
Ð0.4
0.7
0.4
0.4
0.04
0.15
0.3
4
1.2
1
250
0.5
µA
µA
mA
nA
½
Over temp.
0.4
0.4
V
REF
= 0 V,
V
KA
= 36 V
f ² 1 kHz
I
K
= 1 to 150 mA
0.04
0.15
*Calculating Average Temperature Coefficient (TC). Refer to following page.
ASTEC Semiconductor
3
AS431
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
ASTEC Semiconductor
4
Precision Adjustable Shunt Reference
Typical Performance Curves
AS431
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
–55°C
125°C
25°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
= 36 V
V
REF
= 0 V
I
Z
off – Off State Cathode Current (nA)
V
REF
– Reference Voltage (V)
10
2.56
2.55
2.54
2.53
2.52
2.51
2.50
Temperature Coefficient as a Function of Trim Value
V
KA
= V
REF
I
K
= 10 mA
1
0.1
V
REF
= 2.503 V at 25°C
2.49
0.01
–60
2.48
–60
–30
0
30
60
90
120
–30
0
30
60
90
120
T
A
– Ambient Temperature (°C)
T
A
– Ambient Temperature (°C)
Figure 4
Figure 5
ASTEC Semiconductor
5
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