1
ASTEC Semiconductor
AS432
1.24V Precision Adjustable Shunt Reference/Amplifier
Features
¥
Temperature-compensated:
50 ppm/¡C
¥
0.25% to 2.0% bandgap offered
¥
Internal amplifier with 150 mA
capability
¥
Multiple temperature ranges
¥
Low frequency dynamic output
impedance: < 150 m½
¥
Low output noise
Description
The AS432 is a three terminal adjustable shunt regulator utilizing an accurate
1.24V bandgap reference. The AS432 is functionally similar to an AS431 except
for its lower reference voltage, making it usable in a wide variety of low voltage
applications.
Because of its robust bipolar technology, the AS432 handles a wide range of cur-
rent, and holds off more than 18V so its use is not limited to low power, low volt-
age systems. Significant care has been taken to provide adequate AC bandwidth
to allow the AS432 as an amplifier in control systems and power electronics.
SEMICONDUCTOR
Pin Configuration Ñ Top view
Ordering Information
CATHODE
TO-92 (LP) SOIC (D)
ANODE
REFERENCE
REFERENCE
ANODE
ANODE
N/C
CATHODE
ANODE
ANODE
N/C
SOT-89 (S)
CATHODE
ANODE
REFERENCE
1
2
3
4
8
7
6
5
SOT-23/5L (DBV)
ANODE
REFERENCE
N/C
N/C
CATHODE
SOT-23/3L (VS)
CATHODE
REFERENCE
ANODE
Circuit Type:
1.24V Precision Adjustable
Shunt Regulator/Amplifier
Temperature Range:
A
B
C
Bandgap Tolerance:
2
1
R5
R25
= 0°C to 70°C
= 0°C to 105°C
= –40°C to +85°C
= ±2%
= ±1%
= ±0.5%
= ±0.25%
Packaging Option:
A
B
T
7
13
Package Style:
D
DBV
LP
S
VS
= Ammo Pack
= Bulk
= Tube
= Tape and Reel (7" Reel Dia)
= Tape and Reel (13" Reel Dia)
= SOIC
= SOT-23/5L
= TO-92
= SOT-89
= SOT-23/3L
AS432 A 2 D 7
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ASTEC Semiconductor
AS432 1.24V Precision Adjustable Shunt Reference/Amplifier
Functional Block Diagram
Ð
+
REFERENCE
(R)
ANODE (A)
CATHODE (K)
1.24 V
Ð
+
Absolute Maximum Ratings
Parameter Symbol Rating Units
Cathode-Anode Reverse Breakdown VKA 18 V
Anode-Cathode Forward Current IAK 1 A
Operating Cathode Current IKA 100 mA
Reference Input Current IREF 1 mA
Continuous Power at 25¡C PD
TO-92 775 mW
8L SOIC 750 mW
SOT-89 1000 mW
SOT-23/3L/5L 200 mW
Junction Temperature TJ150 ¡C
Storage Temperature TSTG Ð65 to 150 ¡C
Lead Temperature (Soldering 10 sec.) TL300 ¡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.
Recommended Conditions
Parameter Symbol Rating Unit
Cathode Voltage VKA VREF to 18 V
Cathode Current IK10 mA
Typical Thermal Resistances
Package θJA θJC Typical Derating
TO-92 160¡C/W 80¡C/W 6.3 mW/¡C
SOIC 175¡C/W 45¡C/W 5.7 mW/¡C
SOT-89 110¡C/W 8¡C/W 9.1 mW/¡C
SOT-23/3L/5L 575¡C/W 150¡C/W 1.7 mW/¡C
3
ASTEC Semiconductor
AS4321.24V Precision Adjustable Shunt Reference/Amplifier
Electrical Characteristics
Electrical characteristics are guaranteed over the full junction temperature range (0Ð105¡C). Ambient temperature must be derated
based upon power dissipation and package thermal characteristics. Unless otherwise stated, test conditions are: VKA = VREF and
IK= 10 mA.
Test AS432 (0.25%) AS432 (0.5%)
Parameter Symbol Condition Min. Typ. Max. Min. Typ. Max. Unit
Output Voltage VREF IK= 10 mA 1.237 1.240 1.243 1.234 1.240 1.246 V
TJ= 25¡C
VK= VREF
Line Regulation ÆVREF VKA = 1.25 to 15 V 28 50 28 50 mV
Load Regulation ÆVREF IK= 1 to 100 mA 3.9 6 3.9 6 mV
Temperature Deviation ÆVREF 0 < TJ< 105¡C 5 10 5 10 mV
Reference Input Current IREF 2.3 6 2.3 6 µA
Reference Input Current ÆIREF 0 < TJ< 105¡C 0.14 0.6 0.14 0.6 µA
Temperature Coefficient
Minimum Cathode IK(min) 0.2 1 0.2 1 mA
Current for Regulation
Off State Leakage IK(min) VREF = 0 V, 0.04 500 0.04 500 nA
VKA = 15 V
Test AS432 (1.0%) AS432 (2.0%)
Parameter Symbol Condition Min. Typ. Max. Min. Typ. Max. Unit
Output Voltage VREF IK= 10 mA 1.228 1.240 1.252 1.215 1.240 1.256 V
TJ= 25¡C
VK= VREF
Line Regulation ÆVREF VKA = 1.25 to 15 V 28 50 28 50 mV
Load Regulation ÆVREF IK= 1 to 100 mA 3.9 6 3.9 6 mV
Temperature Deviation ÆVREF 0 < TJ< 105¡C 5 12 5 12 mV
Reference Input Current IREF 2.3 6 2.3 6 µA
Reference Input Current ÆIREF 0 < TJ< 105¡C 0.14 0.6 0.14 0.6 µA
Temperature Coefficient
Minimum Cathode IK(min) 0.2 1 0.2 1 mA
Current for Regulation
Off State Leakage IK(min) VREF = 0 V, 0.04 500 0.04 500 nA
VKA = 15 V
*Temperature deviation is defined as the maximum deviation of the reference over the given temperature range and does not imply
an incremental deviation at any given temperature.
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ASTEC Semiconductor
AS432 1.24V Precision Adjustable Shunt Reference/Amplifier
Test Circuits
Figure 1a. Test Circuit 1 Figure 1b. Test Circuit 2 Figure 1c. Test Circuit 3
R1
R2
IK
VIN VKA
(VREF)IREF
IREF IK
VIN VKA = VREF
IK (OFF)
VIN VKA
Typical Performance Curves
*Calculating Average Temperature Coefficient (TC)
0
–5
–10
0.22000
0 0
0 15
0.021 mV/°C
0.008%/°C
8.0 ppm/°C
30 45 60 75 90 105
ppm
mV
%
∆VREF
∆T
Temperature (°C)
• TC in mV/°C =
• TC in %/°C =
∆TA
∆TA
X 100
∆VREF (mV)
VREF at 25°C
∆VREF
• TC in ppm/°C = ∆TA
X 106
VREF at 25°C
∆VREF
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ASTEC Semiconductor
AS4321.24V Precision Adjustable Shunt Reference/Amplifier
Typical Performance
Figure 2
Figure 4
Figure 3
Figure 5
VKA – Cathode Voltage (V)
IK – Cathode Current (µA)
–0.5 0 0.5 1.0 1.5
–200
–100
0
100
200
300
400
500
600
700
800
900 Low Current Operating Characteristics
–55°C
25°C
125°C
IK – Cathode Current (mA)
VKA – Cathode Voltage (V)
–2 –1 0 1 2
–100
–75
–50
–25
0
25
50
75
100
125
150
175 High Current Operating Characteristics
VKA = VREF
Temperature Range –55 to 125°C
–60 –30 0 30
TA – Ambient Temperature (°C)
60 90 120
IZ off – Off State Cathode Current (nA)
100
10
1
0.1
0.01
Off State Leakage
VKA = 15 V
VREF = 0 V
–60 –30 0 30
TA – Ambient Temperature (°C)
60 90 120
VREF – Reference Voltage (V)
1.27
1.26
1.25
1.24
1.23
1.22
1.21
1.20
1.19
Reference Voltage vs Ambient Temperature
VKA = VREF
IK = 10 mA
VREF = 1.240 V at 25°C
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ASTEC Semiconductor
AS432 1.24V Precision Adjustable Shunt Reference/Amplifier
Typical Performance Curves
Figure 6
Figure 8
Figure 7
Figure 9
–60 –30 0 30
TA – Ambient Temperature (°C)
60 90 120
IREF – Reference Input Current (µA)
2.4
2.3
2.2
2.1
2.0
Reference Input Current
R1 = 10 kΩ
R2 = ∞
IK = 10 mA
0 3 6 9 12 15 18
–40°C
25°C
75°C
125°C
VKA – Cathode Voltage (V)
∆VREF – Change in Reference Voltage (mV)
0
–10
–20
–30
–40
–50
Reference Voltage Line Regulation
IK = 10 mA
Temperature Range: –55 to 125°C
10 100 1 k 10 k 100 k
f – Frequency (Hz)
70
60
50
40
30
20
10
0
Noise Voltage nV/√Hz
Noise Voltage
VKA = VREF
IK = 10 mA
TA = 25°C
–60 –30 0 30
TA – Free Air Temperature (°C)
60 90 120
40
30
20
10
0
ZKA – Dynamic Impedance (mΩ)
Low Frequency Dynamic Output Impedance
VKA = VREF
VKA = 1 to 100 mA
f ≤ 1kHz
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ASTEC Semiconductor
AS4321.24V Precision Adjustable Shunt Reference/Amplifier
Typical Performance Curves
Figure 10
Figure 11
100
10
1.0
ZKA – Dynamic Impedance (Ω)
0.1
0.01
1 k 10 k 100 k
f – Frequency (Hz) 1 M 10 M
TA = 25°C
IK = 1 to 100 mA
Dynamic Output Impedance
80
70
60
50
40
30
20
10
01 k 10 k 100 k 1 M 10 M
f – Frequency (Hz)
230 Ω
IK
AV – Small Signal Voltage Gain (dB)
Temperature Range: –55° to 125°C
IK = 10 mA
OUT
GND
15 k
8.25 k
9 µF
Small Signal Voltage Gain vs. Frequency
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ASTEC Semiconductor
AS432 1.24V Precision Adjustable Shunt Reference/Amplifier
Typical Performance Curves
Figure 12
Figure 13
4
3
Input and Output Votages (V)
2
1
0
–1 0 1 2 3 4 5 6 7
t – Time (µs) 8 9 10 11 12
Input
Output
Pulse Response
INPUT
MONITOR 220 Ω
50 Ω
OUT
GND
fP = 100 kHz
100
90
80
70
60
50
40
30
20
10
0
100101102103
CL – Load Capacitance (pF)
104105106107
150 Ω
CL
10 K
IK
A
C
D
B
TA = 25°C
Stability Boundary Conditions
Stability
Region
IK – Cathode Current (mA)
A: VKA = VREF
B: VKA = 5 V at IK = 10 mA
C: VKA = 10 V at IK = 10 mA
D: VKA = 15 V at IK = 10 mA
