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AS432
1.24V Precision Adjustab le Shunt Ref erence
SEMICONDUCTOR
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 mΩ
•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 current, and holds off more than 18V so its use is not limited to
low power, low voltage systems. Significant care has been taken to pro-
vide adequate AC bandwidth to allow the AS432 as an amplifier in con-
trol systems and power electronics.
Pin Configuration — Top view
Ordering Information
CATHODE
TO-92 (LP) 8L SOIC (8D)
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
5L SOT-23 (5VS)
ANODE
REFERENCE
N/C
N/C
CATHODE
3L SOT-23 (3VS)
CATHODE
REFERENCE
ANODE
Circuit Type:
1.24V 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
B
T
M
N
Package Style:
8D
5VS
3VS
S
LP
= 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
= 3 Pin, SOT-23
= SOT-89
= TO-92
AS432 A C 8D N
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AS432 1.24V Precision Adjustable Shunt Reference
Functional Block Diagram
–
+
REFERENCE
(R)
ANODE
(
A
)
CATHODE (K)
1.24 V
–
+
Absolute Maximum Ratings
Parameter Symbol Rating Units
Cathode-Anode Reverse Breakdown VKA 18 V
Anode-Cathode Forward Current IAK 1A
Operating Cathode Current IKA 100 mA
Reference Input Current IREF 1mA
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 –65 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-23/5L 575°C/W 150°C/W 1.7 mW/°C
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AS432 1.24V Precision Adjustable Shunt Reference
R1
R2
IK
VIN VKA
(VREF)IREF
IREF IK
VIN VKA = VREF
IK (OFF)
VIN VKA
0
–5
–10
0.22000
00
015
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
Figure 1a. Test Circuit 1 Figure 1b. Test Circuit 2 Figure 1c. Test Circuit 3
Test Circuits
Typical Performance Curves
* Calculating Average Temperature Coefficient (TC)
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AS4321.24V Precision Adjustable Shunt Reference
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
Figure 4 Figure 5
Figure 2 Figure 3
Typical Performance Curves
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AS432 1.24V Precision Adjustable Shunt Reference
–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
03691215 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
Typical Performance Curves
Figure 6 Figure 7
Figure 8 Figure 9
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AS4321.24V Precision Adjustable Shunt Reference
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
Figure 10
Figure 11
Typical Performance Curves
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AS432 1.24V Precision Adjustable Shunt Reference
4
3
Input and Output Votages (V)
2
1
0
–1 01234567
t – Time (µs) 891011 12
Input
Output
Pulse Response
INPUT
MONITOR 220 Ω
50 Ω
OUT
GND
fP = 100 kHz
Figure 12
Typical Performance Curves
