SEMICONDUCTOR
1.24V Precision Adjustable Shunt Reference
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.
AS432
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
Top view
Pin Configuration —
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
5L SOT-23 (5VS)
N/C
N/C
CATHODE
REFERENCE
ANODE
SOT-89 (S)
CATHODE
ANODE
REFERENCE
ANODE
3L SOT-23 (3VS)
CATHODE
REFERENCE
Ordering Information
AS432 A C 8D N
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 = 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
5VS = 5 Pin, SOT-23
3VS = 3 Pin, SOT-23
= SOT-89
S
LP = TO-92
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AS432
Functional Block Diagram
1.24V Precision Adjustable Shunt Reference
CATHODE (K)
REFERENCE
(R)
+
–
+
–
1.24 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-23/3L/5L
Junction Temperature
Storage Temperature
Lead Temperature (Soldering 10 sec.)
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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AS432
Typical Performance Curves
1.24V Precision Adjustable Shunt Reference
* Calculating Average Temperature Coefficient (TC)
ppm
mV
∆V
REF
(mV)
∆T
A
∆V
REF
2000
0.2
–5
• TC in %/°C =
V
REF
at 25°C
∆T
A
∆V
REF
–10
0
15
30
45 60 75
Temperature (°C)
90
105
• TC in ppm/°C =
V
REF
at 25°C
∆T
A
%
0
0
∆T
∆V
REF
0
• TC in mV/°C =
X 100
X 10
6
0.021 mV/°C
0.008%/°C
8.0 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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1.24V Precision Adjustable Shunt Reference
Typical Performance Curves
AS432
Low Current Operating Characteristics
900
800
700
I
K
– Cathode Current (mA)
I
K
– Cathode Current (µA)
600
500
400
300
200
100
0
–55°C
–100
–200
–0.5
0
0.5
V
KA
– Cathode Voltage (V)
1.0
25°C
1.5
–75
–100
–2
125°C
175
150
125
100
75
50
25
0
–25
–50
High Current Operating Characteristics
V
KA
= V
REF
Temperature Range –55 to 125°C
–1
0
V
KA
– Cathode Voltage (V)
1
2
Figure 2
Figure 3
Off State Leakage
100
V
KA
= 15 V
V
REF
= 0 V
I
Z
off – Off State Cathode Current (nA)
V
REF
– Reference Voltage (V)
10
1.27
1.26
1.25
1.24
Reference Voltage vs Ambient Temperature
V
KA
= V
REF
I
K
= 10 mA
V
REF
= 1.240 V at 25°C
1.23
1.22
1.21
1.20
1
0.1
0.01
–60
–30
0
30
60
90
120
1.19
–60
–30
0
30
60
90
120
T
A
– Ambient Temperature (°C)
T
A
– Ambient Temperature (°C)
Figure 4
Figure 5
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AS432
Typical Performance Curves
1.24V Precision Adjustable Shunt Reference
Reference Input Current
2.4
R1 = 10 kΩ
R2 =
∞
I
K
= 10 mA
2.3
0
Reference Voltage Line Regulation
∆V
REF
– Change in Reference Voltage (mV)
I
REF
– Reference Input Current (µA)
–10
–40°C
–20
25°C
–30
75°C
2.2
2.1
–40
I
K
= 10 mA
Temperature Range: –55 to 125°C
125°C
2.0
–60
–50
–30
0
30
60
90
120
T
A
– Ambient Temperature (°C)
0
3
6
9
12
15
18
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 (mΩ)
30
40
Low Frequency Dynamic Output Impedance
V
KA
= V
REF
V
KA
= 1 to 100 mA
f
≤
1kHz
50
Noise Voltage nV/√Hz
40
30
20
10
0
10
20
10
100
1k
f – Frequency (Hz)
10 k
100 k
0
–60
–30
0
30
60
90
120
T
A
– Free Air Temperature (°C)
Figure 8
Figure 9
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