Data Sheet
1
BCD Semiconductor Manufacturing Limited
ADJUSTABLE PRECISION SHUNT REGULATORS AS431
Dec. 2012 Rev. 2. 6
General Description
The AS431 is a three-terminal adjustable shunt regula-
tor with guaranteed thermal stability over a full opera-
tion range. It features sharp turn-on characteristics, low
temperature coefficient and low output impedance,
which make it ideal substitute for Zener diode in appli-
cations such as switching power supply, charger and
other adjustable regulators.
The output voltage of AS431 can be set to any value
between VREF (2.5V) and the corresponding maximum
cathode voltage (36V).
The AS431 precision reference is offered in two volt-
age tolerance: 0.5% and 1.0%.
This IC is available in 4 packages: TO-92 (bulk or
ammo packing), SOT-23, SOT-23-5 and SOT-89.
Features
·Programmable Precise Output Voltage from 2.5V
to 36V
·High Stability under Capacitive Load
·Low Temperature Deviation: 4.5mV Typical
·Low Equivalent Full-range Temperature Coeffi-
cient with 20PPM/oC Typical
·Sink Current Capacity from 1mA to 100mA
·Low Output Noise
·Wide Operating Range of -40 to 125oC
Applications
·Charger
·Voltage Adapter
·Switching Power Supply
·Graphic Card
·Precision Voltage Reference
Figure 1. Package Types of AS431
SOT-23
SOT-89
SOT-23-5
TO-92(Bulk Packing) TO-92(Ammo Packing)
Data Sheet
2
BCD Semiconductor Manufacturing Limited
ADJUSTABLE PRECISION SHUNT REGULATORS AS431
Dec. 2012 Rev. 2. 6
Figure 2. Pin Configuration of AS431 (Top View)
Figure 3. Functional Block Diagram of AS431
Functional Block Diagram
REF
VREF
CATHODE
ANODE
+
-
Pin Configuration
Z Package
(SOT-23)
N Package R Package
(SOT-89)
ANODE
REF REF ANODE
K Package
(SOT-23-5)
NC ANODE
REF
CATHODE
ANODE
REF
1
2
3
CATHODE
CATHODE
Z Package
CATHODE
ANODE
REF
1
2
3
(TO-92(Bulk Packing)) (TO-92(Ammo Packing))
3
21
123
1
2
34
5
Note 1: Pin 2 is attached to substrate and
must be connected to ANODE or open
*
*
(Note 1)
CATHODE
Data Sheet
3
BCD Semiconductor Manufacturing Limited
ADJUSTABLE PRECISION SHUNT REGULATORS AS431
Dec. 2012 Rev. 2. 6
Ordering Information
Circuit Type
Voltage Tolerance
B: 1.0%
A: 0.5%
E1: Lead Free
AS431   -
Package
TR: Tape and Reel or Ammo
Blank: Bulk
N: SOT-23 K: SOT-23-5
R: SOT-89 Z: TO-92
Package Temperature
Range
Voltage
Tolerance
Part Number Marking ID Packing
Type
Lead Free Green Lead Free Green
SOT-23 -40 to 125oC
0.5% AS431ANTR-E1 AS431ANTR-G1 EB5 GB5 Tape & Reel
1.0% AS431BNTR-E1 AS431BNTR-G1 EB6 GB6 Tape & Reel
SOT-23-5 -40 to 125oC
0.5% AS431AKTR-E1 AS431AKTR-G1 E6H G6H Tape & Reel
1.0% AS431BKTR-E1 AS431BKTR-G1 E6I G6I Tape & Reel
TO-92 -40 to 125oC
0.5% AS431AZ-E1 AS431AZ-G1 AS431AZ-E1 AS431AZ-G1 Bulk
0.5% AS431AZTR-E1 AS431AZTR-G1 AS431AZ-E1 AS431AZ-G1 Ammo
1.0% AS431BZ-E1 AS431BZ-G1 AS431BZ-E1 AS431BZ-G1 Bulk
1.0% AS431BZTR-E1 AS431BZTR-G1 AS431BZ-E1 AS431BZ-G1 Ammo
SOT-89 -40 to 125oC
0.5% AS431ARTR-E1 AS431ARTR-G1 E43G G43G Tape & Reel
1.0% AS431BRTR-E1 AS431BRTR-G1 E43H G43H Tape & Reel
G1: Green
BCD Semiconductor's Pb-free products, as designated with "E1" suffix in the part number, are RoHS compliant. Products with
"G1" suffix are available in green packages.
Data Sheet
4
BCD Semiconductor Manufacturing Limited
ADJUSTABLE PRECISION SHUNT REGULATORS AS431
Dec. 2012 Rev. 2. 6
Parameter Symbol Value Unit
Cathode Voltage VKA 40 V
Cathode Current Range (Continuous) IKA -100 to 150 mA
Reference Input Current Range IREF 10 mA
Power Dissipation PD
Z, R Package: 770
mW
N, K Package: 370
Junction Temperature TJ150 oC
Storage Temperature Range TSTG -65 to 150 oC
ESD (Human Body Model) ESD 2000 V
Parameter Symbol Min Max Unit
Cathode Voltage VKA VREF 36 V
Cathode Current IKA 1.0 100 mA
Operating Ambient
Temperature Range TA-40 125 oC
Recommended Operating Conditions
Note 2: Stresses greater than those listed under "Absolute Maximum Ratings" may cause permanent damage to the
device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond
those indicated under "Recommended Operating Conditions" is not implied. Exposure to "Absolute Maximum
Ratings" for extended periods may affect device reliability.
Absolute Maximum Ratings (Note 2)
Data Sheet
5
Dec. 2012 Rev. 2. 6 BCD Semiconductor Manufacturing Limited
ADJUSTABLE PRECISION SHUNT REGULATORS AS431
Parameter Test
Circuit Symbol Conditions Min Typ Max Unit
Reference Voltage 0.5% 4VREF VKA=VREF, IKA=10mA 2.487 2.500 2.512 V
1.0% 2.475 2.500 2.525
Deviation of Reference Voltage
Over Full Temperature Range 4ΔVREF
VKA=VREF
IKA= 10mA
0 to 70oC4.5 8
mV
-40 to 85oC4.5 10
-40 to 125oC4.5 16
Ratio of Change in Reference
Voltage to the Change in
Cathode Voltage
5ΔVREF
ΔVKA
IKA=10mA
ΔVKA=
10V to VREF
-1.0 -2.7
mV/V
ΔVKA=
36V to 10V -0.5 -2.0
Reference Current 5 IREF IKA=10mA,R1=10KΩ, R2=0.7 4 μA
Deviation of Reference Current
Over Full Temperature Range 5ΔIREF
IKA=10mA, R1=10KΩ
R2=∞, TA=-40 to 125oC0.4 1.2 μA
Minimum Cathode Current for
Regulation 4IKA
(Min) VKA=VREF 0.4 1.0 mA
Off-state Cathode Current 6 IKA
(Off) VKA=36V, VREF=0 0.05 1.0 μA
Dynamic Impedance 4 ZKA
VKA=VREF, IKA=1 to 100mA,
f 1.0KHz 0.15 0.5 Ω
Thermal Resistance θJC
SOT-23 135.9
oC/W
SOT-23-5 135.9
TO-92 81.9
SOT-89 29.8
Electrical Characteristics
Operating Conditions: TA=25oC, unless otherwise specified.
Data Sheet
6
BCD Semiconductor Manufacturing Limited
ADJUSTABLE PRECISION SHUNT REGULATORS AS431
Dec. 2012 Rev. 2. 6
Figure 4. Test Circuit 4 for VKA=VREF
Figure 5. Test Circuit 5 for VKA>VREF
Figure 6. Test Circuit 6 for IOFF
IOFF
VIN VKA
Electrical Characteristics (Continued)
VIN VKA
R1
IKA
VREF
VIN VKA
IKA
R1
R2 VREF
VKA=VREF(1+R1/R2)+ IREF*R1
IREF
R3
Data Sheet
7
Dec. 2012 Rev. 2. 6 BCD Semiconductor Manufacturing Limited
ADJUSTABLE PRECISION SHUNT REGULATORS AS431
Figure 7. Reference Voltage vs. Ambient Temperature Figure 8. Reference Current vs. Ambient Temperature
Figure 9. Cathode Current vs. Cathode Voltage Figure 10. Cathode Current vs. Cathode Voltage
-60 -40 -20 0 20 40 60 80 100 120 140
2.485
2.490
2.495
2.500
2.505
2.510
Reference Voltage (V)
Ambient Temperature (oC)
VKA = VREF
IKA = 10mA
-2-10123
-100
-50
0
50
100
150
Cathode Current (mA)
Cathode Voltage (V)
VKA=VREF
TA=250C
-1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5
-200
0
200
400
600
800
Cathode Current (μA)
Cathode Voltage (V)
VKA=VREF
TA=250C
Typical Performance Characteristics
Data Sheet
8
BCD Semiconductor Manufacturing Limited
ADJUSTABLE PRECISION SHUNT REGULATORS AS431
Dec. 2012 Rev. 2. 6
Typical Performance Characteristics (Continued)
Figure 11. Off-State Cathode Current vs. Figure 12. Ratio of Delta Reference Voltage to the
Ambient Temperature Ratio of Delta Cathode Voltage
-40-20 0 20406080100120
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
Off-State Cathode Current (μA)
Ambient Temperature (oC)
VKA=36V
VREF=0
-40 -20 0 20 40 60 80 100 120
-1.4
-1.3
-1.2
-1.1
-1.0
-0.9 VKA=3.5V to 36V
ΔVREF / ΔVKA (mV/V)
Ambient Temperature (oC)
Figure 13. Small Signal Voltage Gain vs. Frequency
10μF
8.2K
15K I KA
Output
242
GND
1k 10k 100k 1M
-10
0
10
20
30
40
50
60
70
Voltage Gain (dB)
Small Signal Frequency (Hz)
TA=250C
IKA=10mA
Data Sheet
9
Dec. 2012 Rev. 2. 6 BCD Semiconductor Manufacturing Limited
ADJUSTABLE PRECISION SHUNT REGULATORS AS431
Typical Performance Characteristics (Continued)
Figure 14. Reference Impedance vs. Frequency
1K 10K 100K 1,000K
0.1
1
10
Reference Impedance (Ω)
Frequency (Hz)
IKA=10mA
TA=25oC
GND
Output
50
1K
IKA
Figure 15. Stability Boundary Conditions vs. Load Capacitance
IKA
R1 (10K)
R2
150
0
10
20
30
40
50
60
70
80
90
100
10
1
0.1
0.010.001
Stable
Stable
Cathode Current (mA)
Load Capacitance (μF)
TA=25oC
VKA=VREF
VKA= 5V:No oscillation
VKA=10V:No oscillation
VKA=15V:No oscillation
Data Sheet
10
BCD Semiconductor Manufacturing Limited
ADJUSTABLE PRECISION SHUNT REGULATORS AS431
Dec. 2012 Rev. 2. 6
Typical Performance Characteristics (Continued)
Figure 16. Pulse Response of Input and Output Voltage
Pulse
Generator
f=100KHz
220
50
Output
GND
0246
0
1
2
3
4
5
Input
Input and Output Voltage (V)
Time (μS)
Output
Data Sheet
11
Dec. 2012 Rev. 2. 6 BCD Semiconductor Manufacturing Limited
ADJUSTABLE PRECISION SHUNT REGULATORS AS431
VIN VOUT
R1
R2
VREF
AS431
R3
VIN VOUT
R4
R1
R2
VREF
R3
AS431
IOUT
VIN
AS431
R2
R1
Figure 17. Shunt Regulator
Figure 18. High Current Shunt Regulator
VOUT=(1+R1/R2)*VREF
VOUT=(1+R2/R3)*VREF
IOUT=VREF/R2 + IKA
Figure 19. Current Source or Current Limit
Typical Application
Data Sheet
12
BCD Semiconductor Manufacturing Limited
ADJUSTABLE PRECISION SHUNT REGULATORS AS431
Dec. 2012 Rev. 2. 6
Figure 21. PWM Converter with Reference
Figure 20. Precision 5V 1A Regulator
AZ1117
VIN VOUT
Adjust
8.2K
AS431
R1
R2
R3
250
250
5V, 1A
PWM Controller
C1
R1
R2 680
U2
3
4
PS521
C2
2
R3 R4
R5
VOUT
AS431
Q1
COMP
VFB
Typical Application (Continued)
Data Sheet
13
Dec. 2012 Rev. 2. 6 BCD Semiconductor Manufacturing Limited
ADJUSTABLE PRECISION SHUNT REGULATORS AS431
Mechanical Dimensions
TO-92(Bulk Packing) Unit: mm(inch)
2.420(0.095)
2.660(0.105)
0.360(0.014)
0.760(0. 030)
Φ
1.600(0.063)
MAX
12.500(0.492)
15.500(0.610)
1.270(0.050)
TYP
3.300(0.130)
3.700(0.146)
4.300(0.169)
4.700(0.185)
1.000(0.039)
1.400(0.055)
4.400(0.173)
4.800(0.189)
3.430(0.135)
MIN
0.320(0. 013)
0.510(0. 020)
0.000(0.000)
0.380(0.015)
Data Sheet
14
BCD Semiconductor Manufacturing Limited
ADJUSTABLE PRECISION SHUNT REGULATORS AS431
Dec. 2012 Rev. 2. 6
Mechanical Dimensions (Continued)
TO-92(Ammo Packing) Unit: mm(inch)
Φ
4.300(0.169)
4.700(0.185)
12.500(0.492)
14.500(0.571)
2.540(0.100)
Typ
1.270(0.050)
Typ
0. (0.015)
0.550(0.022 )
4.400(0.173
)
4.800(0.189
)
3. 430(0. 135)
MIN
0. 320(0. 013)
0. 510(0.020)
0.000(0.000)
0. 380(0. 015)
MAX
1. 100(0. 043
1. 400(0. 055
)
3.300(0.130)
3.800(0.150)
Φ
1.600(0.063)
)
380
2.500(0.098
)
4.000(0.157
)
13. 000(0. 512
)
15.000(0.591
)
Data Sheet
15
Dec. 2012 Rev. 2. 6 BCD Semiconductor Manufacturing Limited
ADJUSTABLE PRECISION SHUNT REGULATORS AS431
Mechanical Dimensions (Continued)
SOT-23 Unit: mm(inch)
2.300(0.091)
2.500(0.098)
1.200(0.047)
1.400(0.055)
0.920(0.036)
0.980(0.039)
0.300(0.012)
0.500(0.020)
1.900(0.075)REF
2.800(0.110)
3.000(0.118)
2.0°
3.0 °
0.500(0.020)
0.700(0.028)
1.050(0.041)REF 0.020(0.001)
0.100(0.004)
0.900(0.035)
1.100(0.043)
4×R0.100(0.004)
7.0°
7.0°
0.550(0.022)REF
0.200(0.008)MIN
0.100(0.004) GAUGE PLANE
0.080(0.003)
0.150(0.006)
R0.100(0.004)
0.0°~10.0°
Data Sheet
16
BCD Semiconductor Manufacturing Limited
ADJUSTABLE PRECISION SHUNT REGULATORS AS431
Dec. 2012 Rev. 2. 6
Mechanical Dimensions (Continued)
SOT-23-5 Unit: mm(inch)
2.820(0.111)
2.650(0.104)
1.500(0.059)
0.000(0.000)
0.300(0.012)
0.950(0.037)
0.900(0.035)
0.100(0.004)
0.200(0.008)
0.300(0.012)
8°
0°
3.020(0.119)
1.700(0.067)
2.950(0.116)
0.400(0.016)
0.150(0.006)
1.300(0.051)
0.200(0.008)
0.600(0.024)
1.800(0.071)
2.000(0.079)
0.700(0.028)
REF
TYP
1.450(0.057)
MAX
Data Sheet
17
Dec. 2012 Rev. 2. 6 BCD Semiconductor Manufacturing Limited
ADJUSTABLE PRECISION SHUNT REGULATORS AS431
Mechanical Dimensions (Continued)
SOT-89 Unit: mm(inch)
45
1.030(0.041)REF
1.550(0.061)REF
4.400(0.173)
4.600(0.181)
0.900(0.035)
1.100(0.043)
3.950(0.156)
4.250(0.167)
3.000(0.118)
TYP
0.480(0.019)
2.300(0.091)
2.600(0.102)
0.320(0.013)
0.520(0.020)
310
2.060(0.081)REF
1.400(0.055)
1.600(0.063)
0.350(0.014)
0.450(0.018)
R0.150(0.006)
3
10
1.500(0.059)
0.320(0.013)REF
1.620(0.064)REF
2.210(0.087)REF
0.320(0.013)
0.520(0.020)
1.800(0.071)
IMPORTANT NOTICE
BCD Semiconductor Manufacturing Limited reserves the right to make changes without further notice to any products or specifi-
cations herein. BCD Semiconductor Manufacturing Limited does not assume any responsibility fo r use of any its products for any
particular purpose, nor does BCD Semiconductor Man ufacturing Limited assume any liability arising out of the application or use
of any its products or circuits. BCD Semiconductor Manufacturing Limited does not convey any license under its patent rights or
other rights nor the rights of others.
- Wafer Fab
Shanghai SIM-BCD Semiconductor Manufacturing Limited
800, Yi Shan Road, Shanghai 200233, China
Tel: +86-21-6485 1491, Fax: +86-21-5450 0008
BCD Semiconductor Manufacturing Limited
MAIN SITE
REGIONAL SALES OFFICE
Shenzhen Office
Shanghai SIM-BCD Semiconductor Manufacturing Co., Ltd. Shenzhen Office
Advanced Analog Circuits (Shanghai) Corporation Shenzhen Office
Room E, 5F, Noble Center, No.1006, 3rd Fuzhong Road, Futian District, Shenzhen 518026, China
Tel: +86-755-8826 7951
Fax: +86-755-8826 7865
Taiwan Office
BCD Semiconductor (Taiwan) Company Limited
4F, 298-1, Rui Guang Road, Nei-Hu District, Taipei,
Taiwan
Tel: +886-2-2656 2808
Fax: +886-2-2656 2806
USA Office
BCD Semiconductor Corporation
30920 Huntwood Ave. Hayward,
CA 94544, U.S.A
Tel : +1-510-324-2988
Fax: +1-510-324-2788
- IC Design Group
Advanced Analog Circuits (Shanghai) Corporation
8F, Zone B, 900, Yi Shan Road, Shanghai 200233, China
Tel: +86-21-6495 9539, Fax: +86-21-6485 9673
BCD Semiconductor Manufacturing Limited
http://www.bcdsemi.com
BCD Semiconductor Manufacturing Limited
IMPORTANT NOTICE
BCD Semiconductor Manufacturing Limited reserves the right to make changes without further notice to any products or specifi-
cations herein. BCD Semiconductor Manufacturing Limited does not assume any responsibility for use of any its products for any
particular purpose, nor does BCD Semiconductor Manufacturing Limited assume any liability arising out of the application or use
of any its products or circuits. BCD Semiconductor Manufacturing Limited does not convey any license under its patent rights or
other rights nor the rights of others.
- Wafer Fab
Shanghai SIM-BCD Semiconductor Manufacturing Co., Ltd.
800 Yi Shan Road, Shanghai 200233, China
Tel: +86-21-6485 1491, Fax: +86-21-5450 0008
MAIN SITE
REGIONAL SALES OFFICE
Shenzhen Office
Shanghai SIM-BCD Semiconductor Manufacturing Co., Ltd., Shenzhen Office
Unit A Room 1203, Skyworth Bldg., Gaoxin Ave.1.S., Nanshan District, Shenzhen,
China
Tel: +86-755-8826 7951
Fax: +86-755-8826 7865
Taiwan Office
BCD Semiconductor (Taiwan) Company Limited
4F, 298-1, Rui Guang Road, Nei-Hu District, Taipei,
Taiwan
Tel: +886-2-2656 2808
Fax: +886-2-2656 2806
USA Office
BCD Semiconductor Corp.
30920 Huntwood Ave. Hayward,
CA 94544, USA
Tel : +1-510-324-2988
Fax: +1-510-324-2788
- Headquarters
BCD Semiconductor Manufacturing Limited
No. 1600, Zi Xing Road, Shanghai ZiZhu Science-based Industrial Park, 200241, China
Tel: +86-21-24162266, Fax: +86-21-24162277