A Product Line of
Diodes Incorporated
AS431I
LOW CATHODE CURRENT ADJUSTABLE PRECISION SHUNT REGULATOR
Description
The AS431I is a three-terminal adjustable shunt regulator with
guaranteed thermal stability over a full operation range. It features
sharp turn-on characteristics, low temperature coefficient and low
output impedance, which make it ideal substitute for Zener diode in
applications such as switching power supply, charger and other
adjustable regulators.
The output voltage of AS431I can be set to any value between V
REF
(2.5V) and the corresponding maximum cathode voltage (36V).
The AS431I is offered in two grade initial voltage tolerance at +25
o
C,
0.5%, and 1%.
This IC is available in 3 packages: TO-92 (bulk or ammo packing),
SOT-23 and SOT-89.
Features
Programmable Precise Output Voltage from 2.5V to 36V
High Stability Under Capacitive Load
Low Minimum Cathode Current for Regulation: 10µA (Typ.), 50µA
(Max.)
Low Temperature Deviation: 4.5mV Typical
Sink Current Capacity from 50µA to 100mA
Low Output Noise
Wide Operating Range: -40 to +125
o
C
Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
Halogen and Antimony Free. “Green” Device (Note 3)
Applications
Charger
Voltage Adapter
Switching Power Supply
Graphic Card
Precision Voltage Reference
Notes:
1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.
2. See http://www.diodes.com/quality/lead_free.html for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green"
and Lead-free.
3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and
<1000ppm antimony compounds.
Pin Assignments
(Top View)
(Top View)
(Top View)
ANODE
3
1
REF
2
CATHODE
SOT-23
1
2
3
1
2
3
REF ANODE CATHODE
SOT-89 (Option 1)
REF ANODE CATHODE
SOT-89 (Option 2)
AS431I
Document number: DS36816 Rev. 3 - 2
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July 2014
© Diodes Incorporated
A Product Line of
Diodes Incorporated
AS431I
Pin Assignments
(Cont.)
(Top View)
(Top View)
3 CATHODE
2 ANODE
1 REF
3
CATHODE
ANODE
REF
2
1
TO-92 (Bulk Packing)
TO-92 (Ammo Packing)
Typical Applications Circuit
V
OUT
=(1+R1/R2)*V
REF
Shunt Regulator
V
OUT
=(1+R2/R3)*V
REF
High Current Shunt Regulator
AS431I
Document number: DS36816 Rev. 3 - 2
2 of 17
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July 2014
© Diodes Incorporated
A Product Line of
Diodes Incorporated
AS431I
Typical Applications Circuit
(Cont.)
I
OUT
=V
REF
/R2+ I
KA
Current Source or Current Limit
Precision 5V 1A Regulator
PWM Converter with Reference
AS431I
Document number: DS36816 Rev. 3 - 2
3 of 17
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July 2014
© Diodes Incorporated
A Product Line of
Diodes Incorporated
AS431I
Functional Block Diagram
CATHODE
REF
+
-
V
REF
ANODE
Absolute Maximum Ratings
(Note 4)
Symbol
V
KA
I
KA
I
REF
Parameter
Cathode Voltage
Cathode Current Range (Continuous)
Reference Input Current Range
TO-92
P
D
Power Dissipation
SOT-89
SOT-23
T
J
T
STG
ESD
Junction Temperature
Storage Temperature Range
ESD (Human Body Model)
+150
-65 to +150
2000
Rating
40
-100 to 150
10
770
770
370
º
C
º
C
V
mW
Unit
V
mA
mA
Note 4:
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.
Recommended Operating Conditions
Symbol
V
KA
I
KA
T
A
Parameter
Cathode Voltage
Cathode Current
Operating Ambient Temperature Range
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Min
V
REF
0.05
-40
Max
36
100
+125
Unit
V
mA
º
C
July 2014
© Diodes Incorporated
AS431I
Document number: DS36816 Rev. 3 - 2
A Product Line of
Diodes Incorporated
AS431I
Electrical Characteristics
Symbol
Parameter
0.5%
V
REF
Reference Voltage
1.0%
0 to +70°
C
∆V
REF
Deviation of Reference Voltage
Over Full Temperature Range
4
V
KA
= V
REF
,
I
KA
= 10mA
-40 to +85°
C
-40 to +125°
C
∆V
REF
∆V
KA
I
REF
∆I
REF
I
KA
(Min)
I
KA
(Off)
Z
KA
Ratio of Change in Reference
Voltage to the Change in Cathode
Voltage
Reference Current
Deviation of Reference Current
Over Full Temperature Range
Minimum Cathode Current for
Regulation
Off-state Cathode Current
Dynamic Impedance
∆V
KA
=
V
REF
10V
to
4
V
KA
= V
REF
, I
KA
= 10mA
2.475
–
–
–
–
–
–
–
–
–
–
–
–
–
2.500
4.5
4.5
4.5
-1.0
-0.5
0.035
0.03
10
0.05
0.15
68
29
113
2.525
8
10
16
-2.7
-2.0
0.5
0.3
50
1.0
0.5
–
–
–
°
C/W
µA
µA
µA
µA
Ω
mV
(Operating Conditions: T
A
= +25º unless otherwise specified.)
C,
Test
Circuit
Conditions
Min
2.487
Typ
2.500
Max
2.512
Unit
V
5
I
KA
= 10mA
mV/V
∆V
KA
= 36V to 10V
5
5
4
6
4
I
KA
= 10mA, R1 = 10KΩ, R2 = ∞
I
KA
= 10mA, R1 = 10KΩ, R2 = ∞,
T
A
= -40 to +125°
C
V
KA
= V
REF
V
KA
= 36V, V
REF
= 0
V
KA
= V
REF
, I
KA
= 1 to 100mA,
f ≤ 1.0KHz
TO-92
θ
JC
Thermal Resistance
–
SOT-89
SOT-23
AS431I
Document number: DS36816 Rev. 3 - 2
5 of 17
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July 2014
© Diodes Incorporated
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