SEAWARD
ELECTRONICS
Adjustable Precision
Shunt Regulator
Features
Low voltage operation (2.5V)
SE431
Description
The SE431 is a low voltage three terminal
adjustable shunt regulator with a guaranteed thermal
stability over applicable temperature ranges. The output
voltage can be set to any value between V
REF
(approximately 2.5 V) to 18V with two external resistors.
This device has a typical output impedance of 0.2Ω.
Active output circuitry provides a very sharp turn on
characteristic, making this device excellent replacement
for Zener diodes in many applications.
The SE431 is characterized for operation from 0
o
C
to 105
o
C, and five package options (SOT-23-3, SOT-23-5,
SOP-8, TO-92 and SOT-89) allow the designer the
opportunity to select the proper package for their
applications.
Adjustable output voltage V
0
= V
REF
to 18V
Wide operating current range 120µA to 100mA
Low dynamic output impedance 0.2Ω (Typ.).
Trimmed bandgap design up to + 0.5%.
ESD rating is 5.5KV(Per MIL-STD-883D).
Available in Lead Free Packages.
Application
Linear Regulators
Adjustable Supplies
Switching Power Supplies
Battery Operated Computers
Instrumentation
Computer Disk Drives
Block Diagram
Symbol Diagram
Cathode
Ref
Cathode
+
-
Vref
Anode
Ref
Anode
All contents are subject to change without prior notice.
© Seaward Electronics, Inc., 2005. • www.seawardinc.com • Page 1
SEAWARD
ELECTRONICS
Adjustable Precision
Shunt Regulator
SE431
Lead-Free Package
Marking Information
Package
SOT-23-3
SC59-3L
SOT-23-3
SOT-23-5L
SOP-8
Marking
SE431W
S431W
(SE431S)
SE431W
SE431
YYWW
SE431
YYWW
SE431
YYWW
YY is the year of production. 04 means the
product is manufactured in year of 2004.
WW
is
the
week
of
Lead-free
package
is
Production Year Code
Starting with S, a bar on top of S is for production
year 2001, and underlined S is for year 2002.
The next character is marked on top for 2003, and
underlined for 2004. The naming pattern continues
with consecutive characters for later years.
Production Week Code
A-Z: 1-26
a-z: 27-52
Lead-free package is
indicated by a dot on
top of the week code.
SOT-89
production.
26 means the
product is manufactured in
the 26
th
week.
indicated by LF after
YYWW.
TO-92
Pin Configuration
SOT-23-3
SOT-23-3L (SC59-3L)
SOT-23-3
(Order as SE431S)
SOT-23-5L
TO-92
SOP-8
(Top View)
SOT-89
All contents are subject to change without prior notice.
© Seaward Electronics, Inc., 2005. • www.seawardinc.com • Page 2
SEAWARD
ELECTRONICS
Adjustable Precision
Shunt Regulator
SE431
Absolute Maximum Ratings
Parameter
Cathode Voltage
Continuous Cathode Current
Reference Current
Operating Junction Temperature Range
Storage Temperature Range
Symbol
V
KA
I
KA
I
REF
T
J
T
STG
Maximum
18
150
10
150
-65 to 150
120 (SOT-89)
230 (SOT-23-3)
Units
V
mA
mA
°C
°C
Thermal Resistance
θ
JA
230 (SOT-23-5L)
150 (SOP-8)
220 (TO-92)
°C/W
Lead Temperature (Soldering) 10 seconds
T
LEAD
260
°C
Electrical Characteristics
TEST
PARAMETER
0.5%
Reference Voltage
1%
2%
Deviation of reference voltage over
full temperature range
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
regulation
Off-state cathode current
Dynamic impedance
for
I
MIN
I
OFF
Z
KA
1
3
1
V
KA
= V
REF
V
KA
= 18V, V
REF
= 0
I
KA
= 1mA to 100mA, V
KA
=
V
REF
, f
≤
1kH
Z
--
--
--
0.2
0.1
0.2
1
1
0.7
mA
µA
Ω
I
I(dev)
2
V
I(dev)
∆
V
REF
________
∆
V
KA
I
REF
2
2
1
V
KA
= V
REF
, I
KA
= 10mA
T
A
= 0°C to 105°C
I
KA
= 10mA,
∆V
KA
= 10 V - V
REF
I
KA
= 10mA,
R1=10kΩ, R2 =
∞
I
KA
= 10mA, R1=10kΩ,
R2 =
∞,
T
A
= 0°C to 105°C
V
REF
1
V
KA
= V
REF
, I
KA
= 10mA
SYMBOL
CIRCUIT
2483
2470
2445
--
2495
2495
2495
4
2507
2520
2545
25
mV
mV
TEST CONDITIONS
MIN
TYP
MAX
UNIT
--
-1.4
-2.7
mV/V
--
2
4
µA
--
0.4
1.2
µA
All contents are subject to change without prior notice.
© Seaward Electronics, Inc., 2005. • www.seawardinc.com • Page 3
SEAWARD
ELECTRONICS
Adjustable Precision
Shunt Regulator
SE431
Typical Performance Characteristics
CATHODE CURRENT
Vs.
CATHODE VOLTAGE
150
125
100
800
CATHODE CURRENT
Vs.
CATHODE VOLTAGE
V
K A
= V ref
T
A
= 25
o
C
600
V
KA
= Vref
T
A
= 25
o
C
Cathode Current (mA)
75
50
25
0
-25
-50
-75
Cathode Current (µA)
-2
-1
0
1
2
3
400
200
0
-100
- 200
-1
0
1
2
3
Cathode Voltage (V)
Cathode Voltage (V)
REFERENCE VOLTAGE
Vs.
JUNCTION TEMPERATURE
2520
3
REFERENCE INPUT CURRENT
Vs.
JUNCTION TEMPERATURE
R1 = 10k
Ω
R2 =
∞
I
KA
=10mA
Reference Current (µA)
0
20 40
60
80 100 120
o
Reference Voltage (mV)
2515
2510
2505
2500
2495
2490
2485
V
KA
=Vref
I
KA
=10mA
2. 5
2
1. 5
1
0. 5
0
- 20
2480
- 60 - 40 - 20
0
20
40
60
80
100
120
Junction Temperature ( C)
Junction Temperature (
o
C)
All contents are subject to change without prior notice.
© Seaward Electronics, Inc., 2005. • www.seawardinc.com • Page 4
SEAWARD
ELECTRONICS
Adjustable Precision
Shunt Regulator
SE431
V
KA
Test Circuits
Input
V
KA
Input
I
KA
V
KA
Input
I
off
I
KA
R1
Iref
Vref
R2
Vref
R1
V
KA
= Vref (1+
) + Iref x R1
R2
Test Circuit 1:
V
KA
= V
REF
Test Circuit 2:
V
KA
> V
REF
Test Circuit 3:
Off State Current
Application Diagram
V
IN
R
V
OUT
R1
Vref
R2
SE431
V
OUT
= Vref (1+
R1
)
R2
GND
Thermal Consideration
Package
Power Rating
(T
A
=25
°C
)
SOT-23-3 (θ
JA
=230°C/W)
SOT-23-5L (θ
JA
=230°C/W)
TO-92 (θ
JA
=220°C/W)
1. Maximum junction temperature is 125°C
2.
θ
JA
is measured with packages mounted onboard under still-air condition with 1W power applied.
3. Power rating is calculated using P
D
= (T
J
– T
A
) /θ
JA,
where T
J
denotes junction temperature and T
A
denotes ambient temperature.
Power Rating
(T
A
=50
°C
)
326mW
326mW
341mW
Power Rating
(T
A
=70
°C
)
239mW
239mW
250mW
435mW
435mW
455mW
All contents are subject to change without prior notice.
© Seaward Electronics, Inc., 2005. • www.seawardinc.com • Page 5
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