WSL
431
Adjustable Precision Shunt Regulator
Features
Precise Reference Voltage to 2.505V
Guaranteed 0.5%, 1% and 2% Reference
Voltage Tolerance
Sink Current Capability, 1mA to 100mA
Quick
Turn-on
Adjustable Output Voltage, Vo
= V
ref
to 20V
Low Operational Cathode Current, 150A
Typical
0.1 Typical Output Impedance
SOT-89 , TO-92 and SOT-23 Packages
Applications
Linear Regulators
Adjustable Power Supply
Switching Power Supply
REF ANODE CATHODE
General Description
The WSL431 is a 3 terminal adjustable voltage
reference with specified thermal stability over
applicable commercial temperature ranges.
Output voltage may be set to any value between
Vref (2.505V) and 20V with two external
resistors (see Figure 2).
When used with a photocoupler, the WSL431 is
an ideal voltage reference in isolated feedback
circuits for 2.505V to 12V switching-mode
power supplies.
This device has a typical output impedance of
o.1. Active output circuitry provides a very
sharp turn-on characteristic, making the
WSL431 excellent replacements for zener diodes
in many applications, including on-board
Regulation and adjustable power supplies.
SOT-89 (Top View)
TO-92
SOT-23 (Top View)
Winson reserves the right to make changes to improve reliability or manufacturability.
Winson, Jan. 2000 (Rev. C)
WSL
431
Ordering Information
WSL431-XP Elec. Grad
2: 0.5% Reference Voltage Tolerance
3: 1% Reference Voltage Tolerance
4: 2% Reference Voltage Tolerance
Package Code
A: TO-92
C: SOT-23
N: SOT-89
Elec. Grade
Package Code
Symbol
REF
ANODE CATHODE
Functional Diagram
Winson reserves the right to make changes to improve reliability or manufacturability.
Winson, Jan. 2000 (Rev. C)
WSL
431
Absolute Maximum Ratings
Symbol
Parameter
Rating
Unit
V
KA
Cathode voltage
26
V
I
K
Continuous cathode current range
150
mA
I
ref
Reference current range
3
mA
T
A
Ambient temperature range
0 to 85
C
T
J
Junction temperature range
0 to 125
C
T
STG
Storage Temperature Range
-65 to 150
C
T
SO
Lead temperature range, T
s
(Soldering,
10sec)
260
C
Electrical Characteristics T
A
= 25C (unless otherwise noted)
WSL431
Symbol Parameter
Test
Conditions
Min. Typ. Max.
WSL431B 2.4925 2.505
2.5175
WSL431C 2.480 2.505
2.530
V
ref
V
KA
=Vref, I
K
=10mA.
WSL431D 2.455 2.505
2.555
Unit
V
ref
/T
Reference Voltage Drift over
Temp. range
T
A
=0 to 85C
*1
, I
k
=10mA.
4
20
mV
V
ref
/V
KA
Voltage Ration
(open loop gain)
I
K
=10 mA, V
KA
=Vref to 20V
*2
- 4
- 1.6
mV/
V
I
ref
Reference Current
I
K
=10mA,
R
1
=10K, R
2
=open
*2
0.4
3.5
A
I
ref
/T
Reference Current Drift
I
K
=10 mA,
R
1
=10K, R
2
=open, TA=0 to
85C
*2
0.4
1.2
A
I
K(min)
Min. Cathode Current
V
KA
=Vref
*1
0.15
0.4
mA
I
K(off)
Off-state Cathode Current
V
KA
=20V, Vref=0V
*3
0.1
1
A
z
KA
Dynamic Impedance
V
KA
=Vref, IK=1 mA to 100mA,
f=1k Hz*1
-0.4 -0.1
Notes:
*1
: use Figure 1
*2
: use Figure 2
*3
: use Figure 3
Winson reserves the right to make changes to improve reliability or manufacturability.
Winson, Jan. 2000 (Rev. C)
WSL
431
Test figures
Figure 1. Test Circuit for V
KA
=V
REF
Figure 2. Test Circuit for V
KA
<V
REF
,
V
O
=V
KA
=V
REF
V
O
=V
KA
=V
REF
(1+R
1
/R
2
)+I
REF
R
1
Figure 3. Test Circuit for I
k(off)
Winson reserves the right to make changes to improve reliability or manufacturability.
Winson, Jan. 2000 (Rev. C)
WSL
431
Winson reserves the right to make changes to improve reliability or manufacturability.
Winson, Jan. 2000 (Rev. C)
TYPICAL CHARACTERISTICS
Vref. vs Free-Air Temperature
2.475
2.48
2.485
2.49
2.495
2.5
2.505
2.51
2.515
2.52
2.525
20
30
40
50
60
70
80
90
100 110 120
o
C
Vr
ef
.
(
V
)
2.518 V
2.499 V
2.480 V
Iref vs Free-Air Temperature
0
0.1
0.2
0.3
0.4
0.5
0.6
20
30
40
50
60
70
80
90
100
110
120
o
C
Iref.
(
uA
)
Ik(off) vs Free-Air Temperature
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0
20
40
60
80
100
120
140
o
C
Ik
(o
ff) - (u
A)
Ratio of Delta Vref to Delta Vk vs Temperature
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
10
20
30
40
50
60
70
80
90
100
110
120
o
C
dVref/dVk (mv/v)
Cathode Current vs Cathode Voltage
-200
-100
0
100
200
300
400
500
600
700
800
-1
-0.5
0
0.5
1
1.5
2
2.5
3
V
KA
- V
I
KA
-
u
A
V
KA
=V
ref
T
A
=25C
I
min
WSL
431
Winson reserves the right to make changes to improve reliability or manufacturability.
Winson, Jan. 2000 (Rev. C)
Application schematic
5-Volt Precision Regulator
*R
b
should provide cathode current large than 0.4mA to maintain
WSL431work properly.
Figure 4.
Figure 5.
Figure 6.
WSL
431
Figure 7.
Figure 8.
Figure 9.
Winson reserves the right to make changes to improve reliability or manufacturability.
Winson, Jan. 2000 (Rev. C)
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