ADJUSTABLE PRECISION
ZENER SHUNT REGULATOR
ISSUE 4 SEPTEMBER 2000
ZR431
DEVICE DESCRIPTION
The ZR431 is a three terminal adjustable
s h u n t r e g u l a t o r o f f e r i n g e x c e l l e nt
temperature stability and output current
handling capability up to 100mA. The output
voltage may be set to any chosen voltage
between 2.5 and 20 volts by selection of two
external divider resistors.
The devices can be used as a replacement
for zener diodes in many applications
r e q u i r i n g a n i m p r o v e me n t i n z e n e r
performance.
FEATURES
Surface mount SO8, SOT223 and
SOT23 packages
TO92 package
2%, 1 % and 0.5% tolerance
Max. temperature coefficient 55 ppm/C
Temperature compensated for operation
over the full temperature range
Programmable output voltage
50
A to 100mA current sink capability
Low output noise
APPLICATIONS
Shunt regulator
Series regulator
Voltage monitor
Over voltage/ under voltage protection
Switch mode power supplies
V
Z
G
nd
V
ref
SCHEMATIC DIAGRAM
4-189
78
ZR431
ABSOLUTE MAXIMUM RATING
Cathode Voltage (V
Z
)
20V
Cathode Current
150mA
Operating Temperature
-40 to 85C
Storage Temperature
-55 to 125C
Recommended Operating Conditions
Min
Max
Cathode Voltage
Vref
20V
Cathode Current
50
A 100mA
Power Dissipation (T
amb
=25C,T
jmax
=150C)
SOT23
330mW
TO92
780mW
SOT223
2W
SO8
780mW
ELECTRICAL CHARACTERISTICS TEST CONDITIONS (Unless otherwise stated):T
amb
=25C
PARAMETER
SYMBOL
VALUE
UNITS CONDITIONS
MIN TYP MAX
Reference Voltage 2%
1%
(1)
0.5%
V
ref
2.45
2.475
2.489
2.50
2.50
2.50
2.55
2.525
2.513
V
I
L
=10mA (Fig1), V
Z
=V
ref
Deviation of Reference Input
Voltage over Temperature
V
dev
8.0
17
mV
I
L
=10mA, V
Z
=V
ref
T
a
=full range (Fig1)
Ratio of the change in
Reference Voltage to the
Change in Cathode
Voltage
V
ref
V
Z
-1.85 -2.7
mV/V
V
Z
from V
ref
to 10V
I
Z
=10mA (Fig2)
-1.0
-2.0
mV/V
V
Z
from 10V to 20V
I
Z
=10mA (Fig2)
Reference Input Current
I
ref
0.12 1.0
A
R1=10k, R2=O/C, l
L
=10mA
(Fig2)
Deviation of Reference
Input Current over
Temperature
I
ref
0.04 0.2
A
R1=10k, R2=O/C, I
L
=10mA
T
a
=full range (Fig2)
Minimum Cathode
Current for Regulation
I
Zmin
35
50
A
V
Z
=V
ref
(Fig1)
Off-state Current
I
Zoff
0.1
A
V
Z
=20V, V
ref
=0V (Fig3)
Dynamic Output Impedance R
Z
0.75
V
Z
=V
ref
(Fig1), f=0Hz
(1)
0.5% SOT23 only.
For definitions of reference voltage temperature coefficient and dynamic output impedance see
NOTES following DC TEST CIRCUITS
4-190
78
ZR431
TYPICAL CHARACTERISTICS
Cathode Current v Temperature
Dynamic Impedance v Frequency
Frequency (Hz)
100
10
1.0
0.1
100
1k
10k
100k
1M
D
ynamic
Impe
danc
e (
)
Temperature (C)
Minim
u
m Cat
h
o
de Curren
t
(
A)
24
-40
0
20
40
60
-20
80
26
28
30
32
34
36
38
V
ref
=V
Z
Reference Current v Temperature
Temperature (C)
Refere
nc
e
V
o
l
t
age
(V)
100
-40
0
20
40
60
-20
80
110
120
130
140
150
160
2.490
2.492
2.494
2.496
2.498
2.500
2.502
2.504
2.506
Ref
e
ren
c
e Cu
rre
n
t
(
n
A)
-40
0
20
40
60
-20
80
Reference Voltage v Temperature
Temperature (C)
I
Z
=10mA
V
ref
=V
Z
I
Z
=10mA
Change in Vr
ef
v Cathode Voltage
Cathode Voltage (V)
0
-25
Ch
ange
in Re
ferenc
e O
u
tp
ut
V
o
lt
age (
m
V)
5
10
15
20
-20
-15
-10
-5
0
I
Z
=10mA
V
ref
=V
Z
10mA
1mA
SOT223
SO8/TO92
SOT23
4-191
78
ZR431
TYPICAL CHARACTERISTICS
Gain v Frequency
Frequency (Hz)
Load Capacitance (F)
Stability Boundary Conditions
Time (
s)
Pulse Response
I
Z
15k
V
Z
Test Circuit for Open Loop Voltage Gain
8k25
9
F
230
+
-
I
Z
= 10mA, T
A
= 25C
Test Circuit for Stability Boundary Conditions
Input
150
10k
V
ref
< V
Z
< 20, I
Z
= 10mA, T
A
= 25C
V
Z
I
Z
Input Monitor
V
Z
Test Circuit for Pulse Response
220
50
Pulse
Generator
T
A
= 25C
60
40
20
0
100
1k
10k
100k
1M
Open
Loop V
o
lta
g
e Gai
n
(dB)
V
o
ltage Sw
ing
(V)
2.0
0
0
0.4
0.6
0.8
1.0
0.2
1.0
0
5.0
3.0
Repetitive pulse
Single pulse
V
Z
INPUT
STABLE
STABLE
0
10p
20
40
60
80
100
100p
1000p
0.01
0.1
1
C
athode C
u
rr
ent (mA
)
4-192
78
APPLICATION CIRCUITS
ZR431
R2
Vout = 1 +
R1
R2
Vref
SERIES REGULATOR
V+
Vout
R1
30
0.01F
Vref
Vout = 1 +
R1
R2
Vref
Vout = Vref + Vreg
MIN
OUTPUT CONTROL OF A
THREE TERMINAL FIXED REGULATOR
R2
R1
V+
Vout
Vref
ZSR***
In
Out
Common
R2
R1
V+
Vout
Vout =
Vref
1 +
R1
R2
Vref
HIGHER CURRENT SHUNT REGULATOR
V+
OUTPUT
INPUT
V
= 2.5V
TH
V
2V
on
V
= V+
off
SINGLE SUPPLY COMPARATOR
WITH TEMPERATURE
COMPENSATED THRESHOLD
R2A
R1A
V+
Vref
R2B
R1B
Vref
1 +
R1B
R2B
Vref
OVER VOLTAGE / UNDER VOLTAGE
Low limit =
High limit = 1 +
R1A
R2A
Vref
R2
R1
Vout =
Vref
1 +
R1
R2
Vref
SHUNT REGULATOR
V+
Vout
OUTPUT
4-193
78
I
L
Input
Fig 1 Test Circuit for V
z
=V
ref
DC TEST CIRCUITS
Fig 2 Test Circuit for V
z
>V
ref
Input
V
I
Z
zoff
Fig 3 Test Circuit for Off
State current
ZR431
4-194
NOTES
Deviation of reference input voltage, V
dev,
is defined as the maximum variation of the reference
input voltage over the full temperature range.
The average temperature coefficient of the reference input voltage, V
ref
is defined as:
V
ref
ppm
C
V
dev
x 1000000
V
ref
T1T2
The dynamic output impedance, Rz, is defined as:
R
Z
V
Z
I
Z
When the device is programmed with two external
resistors, R1 and R2, (fig 2) , the dynamic output
impedance of the overall circuit, R', is defined as:
R'
R
z
1
R1
R2
Vmax
Vmin
Vdev = Vmax - Vmin
78
ZR431
TO92 Package
Suffix C
Bottom
View
CONNECTION DIAGRAMS
SO8 Package
Suffix N8
Top
View
SOT223 Package
Suffix G
Top
View
Pin 4 floating or connected to pin 2
SOT23 Package
Suffix F
Top
View
Part Number
Package
Tol.
%
Part Mark
ZR431C01
TO92
1.0
ZR43101
ZR431C
TO92
2.0
ZR431
ZR431G01
SOT223
1.0
ZR43101
ZR431G
SOT223
2.0
ZR431
ZR431F005
SOT23
0.5
43R
ZR431F01
SOT23
1.0
43B
ZR431F
SOT23
2.0
43A
ZR431N801
SO8
1.0
ZR43101
ZR431N8
SO8
2.0
ZR431
ORDERING INFORMATION
4-195
78
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