SCHEMATIC DIAGRAM
DEVICE DESCRIPTION
The ZR431L 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 n t
temperature stability and output current
handling capability up to 25mA. The output
voltage may be set to any chosen voltage
between 1.24 and 10 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 m e n t i n z e n e r
performance.
The ZR431L is particularly used in the
feedback control loop of switch mode power
supplies. In this application the device 1.24
volt reference enables the generation of low
voltage supplies, typically 3.3 volts or 3 volts.
FEATURES
Surface mount SOT23 package
TO92 package
2.5% and 1% tolerance
Maximum temperature coefficient 50
ppm/C
Temperature compensated for
operation over the full temperature
range
Programmable output voltage
100
A to 25mA current sink capability
Low output noise
APPLICATIONS
Shunt regulator
Series regulator
Voltage monitor
Over voltage/ under voltage protection
Switch mode power supplies
ADJUSTABLE PRECISION
ZENER SHUNT REGULATOR
Issue 1 - NOVEMBER 1998
ZR431L
V
Z
G
nd
V
ref
ZR431L
ABSOLUTE MAXIMUM RATING
Cathode Voltage (V
Z
)
10V
Cathode Current
50mA
Operating Temperature
-40 to 85C
Storage Temperature
-55 to 125C
Recommended Operating Conditions
Min
Max
Cathode Voltage
V
REF
10V
Cathode Current
100
A 25mA
Power Dissipation (T
amb
=25C,
T
jmax
=150C)
SOT23
330mW
TO92
600mW
ELECTRICAL CHARACTERISTICS TEST CONDITIONS (Unless otherwise stated):T
amb
=25C
PARAMETER
SYMBOL
VALUE
UNITS CONDITIONS
MIN
TYP
MAX
Reference Voltage 2.5%
1.0%
V
ref
1.209
1.228
1.24
1.24
1.271
1.252
V
I
L
=10mA (Fig1), V
Z
=V
ref
Deviation of Reference
Input Voltage over
Temperature
V
dev
4.0
8.0
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
0.5
2.0
mV/V V
Z
from V
ref
to 10V
I
Z
=10mA (Fig2)
Reference Input Current
I
ref
0.02
0.11
0.4
A
R1=10k, R2=O/C, l
L
=10mA (Fig2)
Deviation of Reference
Input Current over
Temperature
I
ref
0.02
0.2
A
R1=10k, R2=O/C, I
L
=10mA
T
a
=full range (Fig2)
Minimum Cathode
Current for Regulation
I
Zmin
30
100
A
Off-state Current
I
Zoff
10
30
A
V
Z
=10V, V
ref
=0V (Fig3)
Dynamic Output
Impedance
R
Z
0.25
2
V
Z
=V
ref
(Fig1), f=0Hz,
I
L
=10mA
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
(
T
1
-
T
2
)
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
+
R
1
R
2
)
Vmax
Vmin
T1
T2
Vdev = Vmax - Vmin
Temperature
CONNECTION DIAGRAMS
ZR431L
SOT23 Package
Suffix F
Top
View
ORDERING INFORMATION
Part
Number
Package Tol
%
Part Mark
ZR431LF02
SOT23
2.5
43L
ZR431LF01
SOT23
1
43M
ZR431LC02
TO92
2.5
ZR431L02
ZR431LC01
TO92
1
ZR431L01
TO92 Package Suffix C
Bottom
View
ZR431L
Reference Current v Temperature
Temperature ( C)
0
20
60
40
80
90
140
130
120
110
100
-40
-20
80
Change in V
ref
v Cathode Voltage
Cathode Voltage (V)
4
12
10
-7
-1
-2
-3
-4
-5
0
0
-6
2
6
8
-8
-9
Cathode Current v Temperature
Temperature ( C)
0
20
60
40
14
16
26
24
22
20
18
-40
-20
80
Dynamic Impedance v Frequency
Frequency (Hz)
1k
10k
100k
0.1
10
1
100
100
Power Dissipation Derating
Ambient Temprature ( C)
50
100
75
0
25
1.0
85
Reference Voltage v Temperature
Temperature ( C)
0
20
60
40
1.240
1.236
-40
-20
80
1.234
1.232
1.238
1.242
1.244
Vref = Vz
Iz= 10mA
Iz 10mA
Vref = Vz
Vref = Vz
1mA
10mA
TO92
SOT23
Iz= 10mA
TYPICAL CHARACTERISTICS
ZR431L
Input
V
V
I
Z
Z
ref
I
L
I
HAB
47nF
Fig 1 Test Circuit for V
z
=V
ref
DC TEST CIRCUITS
Input
V
V
I
Z
Z
ref
I
HAB
R1
R2
I
L
47nF
Fig 2 Test Circuit for V
z
>V
ref
Input
V
I
Z
zoff
47nF
Fig 3 Test Circuit for Off
State current
1-42
ZR431L
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
PROTECTION CIRCUIT
Low limit =
High limit =
1 +
R1A
R2A
Vref
R2
R1
Vout =
Vref
1 +
R1
R2
Vref
SHUNT REGULATOR
V+
Vout
OUTPUT
APPLICATION CIRCUITS
ZR431L
Gain v Frequency
Frequency (Hz)
10k
100k
0
10
60
50
40
30
20
100
1k
Pulse Response
Time (
s)
200
300
500
400
0
2.0
1.0
0
5.0
2.5
0
100
Stability Boundary Conditions
Load Capacitance(F)
1n
10n
1
0
5
30
25
20
15
10
10p
100p
.1
10
1
Z
47k
V
Z
Test Circuit for Open Loop Voltage Gain
47k
10
.
"
+
-
I
Z
= 10mA, T
A
= 25C
Test Circuit for Pulse Response
Input Monitor
V
Z
120
50
Pulse
Generator
T
A
= 25C
Test Circuit for Stability
Boundary Conditions
Input
150
10k
V
ref
< V
Z
< 10, I
Z
= 10mA, T
A
= 25C
8
Z
1
Z
100
F
STABLE
STABLE
UNSTABLE
Iz =10mA
INPUT
Single
Pulse
Repetitive
Pulse
Vz
TYPICAL CHARACTERISTICS
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