ADJUSTABLE PRECISION
ZENER SHUNT REGULATOR
Issue 1 - NOVEMBER 1998
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 nt
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 ov e me nt 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.
ZR431L
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
100µA to 25mA current sink capability
Low output noise
APPLICATIONS
Shunt regulator
Series regulator
Voltage monitor
Over voltage/ under voltage protection
Switch mode power supplies
SCHEMATIC DIAGRAM
V
Z
V
ref
G
nd
ZR431L
ABSOLUTE MAXIMUM RATING
Cathode Voltage (V
Z
)
10V
Cathode Current
50mA
Operating Temperature
-40 to 85°C
Storage Temperature
-55 to 125°C
Recommended Operating Conditions
Min
Max
Cathode Voltage
V
REF
10V
Cathode Current
100µA 25mA
Power Dissipation (T
amb
=25°C,
T
jmax
=150°C)
SOT23
330mW
TO92
600mW
ELECTRICAL CHARACTERISTICS TEST CONDITIONS (Unless otherwise stated):T
amb
=25°C
VALUE
PARAMETER
Reference Voltage
SYMBOL MIN
2.5% V
ref
1.0%
V
dev
TYP
MAX UNITS CONDITIONS
1.271
1.252
8.0
V
mV
I
L
=10mA (Fig1), V
Z
=V
ref
I
L
=10mA, V
Z
=V
ref
T
a
=full range (Fig1)
1.209 1.24
1.228 1.24
4.0
Deviation of Reference
Input Voltage over
Temperature
Ratio of the change in
Reference Voltage to the
Change in Cathode
Voltage
Reference Input Current
Deviation of Reference
Input Current over
Temperature
Minimum Cathode
Current for Regulation
Off-state Current
Dynamic Output
Impedance
∆
V
ref
∆
V
Z
0.5
2.0
mV/V V
Z
from V
ref
to 10V
I
Z
=10mA (Fig2)
I
ref
∆
I
ref
0.02
0.11
0.02
0.4
0.2
µA
µA
R1=10k,R2=O/C,l
L
=10mA(Fig2)
R1=10k, R2=O/C, I
L
=10mA
T
a
=full range (Fig2)
I
Zmin
I
Zoff
R
Z
30
10
0.25
100
30
2
µA
µA
Ω
V
Z
=10V, V
ref
=0V (Fig3)
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:
Vmax
V
dev
x
1000000
V
ref
(
ppm
⁄
°C
)=
V
ref
(
T1−T2)
The dynamic output impedance, Rz, is defined
Vmin
∆
V
Z
R
Z
=
as:
∆
I
Z
When the device is programmed with two
Vdev = Vmax - Vmin
external resistors, R1 and R2, (fig 2) , the
dynamic output impedance of the overall
circuit, R’, is defined as:
R1
R
’
=
R
z
(
1+
)
T1
T2
R2
Temperature
ZR431L
CONNECTION DIAGRAMS
SOT23 Package Suffix – F
TO92 Package Suffix – C
Top View
Bottom View
ORDERING INFORMATION
Part
Number
ZR431LF02
ZR431LF01
ZR431LC02
ZR431LC01
Package Tol
%
SOT23
SOT23
TO92
TO92
2.5
1
2.5
1
Part Mark
43L
43M
ZR431L02
ZR431L01
ZR431L
TYPICAL CHARACTERISTICS
140
Vref = Vz
0
Iz= 10mA
130
120
110
100
90
80
-40
-1
-2
-3
-4
-5
-6
-7
-8
-9
Iz 10mA
-20
0
20
40
60
80
0
2
4
6
8
10
12
Temperature (° C)
Cathode Voltage (V)
Reference Current v Temperature
26
Vref = Vz
Change in V
ref
v Cathode Voltage
100
Vref = Vz
1mA
24
22
20
18
16
14
-40
0.1
100
1
10
10mA
-20
0
20
40
60
80
1k
10k
100k
Temperature (° C)
Frequency (Hz)
Cathode Current v Temperature
Dynamic Impedance v Frequency
1.244
1.242
1.240
1.238
1.236
Iz= 10mA
1.0
TO92
SOT23
1.234
1.232
-40
0
-20
0
20
40
60
80
25
50
75
85
100
Temperature (° C)
Ambient Temprature (° C)
Reference Voltage v Temperature
Power Dissipation Derating
ZR431L
DC TEST CIRCUITS
Input
I
L
V
Z
Input
I
L
V
Z
Input
V
Z
I
HAB
I
Z
47nF
R1
I
HAB
I
Z
47nF
I
zoff
47nF
V
ref
R2
V
ref
Fig 1 – Test Circuit for V
z
=V
ref
Fig 2 – Test Circuit for V
z
>V
ref
Fig 3 – Test Circuit for Off
State current
1-42
