ZR431L
Adjustable precision shunt regulator
Summary
Description
The ZR431L is a three terminal adjustable shunt regulator offering excellent
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 requiring an improvement in zener 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
•
•
•
•
•
2.5% and 1% tolerance
Max. temperature coefficient 50 ppm/°C
Temperature compensated for operation over -40 to 85°C
100mA to 25mA current sink capability
Surface mount SOT23 package
Applications
•
•
•
•
•
Switch mode power supplies
Shunt regulator
Series regulator
Voltage monitor
Over voltage / under voltage protection
Ordering information
Device
ZR431LF01TA
ZR431LF02TA
ZR431LC01STOB
ZR431LC02STOB
ZR431LC01L
ZR431LC02L
Pack
SOT23
SOT23
TO92
TO92
TO92
TO92
Part mark
43M
43L
ZR431L01
ZR431L02
ZR431L01
ZR431L02
Status
Active
Active
Obsolete
Obsolete
Obsolete
Obsolete
Quantity
per reel
3000
3000
1500
1500
Loose
Loose
Reel size
(inches)
7
7
TOL %
1
2.5
1
2.5
1
2.5
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ZR431L
Absolute maximum ratings
Parameter
Cathode voltage
Cathode current
Storage temperature
Junction temperature
T
STG
T
J
Symbol
V
Z
Limit
10
50
-55 to 105
-40 to 125
Unit
V
mA
°C
°C
Power dissipation
(at T
amb
= 25°C unless otherwise stated)
Package
SOT23
Value
330
Unit
mW
Recommended operating conditions
Parameter
Cathode voltage
Cathode current
Operating temperature
Min.
V
REF
100 A
-40°C
Max.
10V
25mA
85°C
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ZR431L
Block diagram
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:
Vref
(
ppmIC
)
=
V
dev
x
1000000
V
ref
(
T
1
−
T
2)
The dynamic output impedance, R
z
, is defined as:
R
Z
=
Δ
V
Z
Δ
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
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ZR431L
Electrical characteristics
(at T
amb
= 25°C unless otherwise stated)
Parameter
Reference Voltage
Symbol
2.5% V
ref
1.0% V
ref
V
dev
Min.
1.209
1.228
Typ.
1.24
1.24
4.0
Max.
1.271
1.252
8.0
Unit
V
V
mV
Conditions
I
L
= 10mA (Fig1), V
Z
= V
ref
I
L
= 10mA, V
Z
= V
ref
T
a
= full range (Fig 1)
V
Z
from V
ref
to 10V
I
Z
= 10mA (Fig2)
R1 = 10k, R2 = O/C,
l
L
= 10mA (fig2)
R1 = 10k, R2 = O/C,
I
L
= 10mA T
a
= full
range (Fig2)
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
DC Test circuits
Δ
V
ref
Δ
V
Z
I
ref
I
ref
I
Zmin
I
Zoff
R
Z
0.02
0.5
2.0
mV/V
0.11
0.02
0.4
0.2
A
A
30
10
0.25
100
30
2
A
A
Ω
V
Z
= 10V, V
ref
= 0V
(Fig3)
V
Z
= V
ref
(Fig1), f = 0Hz,
I
L
= 10mA
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
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ZR431L
Typical characteristics
140
Change in reference voltage (mV)
0
-1
-2
-3
-4
-5
-6
-7
-8
-9
0
2
4
6
8
10
Reference Current (nA)
130
120
110
100
90
80
-40
-25
-10
5
20
35
50
65
80
95
110
125
Temperature (°C)
Reference Current v Temperature
Cathode voltage (V)
Change in reference voltage vs Cathode voltage
26
100
Minimum cathode current (µA)
24
Dynamic Impedance (Ω)
10
V
REF
= V
KA
I
K
= 1mA
22
20
1
I
K
= 10mA
18
16
-40
-25
-10
5
20
35
50
65
80
95
110
125
0.1
0.1
1
10
100
Temperature (°C)
Minimum cathode current vs temperature
Frequency (kHz)
Dynamic impedance vs frequency
1.244
350
300
250
200
150
100
50
1.24
1.238
1.236
1.234
1.232
-42
Power dissipation (mW)
Reference voltage (V)
1.242
-25
-10
5
20
35
50
65
80
95
110
125
-40
-25
-10
-5
20
35
50
65
80
95
110
125
Temperature (°C)
Reference voltage vs Temperature
Ambient temperature (°C)
Power dissipation derating
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