Ultraprecision, Low Noise, 2.048 V/2.500 V/
3.00 V/5.00 V XFET
®
Voltage References
ADR420/ADR421/ADR423/ADR425
FEATURES
Low noise (0.1 Hz to 10 Hz)
ADR420: 1.75 μV p-p
ADR421: 1.75 μV p-p
ADR423: 2.0 μV p-p
ADR425: 3.4 μV p-p
Low temperature coefficient: 3 ppm/°C
Long-term stability: 50 ppm/1,000 hours
Load regulation: 70 ppm/mA
Line regulation: 35 ppm/V
Low hysteresis: 40 ppm typical
Wide operating range
ADR420: 4 V to 18 V
ADR421: 4.5 V to 18 V
ADR423: 5 V to 18 V
ADR425: 7 V to 18 V
Quiescent current: 0.5 mA maximum
High output current: 10 mA
Wide temperature range:
−40°C
to +125°C
PIN CONFIGURATION
TP
1
V
IN 2
NIC
3
6
V
OUT
TOP VIEW
GND
4
(Not to Scale)
5
TRIM
ADR420/
ADR421/
ADR423/
ADR425
8
7
TP
NIC
NIC = NO INTERNAL CONNECTION
TP = TEST PIN (DO NOT CONNECT)
Figure 1. 8-Lead SOIC, 8-Lead MSOP
GENERAL DESCRIPTION
The ADR42x are a series of ultraprecision, second-generation
eXtra implanted junction FET (XFET) voltage references
featuring low noise, high accuracy, and excellent long-term
stability in SOIC and MSOP footprints.
Patented temperature drift curvature correction technique and
XFET technology minimize nonlinearity of the voltage change
with temperature. The XFET architecture offers superior
accuracy and thermal hysteresis to the band gap references. It
also operates at lower power and lower supply headroom than
the buried Zener references.
The superb noise and the stable and accurate characteristics of
the ADR42x make them ideal for precision conversion
applications such as optical networks and medical equipment.
The ADR42x trim terminal can also be used to adjust the out-
put voltage over a ±0.5% range without compromising any
other performance. The ADR42x series voltage references
offer two electrical grades and are specified over the extended
industrial temperature range of −40°C to +125°C. Devices have
8-lead SOIC or 30% smaller, 8-lead MSOP packages.
APPLICATIONS
Precision data acquisition systems
High resolution converters
Battery-powered instrumentation
Portable medical instruments
Industrial process control systems
Precision instruments
Optical network control circuits
ADR42x PRODUCTS
Table 1.
Model
ADR420
ADR421
ADR423
ADR425
Output Voltage (V
O)
2.048
2.50
3.00
5.00
mV
1, 3
1, 3
1.5, 4
2, 6
Initial Accuracy
%
0.05, 0.15
0.04, 0.12
0.04, 0.13
0.04, 0.12
Temperature Coefficient (ppm/°C)
3, 10
3, 10
3, 10
3, 10
Rev. G
Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
© 2005 Analog Devices, Inc. All rights reserved.
02432-001
ADR420/ADR421/ADR423/ADR425
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
Pin Configuration............................................................................. 1
General Description ......................................................................... 1
ADR420 Electrical Specifications................................................... 3
ADR421 Electrical Specifications................................................... 4
ADR423 Electrical Specifications................................................... 5
ADR425 Electrical Specifications................................................... 6
Absolute Maximum Ratings............................................................ 7
ESD Caution.................................................................................. 7
Pin Configuration and Function Descriptions............................. 8
Typical Performance Characteristics ............................................. 9
Parameter Definitions .................................................................... 15
Theory of Operation ...................................................................... 16
Device Power Dissipation Considerations.............................. 16
Basic Voltage Reference Connections...................................... 16
Noise Performance ..................................................................... 16
Turn-On Time ............................................................................ 16
Applications..................................................................................... 17
Output Adjustment .................................................................... 17
Reference for Converters in Optical Network
Control Circuits.......................................................................... 17
A Negative Precision Reference
Without Precision Resistors...................................................... 17
High Voltage Floating Current Source .................................... 18
Kelvin Connections.................................................................... 18
Dual-Polarity References........................................................... 18
Programmable Current Source ................................................ 19
Programmable DAC Reference Voltage .................................. 19
Precision Voltage Reference for Data Converters.................. 20
Precision Boosted Output Regulator ....................................... 20
Outline Dimensions ....................................................................... 21
Ordering Guide .......................................................................... 22
REVISION HISTORY
6/05—Rev. F to Rev. G
Changes to Table 1............................................................................ 1
Changes to Ordering Guide .......................................................... 22
2/05—Rev. E to Rev. F
Updated Format..................................................................Universal
Updated Outline Dimensions ....................................................... 21
Changes to Ordering Guide .......................................................... 22
7/04—Rev. D to Rev. E.
Changes to Ordering Guide ............................................................ 5
3/04—Rev. C to Rev. D.
Changes to Table I ............................................................................ 1
Changes to Ordering Guide ............................................................ 4
Updated Outline Dimensions ....................................................... 16
1/03—Rev. B to Rev. C.
Changed Mini_SOIC to MSOP ........................................Universal
Changes to Ordering Guide .............................................................4
Corrections to Y-axis labels in TPCs 21 and 24 ............................9
Enhancement to Figure 13 ............................................................ 15
Updated Outline Dimensions....................................................... 16
3/02—Rev. A to Rev. B.
Edits to Ordering Guide ...................................................................4
Deletion of Precision Voltage Regulator section........................ 15
Addition of Precision Boosted Output Regulator section ....... 15
Addition of Figure 13..................................................................... 15
Rev. 0 to Rev. A.
Addition of ADR423 and ADR425 to
ADR420/ADR421...............................................................Universal
Rev. G | Page 2 of 24
ADR420/ADR421/ADR423/ADR425
ADR420 ELECTRICAL SPECIFICATIONS
@ V
IN
= 5.0 V to 15.0 V, T
A
= 25°C, unless otherwise noted.
Table 2.
Parameter
Output Voltage, A Grade
Initial Accuracy
Output Voltage, B Grade
Initial Accuracy
Temperature Coefficient A Grade,
Temperature Coefficient, B Grade
Supply Voltage Headroom
Line Regulation
Load Regulation
Quiescent Current
Voltage Noise
Voltage Noise Density
Turn-On Settling Time
Long-Term Stability
Output Voltage Hysteresis
Ripple Rejection Ratio
Short Circuit to GND
Symbol
V
O
V
OERR
V
O
V
OERR
TCV
O
V
IN
– V
O
ΔV
O
/ΔV
IN
ΔV
O
/ΔI
LOAD
I
IN
e
N
p-p
e
N
t
R
ΔV
O
V
O_HYS
RRR
I
SC
−40°C
< TA < +125°C
2
V
IN
= 5 V to 18 V
−40°C
< TA < +125°C
I
LOAD
= 0 mA to 10 mA
−40°C
< TA < +125°C
No load
−40°C
< TA < +125°C
0.1 Hz to 10 Hz
1 kHz
1,000 hours
f
IN
= 10 kHz
390
1.75
60
10
50
40
75
27
10
35
70
500
600
Conditions
Min
2.045
−3
−0.15
2.047
−1
−0.05
Typ
2.048
Max
2.051
+3
+0.15
2.049
+1
+0.05
10
3
Unit
V
mV
%
V
mV
%
ppm°C
ppm/°C
V
ppm/V
ppm/mA
μA
μA
μV p-p
nV/√Hz
μs
ppm
ppm
dB
mA
2.048
2
1
Rev. G | Page 3 of 24
ADR420/ADR421/ADR423/ADR425
ADR421 ELECTRICAL SPECIFICATIONS
@ V
IN
= 5.0 V to 15.0 V, T
A
= 25°C, unless otherwise noted.
Table 3.
Parameter
Output Voltage, A Grade
Initial Accuracy
Output Voltage, B Grade
Initial Accuracy
Temperature Coefficient, A Grade
Temperature Coefficient, B Grade
Supply Voltage Headroom
Line Regulation
Load Regulation
Quiescent Current
Voltage Noise
Voltage Noise Density
Turn-On Settling Time
Long-Term Stability
Output Voltage Hysteresis
Ripple Rejection Ratio
Short Circuit to GND
Symbol
V
O
V
OERR
V
O
V
OERR
TCV
O
V
IN
−
V
O
ΔV
O
/ΔV
IN
ΔV
O
/ΔI
LOAD
I
IN
e
N
p-p
e
N
t
R
ΔV
O
V
O_HYS
RRR
I
SC
−40°C
< TA < +125°C
2
V
IN
= 5 V to 18 V
−40°C
< TA < +125°C
I
LOAD
= 0 mA to 10 mA
−40°C
< TA < +125°C
No load
−40°C
< TA < +125°C
0.1 Hz to 10 Hz
1 kHz
1,000 hours
f
IN
= 10 kHz
390
1.75
80
10
50
40
75
27
10
35
70
500
600
Conditions
Min
2.497
−3
−0.12
2.499
−1
−0.04
Typ
2.500
Max
2.503
+3
+0.12
2.501
+1
+0.04
10
3
Unit
V
mV
%
V
mV
%
ppm/°C
ppm/°C
V
ppm/V
ppm/mA
μA
μA
μV p-p
nV/√Hz
μs
ppm
ppm
dB
mA
2.500
2
1
Rev. G | Page 4 of 24
ADR420/ADR421/ADR423/ADR425
ADR423 ELECTRICAL SPECIFICATIONS
@ V
IN
= 5.0 V to 15.0 V, T
A
= 25°C, unless otherwise noted.
Table 4.
Parameter
Output Voltage, A Grade
Initial Accuracy
Output Voltage, B Grade
Initial Accuracy
Temperature Coefficient, A Grade
Temperature Coefficient, B Grade
Supply Voltage Headroom
Line Regulation
Load Regulation
Quiescent Current
Voltage Noise
Voltage Noise Density
Turn-On Settling Time
Long-Term Stability
Output Voltage Hysteresis
Ripple Rejection Ratio
Short Circuit to GND
Symbol
V
O
V
OERR
V
O
V
OERR
TCV
O
V
IN
−
V
O
ΔV
O
/ΔV
IN
ΔV
O
/ΔI
LOAD
I
IN
e
N
p-p
e
N
t
R
ΔV
O
V
O_HYS
RRR
I
SC
−40°C
< TA < +125°C
2
V
IN
= 5 V to 18 V
−40°C
< TA < +125°C
I
LOAD
= 0 mA to 10 mA
−40°C
< TA < +125°C
No load
−40°C
< TA < +125°C
0.1 Hz to 10 Hz
1 kHz
1,000 hours
f
IN
= 10 kHz
390
2
90
10
50
40
75
27
10
35
70
500
600
Conditions
Min
2.996
−4
−0.13
2.9985
−1.5
−0.04
Typ
3.000
Max
3.004
+4
+0.13
3.0015
+1.5
+0.04
10
3
Unit
V
mV
%
V
mV
%
ppm/°C
ppm/°C
V
ppm/V
ppm/mA
μA
μA
μV p-p
nV/√Hz
μs
ppm
ppm
dB
mA
3.000
2
1
Rev. G | Page 5 of 24
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