AD ADR423BRZ

Ultraprecision, Low Noise, 2.048 V/2.500 V/
3.00 V/5.00 V XFET® Voltage References
ADR420/ADR421/ADR423/ADR425
FEATURES
PIN CONFIGURATION
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/1000 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
TP 1
VIN 2
ADR420/
ADR421/
ADR423/
ADR425
8
TP
7
NIC
VOUT
TOP VIEW
GND 4 (Not to Scale) 5 TRIM
6
NIC = NO INTERNAL CONNECTION
TP = TEST PIN (DO NOT CONNECT)
02432-001
NIC 3
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.
APPLICATIONS
Precision data acquisition systems
High resolution converters
Battery-powered instrumentation
Portable medical instruments
Industrial process control systems
Precision instruments
Optical network control circuits
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 output 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.
ADR42x PRODUCTS
Table 1.
Model
ADR420
ADR421
ADR423
ADR425
Output Voltage, VOUT (V)
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. I
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 ©2001–2011 Analog Devices, Inc. All rights reserved.
ADR420/ADR421/ADR423/ADR425
TABLE OF CONTENTS
Features .............................................................................................. 1 Device Power Dissipation Considerations.............................. 16 Applications....................................................................................... 1 Basic Voltage Reference Connections ..................................... 16 Pin Configuration............................................................................. 1 Noise Performance ..................................................................... 16 General Description ......................................................................... 1 Turn-On Time ............................................................................ 16 ADR42x Products............................................................................. 1 Applications..................................................................................... 17 Revision History ............................................................................... 2 Output Adjustment .................................................................... 17 Specifications..................................................................................... 3 ADR420 Electrical Specifications............................................... 3 Reference for Converters in Optical Network Control
Circuits......................................................................................... 17 ADR421 Electrical Specifications............................................... 4 High Voltage Floating Current Source .................................... 17 ADR423 Electrical Specifications............................................... 5 Kelvin Connections.................................................................... 18 ADR425 Electrical Specifications............................................... 6 Dual-Polarity References........................................................... 18 Absolute Maximum Ratings............................................................ 7 Programmable Current Source ................................................ 19 Thermal Resistance ...................................................................... 7 Programmable DAC Reference Voltage .................................. 19 ESD Caution.................................................................................. 7 Precision Voltage Reference for Data Converters.................. 20 Pin Configurations and Function Descriptions ........................... 8 Precision Boosted Output Regulator ....................................... 20 Typical Performance Characteristics ............................................. 9 Outline Dimensions ....................................................................... 21 Terminology .................................................................................... 15 Ordering Guide .......................................................................... 22 Theory of Operation ...................................................................... 16 REVISION HISTORY
5/11—Rev. H to Rev. I
Added Endnote 1 in Table 2............................................................ 4
Added Endnote 1 in Table 3............................................................ 5
Added Endnote 1 in Table 4............................................................ 6
Added Endnote 1 in Table 5............................................................ 7
Deleted A Negative Precision Reference Without Precision
Resistors Section ............................................................................. 17
Deleted Figure 42; Renumbered Sequentially ............................ 17
Updated Outline Dimensions ....................................................... 21
Changes to Ordering Guide .......................................................... 22
6/07—Rev. G to Rev. H
Changes to Table 2............................................................................ 3
Changes to Table 3............................................................................ 4
Changes to Table 4............................................................................ 5
Changes to Table 5............................................................................ 6
Updated Outline Dimensions ....................................................... 21
Changes to Ordering Guide .......................................................... 22
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
10/01—Rev. 0 to Rev. A
Addition of ADR423 and ADR425 to
ADR420/ADR421...............................................................Universal
5/01—Revision 0: Initial Version
Rev. I | Page 2 of 24
ADR420/ADR421/ADR423/ADR425
SPECIFICATIONS
ADR420 ELECTRICAL SPECIFICATIONS
VIN = 5.0 V to 15.0 V, TA = 25°C, unless otherwise noted.
Table 2.
Parameter
OUTPUT VOLTAGE
A Grade
B Grade
INITIAL ACCURACY 1
A Grade
Symbol
VOUT
Conditions
Typ
Max
Unit
2.045
2.047
2.048
2.048
2.051
2.049
V
V
+3
+0.15
+1
+0.05
mV
%
mV
%
2
1
10
3
10
35
ppm°C
ppm/°C
V
ppm/V
70
ppm/mA
500
600
μA
μA
μV p-p
nV/√Hz
μs
ppm
ppm
dB
mA
VOUTERR
−3
−0.15
−1
−0.05
B Grade
TEMPERATURE COEFFICIENT
A Grade
B Grade
SUPPLY VOLTAGE HEADROOM
LINE REGULATION
VIN − VOUT
∆VOUT/∆VIN
LOAD REGULATION
∆VOUT/∆IL
IL = 0 mA to 10 mA,
−40°C < TA < +125°C
QUIESCENT CURRENT
IIN
VOLTAGE NOISE
VOLTAGE NOISE DENSITY
TURN-ON SETTLING TIME
LONG-TERM STABILITY
OUTPUT VOLTAGE HYSTERESIS
RIPPLE REJECTION RATIO
SHORT CIRCUIT TO GND
eN p-p
eN
tR
∆VOUT
VOUT_HYS
RRR
ISC
No load
−40°C < TA < +125°C
0.1 Hz to 10 Hz
1 kHz
1
Min
TCVOUT
−40°C < TA < +125°C
2
VIN = 5 V to 18 V,
−40°C < TA < +125°C
1000 hours
fIN = 1 kHz
Initial accuracy does not include shift due to solder heat effect.
Rev. I | Page 3 of 24
390
1.75
60
10
50
40
−75
27
ADR420/ADR421/ADR423/ADR425
ADR421 ELECTRICAL SPECIFICATIONS
VIN = 5.0 V to 15.0 V, TA = 25°C, unless otherwise noted.
Table 3.
Parameter
OUTPUT VOLTAGE
A Grade
B Grade
INITIAL ACCURACY 1
A Grade
Symbol
VOUT
Conditions
Typ
Max
Unit
2.497
2.499
2.500
2.500
2.503
2.501
V
V
+3
+0.12
+1
+0.04
mV
%
mV
%
2
1
10
3
10
35
ppm/°C
ppm/°C
V
ppm/V
70
ppm/mA
500
600
μA
μA
μV p-p
nV/√Hz
μs
ppm
ppm
dB
mA
VOUTERR
−3
−0.12
−1
−0.04
B Grade
TEMPERATURE COEFFICIENT
A Grade
B Grade
SUPPLY VOLTAGE HEADROOM
LINE REGULATION
VIN − VOUT
∆VOUT/∆VIN
LOAD REGULATION
∆VOUT/∆IL
QUIESCENT CURRENT
IIN
VOLTAGE NOISE
VOLTAGE NOISE DENSITY
TURN-ON SETTLING TIME
LONG-TERM STABILITY
OUTPUT VOLTAGE HYSTERESIS
RIPPLE REJECTION RATIO
SHORT CIRCUIT TO GND
eN p-p
eN
tR
∆VOUT
VOUT_HYS
RRR
ISC
1
Min
TCVOUT
−40°C < TA < +125°C
2
VIN = 5 V to 18 V,
−40°C < TA < +125°C
IL = 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
1000 hours
fIN = 1 kHz
Initial accuracy does not include shift due to solder heat effect.
Rev. I | Page 4 of 24
390
1.75
80
10
50
40
−75
27
ADR420/ADR421/ADR423/ADR425
ADR423 ELECTRICAL SPECIFICATIONS
VIN = 5.0 V to 15.0 V, TA = 25°C, unless otherwise noted.
Table 4.
Parameter
OUTPUT VOLTAGE
A Grade
B Grade
INITIAL ACCURACY 1
A Grade
Symbol
VOUT
Conditions
Typ
Max
Unit
2.996
2.9985
3.000
3.000
3.004
3.0015
V
V
+4
+0.13
+1.5
+0.04
mV
%
mV
%
2
1
10
3
10
35
ppm/°C
ppm/°C
V
ppm/V
70
ppm/mA
500
600
μA
μA
μV p-p
nV/√Hz
μs
ppm
ppm
dB
mA
VOUTERR
−4
−0.13
−1.5
−0.04
B Grade
TEMPERATURE COEFFICIENT
A Grade
B Grade
SUPPLY VOLTAGE HEADROOM
LINE REGULATION
VIN − VOUT
∆VOUT/∆VIN
LOAD REGULATION
∆VOUT/∆IL
QUIESCENT CURRENT
IIN
VOLTAGE NOISE
VOLTAGE NOISE DENSITY
TURN-ON SETTLING TIME
LONG-TERM STABILITY
OUTPUT VOLTAGE HYSTERESIS
RIPPLE REJECTION RATIO
SHORT CIRCUIT TO GND
eN p-p
eN
tR
∆VOUT
VOUT_HYS
RRR
ISC
1
Min
TCVOUT
−40°C < TA < +125°C
2
VIN = 5 V to 18 V,
−40°C < TA < +125°C
IL = 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
1000 hours
fIN = 1 kHz
Initial accuracy does not include shift due to solder heat effect.
Rev. I | Page 5 of 24
390
2
90
10
50
40
−75
27
ADR420/ADR421/ADR423/ADR425
ADR425 ELECTRICAL SPECIFICATIONS
VIN = 7.0 V to 15.0 V, TA = 25°C, unless otherwise noted.
Table 5.
Parameter
OUTPUT VOLTAGE
A Grade
B Grade
INITIAL ACCURACY 1
A Grade
Symbol
VOUT
Conditions
Typ
Max
Unit
4.994
4.998
5.000
5.000
5.006
5.002
V
V
+6
+0.12
+2
+0.04
mV
%
mV
%
2
1
10
3
10
35
ppm/°C
ppm/°C
V
ppm/V
70
ppm/mA
500
600
μA
μA
μV p-p
nV/√Hz
μs
ppm
ppm
dB
mA
VOUTERR
−6
−0.12
−2
−0.04
B Grade
TEMPERATURE COEFFICIENT
A Grade
B Grade
SUPPLY VOLTAGE HEADROOM
LINE REGULATION
VIN − VO
∆VO/∆VIN
LOAD REGULATION
∆VO/∆IL
QUIESCENT CURRENT
IIN
VOLTAGE NOISE
VOLTAGE NOISE DENSITY
TURN-ON SETTLING TIME
LONG-TERM STABILITY
OUTPUT VOLTAGE HYSTERESIS
RIPPLE REJECTION RATIO
SHORT CIRCUIT TO GND
eN p-p
eN
tR
∆VO
VO_HYS
RRR
ISC
1
Min
TCVOUT
−40°C < TA < +125°C
2
VIN = 7 V to 18 V,
−40°C < TA < +125°C
IL = 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
1000 hours
fIN = 1 kHz
Initial accuracy does not include shift due to solder heat effect.
Rev. I | Page 6 of 24
390
3.4
110
10
50
40
−75
27
ADR420/ADR421/ADR423/ADR425
ABSOLUTE MAXIMUM RATINGS
These ratings apply at 25°C, unless otherwise noted.
THERMAL RESISTANCE
Table 6.
θJA is specified for the worst-case conditions, that is, θJA is
specified for devices soldered in the circuit board for surfacemount packages.
Parameter
Supply Voltage
Output Short-Circuit Duration to GND
Storage Temperature Range
Operating Temperature Range
Junction Temperature Range
Lead Temperature (Soldering, 60 sec)
Rating
18 V
Indefinite
−65°C to +150°C
−40°C to +125°C
−65°C to +150°C
300°C
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
Table 7.
Package Type
8-Lead MSOP (RM)
8-Lead SOIC (R)
ESD CAUTION
Rev. I | Page 7 of 24
θJA
190
130
Unit
°C/W
°C/W
ADR420/ADR421/ADR423/ADR425
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
TP 1
VIN 2
ADR420/
ADR421/
ADR423/
ADR425
8
TP
7
NIC
VOUT
TOP VIEW
GND 4 (Not to Scale) 5 TRIM
NIC = NO INTERNAL CONNECTION
TP = TEST PIN (DO NOT CONNECT)
02432-002
NIC 3
6
Figure 2. 8-Lead SOIC, 8-Lead MSOP Pin Configuration
Table 8. Pin Function Descriptions
Pin No.
1, 8
Mnemonic
TP
2
3, 7
4
5
VIN
NIC
GND
TRIM
6
VOUT
Description
Test Pin. There are actual connections in TP pins, but they are reserved for factory testing purposes. Users should not
connect anything to TP pins; otherwise, the device may not function properly.
Input Voltage.
No Internal Connect. NICs have no internal connections.
Ground Pin = 0 V.
Trim Terminal. It can be used to adjust the output voltage over a ±0.5% range without affecting the temperature
coefficient.
Output Voltage.
Rev. I | Page 8 of 24
ADR420/ADR421/ADR423/ADR425
5.0025
2.0493
5.0023
2.0491
5.0021
2.0489
5.0019
2.0487
5.0017
2.0485
2.0483
5.0015
5.0013
2.0481
5.0011
2.0479
5.0009
2.0477
2.0475
–40
–10
20
50
80
110
125
02432-007
VOUT (V)
2.0495
02432-004
VOUT (V)
TYPICAL PERFORMANCE CHARACTERISTICS
5.0007
5.0005
–40
–10
TEMPERATURE (°C)
20
50
80
110
125
TEMPERATURE (°C)
Figure 3. ADR420 Typical Output Voltage vs. Temperature
Figure 6. ADR425 Typical Output Voltage vs. Temperature
0.55
2.5015
2.5013
0.50
SUPPLY CURRENT (mA)
2.5011
2.5007
2.5005
2.5003
2.5001
2.4999
+25°C
0.40
–40°C
0.35
02432-005
0.30
2.4997
2.4995
–40
+125°C
0.45
–10
20
50
80
110
0.25
125
02432-008
VOUT (V)
2.5009
4
6
8
TEMPERATURE (°C)
10
12
14
15
INPUT VOLTAGE (V)
Figure 4. ADR421 Typical Output Voltage vs. Temperature
Figure 7. ADR420 Supply Current vs. Input Voltage
0.55
3.0010
3.0008
0.50
SUPPLY CURRENT (mA)
3.0006
3.0002
3.0000
2.9998
2.9996
2.9994
+125°C
0.40
+25°C
0.35
–40°C
–10
20
50
80
110
125
TEMPERATURE (°C)
0.25
02432-009
2.9992
2.9990
–40
0.45
0.30
02432-006
VOUT (V)
3.0004
4
6
8
10
12
14
INPUT VOLTAGE (V)
Figure 5. ADR423 Typical Output Voltage vs. Temperature
Figure 8. ADR421 Supply Current vs. Input Voltage
Rev. G | Page 9 of 24
15
ADR420/ADR421/ADR423/ADR425
0.55
70
IL = 0mA TO 5mA
60
LOAD REGULATION (ppm/mA)
0.50
0.40
+25°C
0.35
–40°C
0.30
4
6
8
10
12
14
VIN = 5V
40
30
VIN = 6.5V
20
10
02432-010
0.25
50
0
–40
15
02432-013
SUPPLY CURRENT (mA)
+125°C
0.45
–10
INPUT VOLTAGE (V)
20
50
80
110
125
TEMPERATURE (°C)
Figure 9. ADR423 Supply Current vs. Input Voltage
Figure 12. ADR421 Load Regulation vs. Temperature
0.55
70
IL = 0mA TO 10mA
60
LOAD REGULATION (ppm/mA)
+125°C
0.45
0.40
+25°C
0.35
–40°C
0.30
6
8
10
12
14
VIN = 7V
40
30
VIN = 15V
20
10
02432-011
0.25
50
0
–40
15
02432-014
SUPPLY CURRENT (mA)
0.50
–10
INPUT VOLTAGE (V)
Figure 10. ADR425 Supply Current vs. Input Voltage
35
LOAD REGULATION (ppm/mA)
30
50
40
VIN = 4.5V
20
–10
20
50
110 125
80
110
25
20
15
10
5
0
–40
125
TEMPERATURE (°C)
02432-015
10
02432-012
LOAD REGULATION (ppm/mA)
60
0
–40
80
VIN = 15V
IL = 0mA TO 10mA
IL = 0mA TO 5mA
30
50
Figure 13. ADR423 Load Regulation vs. Temperature
70
VIN = 6V
20
TEMPERATURE (°C)
–10
20
50
80
110 125
TEMPERATURE (°C)
Figure 11. ADR420 Load Regulation vs. Temperature
Figure 14. ADR425 Load Regulation vs. Temperature
Rev. I | Page 10 of 24
ADR420/ADR421/ADR423/ADR425
6
14
VIN = 4.5V TO 15V
VIN = 7.5V TO 15V
12
LINE REGULATION (ppm/V)
4
3
2
1
–10
20
50
80
8
6
4
2
02432-016
0
–40
10
02432-019
LINE REGULATION (ppm/V)
5
0
–40
110 125
–10
TEMPERATURE (°C)
20
50
80
110
125
TEMPERATURE (°C)
Figure 15. ADR420 Line Regulation vs. Temperature
Figure 18. ADR425 Line Regulation vs. Temperature
6
2.5
VIN = 5V TO 15V
4
3
2
0
–40
02432-017
1
–10
20
50
80
110
2.0
–40°C
+85°C
1.0
0.5
0
125
+25°C
1.5
02432-020
DIFFERENTIAL VOLTAGE (V)
LINE REGULATION (ppm/V)
5
0
1
TEMPERATURE (°C)
2
3
4
5
LOAD CURRENT (mA)
Figure 16. ADR421 Line Regulation vs. Temperature
Figure 19. ADR420 Minimum Input/Output Voltage
Differential vs. Load Current
9
2.5
VIN = 5V TO 15V
6
5
4
3
2
1
0
–40
–10
20
50
80
2.0
–40°C
+125°C
1.0
0.5
0
110
TEMPERATURE (°C)
+25°C
1.5
02432-021
DIFFERENTIAL VOLTAGE (V)
7
02432-018
LINE REGULATION (ppm/V)
8
0
1
2
3
4
LOAD CURRENT (mA)
Figure 17. ADR423 Line Regulation vs. Temperature
Figure 20. ADR421 Minimum Input/Output Voltage
Differential vs. Load Current
Rev. I | Page 11 of 24
5
ADR420/ADR421/ADR423/ADR425
2.0
–40°C
1.5
1µV/DIV
+25°C
+125°C
1.0
0
02432-025
0.5
02432-022
DIFFERENTIAL VOLTAGE (V)
2.5
0
1
2
3
4
TIME (1s/DIV)
5
LOAD CURRENT (mA)
Figure 24. ADR421 Typical Noise Voltage 0.1 Hz to 10 Hz
Figure 21. ADR423 Minimum Input/Output Voltage
Differential vs. Load Current
2.0
–40°C
1.5
50µV/DIV
+25°C
+125°C
1.0
0
02432-026
0.5
02432-023
DIFFERENTIAL VOLTAGE (V)
2.5
0
1
2
3
4
TIME (1s/DIV)
5
LOAD CURRENT (mA)
Figure 22. ADR425 Minimum Input/Output Voltage
Differential vs. Load Current
1k
15
10
ADR423
100
ADR420
10
10
40
50
60
70
80
90
100
110
120
130
MORE
–40
–30
–20
–10
0
10
20
30
0
02432-024
5
ADR425
ADR421
02432-027
SAMPLE SIZE – 160
20
–100
–90
–80
–70
–60
–50
NUMBER OF PARTS
25
TEMPERATURE
+25°C
–40°C
+125°C
+25°C
VOLTAGE NOISE DENSITY (nV/ Hz)
30
Figure 25. Typical Noise Voltage 10 Hz to 10 kHz
100
1k
FREQUENCY (Hz)
DEVIATION (ppm)
Figure 26. Voltage Noise Density vs. Frequency
Figure 23. ADR421 Typical Hysteresis
Rev. I | Page 12 of 24
10k
ADR420/ADR421/ADR423/ADR425
CBYPASS = 0µF
CL = 100nF
LINE INTERRUPTION
1mA LOAD
VOUT
VIN
1V/DIV
500mV/DIV
LOAD OFF
VOUT
500mV/DIV
2V/DIV
02432-028
02432-031
LOAD ON
TIME (100µs/DIV)
TIME (100µs/DIV)
Figure 27. ADR421 Line Transient Response, no CBYPASS
CBYPASS = 0.1µF
Figure 30. ADR421 Load Transient Response, CL = 100 nF
CIN = 0.01µF
NO LOAD
LINE INTERRUPTION
VOUT
VIN
2V/DIV
500mV/DIV
VIN
VOUT
500mV/DIV
02432-029
02432-032
2V/DIV
TIME (4µs/DIV)
TIME (100µs/DIV)
Figure 28. ADR421 Line Transient Response, CBYPASS = 0.1 μF
CL = 0µF
Figure 31. ADR421 Turn-Off Response
CIN = 0.01µF
NO LOAD
1mA LOAD
2V/DIV
VOUT
1V/DIV
VOUT
LOAD OFF
2V/DIV
2V/DIV
LOAD ON
02432-030
02432-033
VIN
TIME (4µs/DIV)
TIME (100µs/DIV)
Figure 32. ADR421 Turn-On Response
Figure 29. ADR421 Load Transient Response, no CL
Rev. I | Page 13 of 24
ADR420/ADR421/ADR423/ADR425
50
CL = 0.01µF
NO INPUT CAP
45
VOUT
40
OUTPUT IMPEDANCE (Ω)
2V/DIV
VIN
2V/DIV
35
30
ADR425
25
ADR423
20
ADR421
15
5
0
10
TIME (4µs/DIV)
ADR420
100
1k
10k
02432-037
02432-034
10
100k
FREQUENCY (Hz)
Figure 33. ADR421 Turn-Off Response
Figure 36. Output Impedance vs. Frequency
0
CL = 0.01µF
NO INPUT CAP
–10
2V/DIV
RIPPLE REJECTION (dB)
–20
VOUT
2V/DIV
–30
–40
–50
–60
–70
02432-035
02432-038
–80
VIN
–90
–100
10
TIME (4µs/DIV)
100
1k
10k
100k
FREQUENCY (Hz)
Figure 37. Ripple Rejection vs. Frequency
Figure 34. ADR421 Turn-On Response
CBYPASS = 0.1µF
RL = 500Ω
CL = 0
5V/DIV
VIN
2V/DIV
02432-036
VOUT
TIME (100µs/DIV)
Figure 35. ADR421 Turn-On/Turn-Off Response
Rev. I | Page 14 of 24
1M
ADR420/ADR421/ADR423/ADR425
TERMINOLOGY
Temperature Coefficient
The change of output voltage over the operating temperature
range is normalized by the output voltage at 25°C, and
expressed in ppm/°C as
TCVOUT ( ppm / °C ) =
VOUT (T2 ) − VOUT (T1 )
VOUT ( 25°C ) × (T2 − T1 )
× 10 6
VOUT _ HYS = VOUT ( 25°C ) − VOUT _ TC
VOUT _ HYS ( ppm) =
where:
VOUT (25°C) = VOUT at 25°C.
VOUT (T1) = VOUT at Temperature 1.
VOUT (T2) = VOUT at Temperature 2.
Line Regulation
The change in output voltage due to a specified change in input
voltage. It includes the effects of self-heating. Line regulation is
expressed in either percent per volt, parts per million per volt,
or microvolts per volt change in input voltage.
Load Regulation
The change in output voltage due to a specified change in load
current. It includes the effects of self-heating. Load regulation is
expressed in either microvolts per milliampere, parts per
million per milliampere, or ohms of dc output resistance.
Long-Term Stability
Typical shift of output voltage at 25°C on a sample of parts
subjected to operation life test of 1000 hours at 125°C.
ΔVOUT = VOUT (t 0 ) − VOUT (t 1 )
ΔVOUT ( ppm) =
VOUT (t 0 ) − VOUT (t 1 )
VOUT (t 0 )
Thermal Hysteresis
The change of output voltage after the device is cycled through
temperatures from +25°C to −40°C to +125°C and back to
+25°C. This is a typical value from a sample of parts put
through such a cycle.
× 10 6
where:
VOUT (t0) = VOUT at 25°C at Time 0.
VOUT (t1) = VOUT at 25°C after 1000 hours operation at 125°C.
VOUT ( 25°C ) − VOUT _ TC
VOUT ( 25°C )
× 10 6
where:
VOUT (25°C) = VOUT at 25°C.
VOUT_TC = VOUT at 25 °C after temperature cycle at +25°C to
−40°C to +125°C and back to +25°C.
Input Capacitor
Input capacitors are not required on the ADR42x. There is
no limit for the value of the capacitor used on the input, but a
1 μF to 10 μF capacitor on the input improves transient response
in applications where the supply suddenly changes. An additional 0.1 μF capacitor in parallel also helps to reduce noise
from the supply.
Output Capacitor
The ADR42x do not need output capacitors for stability under
any load condition. An output capacitor, typically 0.1 μF, filters
out any low level noise voltage and does not affect the operation
of the part. On the other hand, the load transient response can
be improved with an additional 1 μF to 10 μF output capacitor
in parallel. A capacitor here acts as a source of stored energy for
sudden increase in load current. The only parameter that
degrades by adding an output capacitor is the turn-on time,
which depends on the size of the selected capacitor.
Rev. I | Page 15 of 24
ADR420/ADR421/ADR423/ADR425
THEORY OF OPERATION
The intrinsic reference voltage is about 0.5 V with a negative
temperature coefficient of about −120 ppm/°C. This slope is
essentially constant to the dielectric constant of silicon and can
be closely compensated by adding a correction term generated
in the same fashion as the proportional-to-temperature (PTAT)
term used to compensate band gap references. The primary
advantage over a band gap reference is that the intrinsic temperature coefficient is approximately 30 times lower (therefore
requiring less correction). This results in much lower noise
because most of the noise of a band gap reference comes from
the temperature compensation circuitry.
DEVICE POWER DISSIPATION CONSIDERATIONS
The ADR42x family of references is guaranteed to deliver load
currents to 10 mA with an input voltage that ranges from 4.5 V
to 18 V. When these devices are used in applications at higher
currents, the following equation should be used to account for
the temperature effects due to power dissipation increases:
TJ = PD × θJA + TA
where:
TJ and TA are the junction temperature and the ambient
temperature, respectively.
PD is the device power dissipation.
θJA is the device package thermal resistance.
BASIC VOLTAGE REFERENCE CONNECTIONS
Voltage references, in general, require a bypass capacitor
connected from VOUT to GND. The circuit in Figure 39
illustrates the basic configuration for the ADR42x family of
references. Other than a 0.1 μF capacitor at the output to help
improve noise suppression, a large output capacitor at the
output is not required for circuit stability.
Figure 38 shows the basic topology of the ADR42x series. The
temperature correction term is provided by a current source
with a value designed to be proportional to absolute temperature. The general equation is
VOUT = G × (ΔVP − R1 × IPTAT)
Each ADR42x device is created by on-chip adjustment of R2
and R3 to achieve the specified reference output.
I1
VIN
I1
ADR420/ADR421/
ADR423/ADR425
IPTAT
VOUT
R2
10µF
+
2
0.1µF
*EXTRA CHANNEL IMPLANT
VOUT = G(∆VP – R1 × IPTAT)
Figure 38. Simplified Schematic
R3
GND
02432-039
R1
NIC 3
4
ADR420/
ADR421/
ADR423/
ADR425
8
TP
7
NIC
OUTPUT
6
TOP VIEW
(Not to Scale) 5 TRIM
0.1µF
NIC = NO INTERNAL CONNECTION
TP = TEST PIN (DO NOT CONNECT)
Figure 39. Basic Voltage Reference Configuration
NOISE PERFORMANCE
The noise generated by ADR42x references is typically less
than 2 μV p-p over the 0.1 Hz to 10 Hz band for the ADR420,
ADR421, and ADR423. Figure 24 shows the 0.1 Hz to 10 Hz
noise of the ADR421, which is only 1.75 μV p-p. The noise
measurement is made with a band-pass filter made of a 2-pole
high-pass filter with a corner frequency at 0.1 Hz and a 2-pole
low-pass filter with a corner frequency at 10 Hz.
TURN-ON TIME
*
∆VP
TP 1
VIN
(1)
where:
G is the gain of the reciprocal of the divider ratio.
ΔVP is the difference in pinch-off voltage between the two JFETs.
IPTAT is the positive temperature coefficient correction current.
(2)
02432-040
The ADR42x series of references uses a reference generation
technique known as XFET (eXtra implanted junction FET).
This technique yields a reference with low supply current, good
thermal hysteresis, and exceptionally low noise. The core of the
XFET reference consists of two junction field-effect transistors
(JFET), one having an extra channel implant to raise its pinchoff voltage. By running the two JFETs at the same drain current,
the difference in pinch-off voltage can be amplified and used to
form a highly stable voltage reference.
At power-up (cold start), the time required for the output
voltage to reach its final value within a specified error band
is defined as the turn-on settling time. Two components typically associated with this are the time for the active circuits to
settle and the time for the thermal gradients on the chip to
stabilize. Figure 31 to Figure 35 show the turn-on settling time
for the ADR421.
Rev. I | Page 16 of 24
ADR420/ADR421/ADR423/ADR425
APPLICATIONS
SOURCE FIBER
OUTPUT ADJUSTMENT
GIMBAL + SENSOR
The ADR42x trim terminal can be used to adjust the output
voltage over a ±0.5% range. This feature allows the system
designer to trim system errors out by setting the reference to
a voltage other than the nominal. This is also helpful if the
part is used in a system at temperature to trim out any error.
Adjustment of the output has a negligible effect on the
temperature performance of the device. To avoid degrading
temperature coefficients, both the trimming potentiometer
and the two resistors need to be low temperature coefficient
types, preferably <100 ppm/°C.
DESTINATION
FIBER
LASER BEAM
MEMS MIRROR
ACTIVATOR
LEFT
AMPL
PREAMP
ACTIVATOR
RIGHT
AMPL
ADR421
CONTROL
ELECTRONICS
ADR421
DAC
ADC
DAC
ADR421
2
GND
4
TRIM 5
Figure 41. All Optical Router Network
HIGH VOLTAGE FLOATING CURRENT SOURCE
R1
470kΩ
R2
RP
10kΩ
10kΩ (ADR420)
15kΩ (ADR421)
The circuit in Figure 42 can be used to generate a floating
current source with minimal self-heating. This particular
configuration can operate on high supply voltages determined
by the breakdown voltage of the N-channel JFET.
Figure 40. Output Trim Adjustment
+VS
SST111
VISHAY
REFERENCE FOR CONVERTERS IN OPTICAL
NETWORK CONTROL CIRCUITS
2
In the high capacity, all optical router network of Figure 41,
arrays of micromirrors direct and route optical signals from
fiber to fiber, without first converting them to electrical form,
which reduces the communication speed. The tiny micromechanical mirrors are positioned so that each is illuminated
by a single wavelength that carries unique information and
can be passed to any desired input and output fiber. The mirrors
are tilted by the dual-axis actuators controlled by precision
analog-to-digital converters (ADCs) and digital-to-analog
converters (DACs) within the system. Due to the microscopic
movement of the mirrors, not only is the precision of the
converters important, but the noise associated with these
controlling converters is extremely critical, because total noise
within the system can be multiplied by the numbers of
converters used. Consequently, the exceptional low noise of the
ADR42x is necessary to maintain the stability of the control
loop for this application.
Rev. I | Page 17 of 24
VIN
ADR420/
ADR421/
ADR423/
ADR425
VOUT 6
OP09
2N3904
GND
4
RL
2.10kΩ
–VS
02432-044
ADR420/
ADR421/
ADR423/
ADR425
DSP
OUTPUT
VOUT = ±0.5%
VOUT 6
02432-041
VIN
02432-042
INPUT
Figure 42. High Voltage Floating Current Source
ADR420/ADR421/ADR423/ADR425
KELVIN CONNECTIONS
DUAL-POLARITY REFERENCES
In many portable instrumentation applications where PC board
cost and area are important considerations, circuit interconnects are often narrow. These narrow lines can cause large
voltage drops if the voltage reference is required to provide load
currents to various functions. In fact, a circuit’s interconnects
can exhibit a typical line resistance of 0.45 mΩ/square (1 oz. Cu,
for example). Force and sense connections, also referred to as
Kelvin connections, offer a convenient method of eliminating
the effects of voltage drops in circuit wires. Load currents flowing through wiring resistance produce an error (VERROR = R × IL)
at the load. However, the Kelvin connection in Figure 43
overcomes the problem by including the wiring resistance
within the forcing loop of the op amp. Because the op amp
senses the load voltage, op amp loop control forces the output to
compensate for the wiring error and to produce the correct
voltage at the load.
Dual-polarity references can easily be made with an op amp and
a pair of resistors. In order not to defeat the accuracy obtained
by the ADR42x, it is imperative to match the resistance tolerance and the temperature coefficient of all components.
VIN
1µF
0.1µF
2
VIN
VOUT 6
U1
ADR425
GND
V+
TRIM 5
U2
OP1177
–5V
R3
5kΩ
02432-046
V–
–10V
Figure 44. +5 V and −5 V Reference Using ADR425
+2.5V
+10V
2
VIN
A1
RLW
VOUT
SENSE
A1 = OP191
VOUT 6
U1
VOUT
FORCE
RL
4
2
VIN
ADR425
GND
4
R1
5.6kΩ
TRIM 5
R2
5.6kΩ
Figure 43. Advantage of Kelvin Connection
–2.5V
V+
U2
OP1177
V–
–10V
02432-047
RLW
02432-045
VOUT 6
GND
R2
10kΩ
+10V
4
VIN
ADR420/
ADR421/
ADR423/
ADR425
+5V
R1
10kΩ
Figure 45. +2.5 V and −2.5 V Reference Using ADR425
Rev. I | Page 18 of 24
ADR420/ADR421/ADR423/ADR425
PROGRAMMABLE CURRENT SOURCE
PROGRAMMABLE DAC REFERENCE VOLTAGE
Together with a digital potentiometer and a Howland current
pump, the ADR425 forms the reference source for a programmable current as
With a multichannel DAC, such as the quad, 12-bit voltage
output AD7398, one of its internal DACs, and an ADR42x
voltage reference can be used as a common programmable
VREFx for the rest of the DACs. The circuit configuration is
shown in Figure 47. The relationship of VREFx to VREF depends
on the digital code and the ratio of R1 and R, and is given by
⎛ R2 A + R2 B ⎞
⎜
⎟
R1
⎝
⎠
IL =
× VW
R2 B
(3)
R2 ⎞
⎛
VREF × ⎜1 +
⎟
R1 ⎠
⎝
VREF x =
D R2 ⎞
⎛
⎜1 + N ×
⎟
2
R1 ⎠
⎝
and
D
2N
× V REF
(4)
where:
D is the decimal equivalent of the input code.
N is the number of bits.
where:
D is the decimal equivalent of input code.
N is the number of bits.
VREF is the applied external reference.
VREFx is the reference voltage for DACs A to D.
C1
10pF
VDD
R1'
50kΩ
2
TRIM
ADR425
4
Table 9. VREFx vs. R1 and R2
VDD
R1, R2
R1 = R2
R1 = R2
R1 = R2
R1 = 3R2
R1 = 3R2
R1 = 3R2
5
U1
GND
R2'
1kΩ
VOUT 6
AD5232
U2
DIGITAL POT
VDD
C2
10pF
V–
A
U2
B W
V+
A2
OP2177
V+
A1
OP2177
V–
VSS
R2B
10Ω
VSS
R1
50kΩ
R2A
1kΩ
VL
LOAD
IL
Digital Code
0000 0000 0000
1000 0000 0000
1111 1111 1111
0000 0000 0000
1000 0000 0000
1111 1111 1111
VREF
2 VREF
1.3 VREF
VREF
4 VREF
1.6 VREF
VREF
02432-048
VIN
(5)
Figure 46. Programmable Current Source
R1' and R2' must be equal to R1 and R2A + R2B, respectively.
Theoretically, R2B can be made as small as needed to achieve
the current needed within A2 output current driving capability.
In the example shown in Figure 46, OP2177 is able to deliver
a maximum of 10 mA. Because the current pump uses both
positive and negative feedback, capacitors C1 and C2 are needed
to ensure that negative feedback prevails and, therefore, avoiding
oscillation. This circuit also allows bidirectional current flow if
the inputs VA and VB of the digital potentiometer are supplied
with the dual-polarity references as previously shown.
VREF A
VOUTA
R1
±0.1%
VREF
DACA
VIN
VREF B
VOUTB
DACB
VREF C
VOUTC
DACC
VREF D
R2
±0.1%
VOUTD
DACD
ADR425
VOB = VREF x (DB)
VOC = VREF x (DC)
VOD = VREF x (DD)
AD7398
Figure 47. Programmable DAC Reference
Rev. I | Page 19 of 24
02432-049
VW =
ADR420/ADR421/ADR423/ADR425
PRECISION BOOSTED OUTPUT REGULATOR
The ADR42x family has a number of features that make it ideal
for use with ADCs and DACs. The exceptionally low noise,
tight temperature coefficient, and high accuracy characteristics
make the ADR42x ideal for low noise applications such as
cellular base station applications.
AD7701 is an example of an ADC that is well suited for the
ADR42x. The ADR421 is used as the precision reference for
the converter in Figure 48. The AD7701 is a 16-bit ADC with
on-chip digital filtering intended for measuring wide dynamic
range and low frequency signals, such as those representing
chemical, physical, or biological processes. It contains a chargebalancing (Σ-Δ) ADC, calibration microcontroller with on-chip
static RAM, clock oscillator, and serial communications port.
+5V
ANALOG
SUPPLY 0.1µF
10µF
VIN
DVDD
SLEEP
VOUT
VREF
ADR420/
ADR421/
ADR423/
ADR425
CS
DATA READY
READ (TRANSMIT)
SCLK
SERIAL CLOCK
SDATA
SERIAL CLOCK
CLKIN
BP/UP
CAL
CALIBRATE
ANALOG
INPUT
ANALOG
GROUND
AIN
AGND
0.1µF
AVSS
–5V
ANALOG
SUPPLY
0.1µF
CLKOUT
SC1
SC2
DGND
0.1µF
DVSS
10µF
02432-050
RANGES
SELECT
5V
2 U1
VIN
VOUT 6
ADR421
RL
25Ω
5
Figure 48. Voltage Reference for 16-Bit ADC AD7701
Rev. I | Page 20 of 24
VOUT
2N7002
+ V+
U2
AD8601
– V–
Figure 49. Precision Boosted Output Regulator
0.1µF
MODE
DRDY
GND
N1
VIN
TRIM
GND
4
AD7701
AVDD
0.1µF
A precision voltage output with boosted current capability
can be realized with the circuit shown in Figure 49. In this
circuit, U2 forces VOUT to be equal to VREF by regulating the turn
on of N1. Therefore, the load current is furnished by VIN. In
this configuration, a 50 mA load is achievable at VIN of 5 V.
Moderate heat is generated on the MOSFET, and higher current
can be achieved by replacing the larger device. In addition, for
a heavy capacitive load with step input, a buffer may be added
at the output to enhance the transient response.
02432-051
PRECISION VOLTAGE REFERENCE FOR DATA
CONVERTERS
ADR420/ADR421/ADR423/ADR425
OUTLINE DIMENSIONS
5.00 (0.1968)
4.80 (0.1890)
8
4.00 (0.1574)
3.80 (0.1497)
5
1
6.20 (0.2441)
5.80 (0.2284)
4
1.27 (0.0500)
BSC
0.25 (0.0098)
0.10 (0.0040)
1.75 (0.0688)
1.35 (0.0532)
0.51 (0.0201)
0.31 (0.0122)
COPLANARITY
0.10
SEATING
PLANE
0.50 (0.0196)
0.25 (0.0099)
45°
8°
0°
0.25 (0.0098)
0.17 (0.0067)
1.27 (0.0500)
0.40 (0.0157)
012407-A
COMPLIANT TO JEDEC STANDARDS MS-012-AA
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
Figure 50. 8-Lead Standard Small Outline Package [SOIC_N]
Narrow Body
(R-8)
Dimensions shown in millimeters and (inches)
3.20
3.00
2.80
3.20
3.00
2.80
8
1
5.15
4.90
4.65
5
4
PIN 1
IDENTIFIER
0.65 BSC
0.95
0.85
0.75
15° MAX
1.10 MAX
0.40
0.25
6°
0°
0.23
0.09
COMPLIANT TO JEDEC STANDARDS MO-187-AA
Figure 51. 8-Lead Mini Small Outline Package [MSOP]
(RM-8)
Dimensions shown in millimeters
Rev. I | Page 21 of 24
0.80
0.55
0.40
10-07-2009-B
0.15
0.05
COPLANARITY
0.10
ADR420/ADR421/ADR423/ADR425
ORDERING GUIDE
Model 1
ADR420ARZ
ADR420ARZ-REEL7
ADR420ARMZ
ADR420ARMZ-REEL7
ADR420BRZ
ADR420BRZ-REEL7
ADR421AR
ADR421ARZ
ADR421ARZ-REEL7
ADR421ARMZ
ADR421ARMZ-REEL7
ADR421BR
ADR421BR-REEL7
ADR421BRZ
ADR421BRZ-REEL7
ADR423ARZ
ADR423ARZ-REEL7
ADR423ARMZ
ADR423ARMZ-REEL7
ADR423BRZ
ADR423BRZ-REEL7
ADR425ARZ
ADR425ARZ-REEL7
ADR425ARMZ
ADR425ARMZ-REEL7
ADR425BR
ADR425BR-REEL7
ADR425BRZ
ADR425BRZ-REEL7
1
Output
Voltage,
VOUT (V)
2.048
2.048
2.048
2.048
2.048
2.048
2.50
2.50
2.50
2.50
2.50
2.50
2.50
2.50
2.50
3.00
3.00
3.00
3.00
3.00
3.00
5.00
5.00
5.00
5.00
5.00
5.00
5.00
5.00
Initial
Accuracy
mV
%
3
0.15
3
0.15
3
0.15
3
0.15
1
0.05
1
0.05
3
0.12
3
0.12
3
0.12
3
0.12
3
0.12
1
0.04
1
0.04
1
0.04
1
0.04
4
0.13
4
0.13
4
0.13
4
0.13
1.5
0.04
1.5
0.04
6
0.12
6
0.12
6
0.12
6
0.12
2
0.04
2
0.04
2
0.04
2
0.04
Temperature
Coefficient
(ppm/°C)
10
10
10
10
3
3
10
10
10
10
10
3
3
3
3
10
10
10
10
3
3
10
10
10
10
3
3
3
3
Temperature
Range
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
Z = RoHS Compliant Part. # denotes RoHS-compliant product may be top or bottom marked.
Rev. I | Page 22 of 24
Package
Description
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead MSOP
8-Lead MSOP
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead MSOP
8-Lead MSOP
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead MSOP
8-Lead MSOP
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead MSOP
8-Lead MSOP
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead SOIC_N
Package
Option
R-8
R-8
RM-8
RM-8
R-8
R-8
R-8
R-8
R-8
RM-8
RM-8
R-8
R-8
R-8
R-8
R-8
R-8
RM-8
RM-8
R-8
R-8
R-8
R-8
RM-8
RM-8
R-8
R-8
R-8
R-8
Branding
L0C
L0C
R06
R06
R0U
R0U
R7A#
R7A#
ADR420/ADR421/ADR423/ADR425
NOTES
Rev. I | Page 23 of 24
ADR420/ADR421/ADR423/ADR425
NOTES
©2001–2011 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D02432-0-5/11(I)
Rev. I | Page 24 of 24