Ultralow Noise, LDO XFET Voltage
References with Current Sink and Source
ADR440/ADR441/ADR443/ADR444/ADR445
Rev. E
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Fax: 781.461.3113 ©2005–2010 Analog Devices, Inc. All rights reserved.
FEATURES
Ultralow noise (0.1 Hz to 10 Hz)
ADR440: 1 μV p-p
ADR441: 1.2 μV p-p
ADR443: 1.4 μV p-p
ADR444: 1.8 μV p-p
ADR445: 2.25 μV p-p
Superb temperature coefficient
A grade: 10 ppm/°C
B grade: 3 ppm/°C
Low dropout operation: 500 mV
Input range: (VOUT + 500 mV) to 18 V
High output source and sink current
+10 mA and −5 mA, respectively
Wide temperature range: −40°C to +125°C
APPLICATIONS
Precision data acquisition systems
High resolution data converters
Battery-powered instrumentation
Portable medical instruments
Industrial process control systems
Precision instruments
Optical control circuits
PIN CONFIGURATIONS
NOTES
1. NC = NO CONNE CT
2. TP = TEST PIN (DO NOT CO NNECT)
TP
1
V
IN 2
NC
3
GND
4
TP
8
NC
7
V
OUT
6
TRIM
5
ADR440/
ADR441/
ADR443/
ADR444/
ADR445
TOP V IEW
(Not to Scale)
05428-001
Figure 1. 8-Lead SOIC_N (R-Suffix)
05428-002
TP
1
V
IN 2
NC
3
GND
4
TP
8
NC
7
V
OUT
6
TRIM
5
ADR440/
ADR441/
ADR443/
ADR444/
ADR445
TOP V IEW
(No t to S cal e)
NOTES
1. NC = NO CONNE CT
2. TP = T EST P IN (DO NOT CONNECT)
Figure 2. 8-Lead MSOP (RM-Suffix)
GENERAL DESCRIPTION
The ADR44x series is a family of XFET® voltage references
featuring ultralow noise, high accuracy, and low temperature
drift performance. Using Analog Devices, Inc., patented
temperature drift curvature correction and XFET (eXtra
implanted junction FET) technology, voltage change vs.
temperature nonlinearity in the ADR44x is greatly minimized.
The XFET references offer better noise performance than
buried Zener references, and XFET references operate off
low supply voltage headroom (0.5 V). This combination of
features makes the ADR44x family ideally suited for precision
signal conversion applications in high-end data acquisition
systems, optical networks, and medical applications.
The ADR44x family has the capability to source up to 10 mA of
output current and sink up to −5 mA. It also comes with a trim
terminal to adjust the output voltage over a 0.5% range without
compromising performance.
Offered in two electrical grades, the ADR44x family is avail-
able in 8-lead MSOP and narrow SOIC packages. All versions
are specified over the extended industrial temperature range of
−40°C to +125°C.
Table 1. Selection Guide
Model
Output
Voltage
(V)
Initial
Accuracy
(mV)
Temperature
Coefficient
(ppm/°C)
ADR440A 2.048 ±3 10
ADR440B 2.048 ±1 3
ADR441A 2.500 ±3 10
ADR441B 2.500 ±1 3
ADR443A 3.000 ±4 10
ADR443B 3.000 ±1.2 3
ADR444A 4.096 ±5 10
ADR444B 4.096 ±1.6 3
ADR445A 5.000 ±6 10
ADR445B 5.000 ±2 3
ADR440/ADR441/ADR443/ADR444/ADR445
Rev. E | Page 2 of 20
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
Pin Configurations ........................................................................... 1
General Description......................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
ADR440 Electrical Characteristics............................................. 3
ADR441 Electrical Characteristics............................................. 4
ADR443 Electrical Characteristics............................................. 5
ADR444 Electrical Characteristics............................................. 6
ADR445 Electrical Characteristics............................................. 7
Absolute Maximum Ratings............................................................ 8
Thermal Resistance ...................................................................... 8
ESD Caution.................................................................................. 8
Typical Performance Characteristics ............................................. 9
Theory of Operation ...................................................................... 14
Power Dissipation Considerations........................................... 14
Basic Voltage Reference Connections ..................................... 14
Noise Performance ..................................................................... 14
Turn-On Time ............................................................................ 14
Applications Information.............................................................. 15
Output Adjustment .................................................................... 15
Bipolar Outputs .......................................................................... 15
Programmable Voltage Source ................................................. 15
Programmable Current Source ................................................ 16
High Voltage Floating Current Source.................................... 16
Precision Output Regulator (Boosted Reference)................. 16
Outline Dimensions ....................................................................... 17
Ordering Guide .......................................................................... 18
REVISION HISTORY
11/10—Rev. D to Rev. E
Deleted Negative Reference Section............................................. 15
Deleted Figure 37; Renumbered Sequentially ............................ 15
3/10—Rev. C to Rev. D
Changes to Figure 37...................................................................... 15
Updated Outline Dimensions....................................................... 18
3/08—Rev. B to Rev. C
Changes to Table 8............................................................................ 8
Change to Figure 11 ....................................................................... 10
Changes to Figure 36...................................................................... 15
Changes to Figure 39...................................................................... 16
Changes to Figure 41...................................................................... 17
Updated Outline Dimensions....................................................... 18
8/07—Rev. A to Rev. B
Change to Table 2, Ripple Rejection Ratio Specification ............ 3
Change to Table 3, Ripple Rejection Ratio Specification ............ 4
Change to Table 4, Ripple Rejection Ratio Specification ............ 5
Change to Table 5, Ripple Rejection Ratio Specification ............ 6
Change to Table 6, Ripple Rejection Ratio Specification ............ 7
9/06—Rev. 0 to Rev. A
Updated Format..................................................................Universal
Changes to Features ..........................................................................1
Changes to Pin Configurations .......................................................1
Changes to Specifications Section...................................................3
Changes to Figure 4 and Figure 5....................................................9
Inserted Figure 6 and Figure 7.........................................................9
Changes to Figure 15...................................................................... 11
Changes to Power Dissipation Considerations Section ............ 14
Changes to Figure 35 and Figure 36............................................. 15
Changes to Figure 38 and Table 9................................................. 16
Updated Outline Dimensions....................................................... 18
Changes to Ordering Guide.......................................................... 19
10/05—Revision 0: Initial Version
ADR440/ADR441/ADR443/ADR444/ADR445
Rev. E | Page 3 of 20
SPECIFICATIONS
ADR440 ELECTRICAL CHARACTERISTICS
VIN = 3 V to 18 V, TA = 25°C, CIN = COUT = 0.1 µF, unless otherwise noted.
Table 2.
Parameter Symbol Conditions Min Typ Max Unit
OUTPUT VOLTAGE VO
A Grade 2.045 2.048 2.051 V
B Grade 2.047 2.048 2.049 V
INITIAL ACCURACY VOERR
A Grade 3 mV
0.15 %
B Grade 1 mV
0.05 %
TEMPERATURE DRIFT TCVO
A Grade −40°C < TA < +125°C 2 10 ppm/°C
B Grade −40°C < TA < +125°C 1 3 ppm/°C
LINE REGULATION ΔVO/ΔVIN −40°C < TA < +125°C −20 +10 +20 ppm/V
LOAD REGULATION ΔVO/ΔILOAD ILOAD = 0 mA to 10 mA, VIN = 3.5 V,
−40°C < TA < +125°C −50 +50 ppm/mA
ΔVO/ΔILOAD ILOAD = 0 mA to −5 mA, VIN = 3.5 V,
−40°C < TA < +125°C −50 +50 ppm/mA
QUIESCENT CURRENT IIN No load, −40°C < TA < +125°C 3 3.75 mA
VOLTAGE NOISE eN p-p 0.1 Hz to 10 Hz 1 μV p-p
VOLTAGE NOISE DENSITY eN 1 kHz 45 nV/√Hz
TURN-ON SETTLING TIME tR 10 μs
LONG-TERM STABILITY1 V
O 1000 hours 50 ppm
OUTPUT VOLTAGE HYSTERESIS VO_HYS 70 ppm
RIPPLE REJECTION RATIO RRR fIN = 1 kHz −80 dB
SHORT CIRCUIT TO GND ISC 27 mA
SUPPLY VOLTAGE OPERATING RANGE VIN 3 18 V
SUPPLY VOLTAGE HEADROOM VIN − VO 500 mV
1 The long-term stability specification is noncumulative. The drift in the subsequent 1000-hour period is significantly lower than in the first 1000-hour period.
ADR440/ADR441/ADR443/ADR444/ADR445
Rev. E | Page 4 of 20
ADR441 ELECTRICAL CHARACTERISTICS
VIN = 3 V to 18 V, TA = 25°C, CIN = COUT = 0.1 µF, unless otherwise noted.
Table 3.
Parameter Symbol Conditions Min Typ Max Unit
OUTPUT VOLTAGE VO
A Grade 2.497 2.500 2.503 V
B Grade 2.499 2.500 2.501 V
INITIAL ACCURACY VOERR
A Grade 3 mV
0.12 %
B Grade 1 mV
0.04 %
TEMPERATURE DRIFT TCVO
A Grade −40°C < TA < +125°C 2 10 ppm/°C
B Grade −40°C < TA < +125°C 1 3 ppm/°C
LINE REGULATION ΔVO/ΔVIN −40°C < TA < +125°C 10 20 ppm/V
LOAD REGULATION ΔVO/ΔILOAD ILOAD = 0 mA to 10 mA, VIN = 4 V,
−40°C < TA < +125°C −50 +50 ppm/mA
ΔVO/ΔILOAD ILOAD = 0 mA to −5 mA, VIN = 4 V,
−40°C < TA < +125°C −50 +50 ppm/mA
QUIESCENT CURRENT IIN No load, −40°C < TA < +125°C 3 3.75 mA
VOLTAGE NOISE eN p-p 0.1 Hz to 10 Hz 1.2 μV p-p
VOLTAGE NOISE DENSITY eN 1 kHz 48 nV/√Hz
TURN-ON SETTLING TIME tR 10 μs
LONG-TERM STABILITY1 V
O 1000 hours 50 ppm
OUTPUT VOLTAGE HYSTERESIS VO_HYS 70 ppm
RIPPLE REJECTION RATIO RRR fIN = 1 kHz −80 dB
SHORT CIRCUIT TO GND ISC 27 mA
SUPPLY VOLTAGE OPERATING RANGE VIN 3 18 V
SUPPLY VOLTAGE HEADROOM VIN − VO 500 mV
1 The long-term stability specification is noncumulative. The drift in subsequent 1000-hour period is significantly lower than in the first 1000-hour period.
ADR440/ADR441/ADR443/ADR444/ADR445
Rev. E | Page 5 of 20
ADR443 ELECTRICAL CHARACTERISTICS
VIN = 3.5 V to 18 V, TA = 25°C, CIN = COUT = 0.1 µF, unless otherwise noted.
Table 4.
Parameter Symbol Conditions Min Typ Max Unit
OUTPUT VOLTAGE VO
A Grade 2.996 3.000 3.004 V
B Grade 2.9988 3.000 3.0012 V
INITIAL ACCURACY VOERR
A Grade 4 mV
0.13 %
B Grade 1.2 mV
0.04 %
TEMPERATURE DRIFT TCVO
A Grade −40°C < TA < +125°C 2 10 ppm/°C
B Grade −40°C < TA < +125°C 1 3 ppm/°C
LINE REGULATION ΔVO/ΔVIN −40°C < TA < +125°C 10 20 ppm/V
LOAD REGULATION ΔVO/ΔILOAD ILOAD = 0 mA to 10 mA, VIN = 5 V,
−40°C < TA < +125°C −50 +50 ppm/mA
ΔVO/ΔILOAD ILOAD = 0 mA to −5 mA, VIN = 5 V,
−40°C < TA < +125°C −50 +50 ppm/mA
QUIESCENT CURRENT IIN No load, −40°C < TA < +125°C 3 3.75 mA
VOLTAGE NOISE eN p-p 0.1 Hz to 10 Hz 1.4 μV p-p
VOLTAGE NOISE DENSITY eN 1 kHz 57.6 nV/√Hz
TURN-ON SETTLING TIME tR 10 μs
LONG-TERM STABILITY1 V
O 1000 hours 50 ppm
OUTPUT VOLTAGE HYSTERESIS VO_HYS 70 ppm
RIPPLE REJECTION RATIO RRR fIN = 1 kHz −80 dB
SHORT CIRCUIT TO GND ISC 27 mA
SUPPLY VOLTAGE OPERATING RANGE VIN 3.5 18 V
SUPPLY VOLTAGE HEADROOM VIN − VO 500 mV
1 The long-term stability specification is noncumulative. The drift in the subsequent 1000-hour period is significantly lower than in the first 1000-hour period.
ADR440/ADR441/ADR443/ADR444/ADR445
Rev. E | Page 6 of 20
ADR444 ELECTRICAL CHARACTERISTICS
VIN = 4.6 V to 18 V, TA = 25°C, CIN = COUT = 0.1 µF, unless otherwise noted.
Table 5.
Parameter Symbol Conditions Min Typ Max Unit
OUTPUT VOLTAGE VO
A Grade 4.091 4.096 4.101 V
B Grade 4.0944 4.096 4.0976 V
INITIAL ACCURACY VOERR
A Grade 5 mV
0.13 %
B Grade 1.6 mV
0.04 %
TEMPERATURE DRIFT TCVO
A Grade −40°C < TA < +125°C 2 10 ppm/°C
B Grade −40°C < TA < +125°C 1 3 ppm/°C
LINE REGULATION ΔVO/ΔVIN −40°C < TA < +125°C 10 20 ppm/V
LOAD REGULATION ΔVO/ΔILOAD ILOAD = 0 mA to 10 mA, VIN = 5.5 V,
−40°C < TA < +125°C −50 +50 ppm/mA
ΔVO/ΔILOAD ILOAD = 0 mA to −5 mA, VIN = 5.5 V,
−40°C < TA < +125°C −50 +50 ppm/mA
QUIESCENT CURRENT IIN No load, −40°C < TA < +125°C 3 3.75 mA
VOLTAGE NOISE eN p-p 0.1 Hz to 10 Hz 1.8 μV p-p
VOLTAGE NOISE DENSITY eN 1 kHz 78.6 nV/√Hz
TURN-ON SETTLING TIME tR 10 μs
LONG-TERM STABILITY1 V
O 1000 hours 50 ppm
OUTPUT VOLTAGE HYSTERESIS VO_HYS 70 ppm
RIPPLE REJECTION RATIO RRR fIN = 1 kHz −80 dB
SHORT CIRCUIT TO GND ISC 27 mA
SUPPLY VOLTAGE OPERATING RANGE VIN 4.6 18 V
SUPPLY VOLTAGE HEADROOM VIN − VO 500 mV
1 The long-term stability specification is noncumulative. The drift in the subsequent 1000-hour period is significantly lower than in the first 1000-hour period.
ADR440/ADR441/ADR443/ADR444/ADR445
Rev. E | Page 7 of 20
ADR445 ELECTRICAL CHARACTERISTICS
VIN = 5.5 V to 18 V, TA = 25°C, CIN = COUT = 0.1 µF, unless otherwise noted.
Table 6.
Parameter Symbol Conditions Min Typ Max Unit
OUTPUT VOLTAGE VO
A Grade 4.994 5.000 5.006 V
B Grade 4.998 5.000 5.002 V
INITIAL ACCURACY VOERR
A Grade 6 mV
0.12 %
B Grade 2 mV
0.04 %
TEMPERATURE DRIFT TCVO
A Grade −40°C < TA < +125°C 2 10 ppm/°C
B Grade −40°C < TA < +125°C 1 3 ppm/°C
LINE REGULATION ΔVO/ΔVIN −40°C < TA < +125°C 10 20 ppm/V
LOAD REGULATION ΔVO/ΔILOAD ILOAD = 0 mA to 10 mA, VIN = 6.5 V,
−40°C < TA < +125°C −50 +50 ppm/mA
ΔVO/ΔILOAD ILOAD = 0 mA to −5 mA, VIN = 6.5 V,
−40°C < TA < +125°C −50 +50 ppm/mA
QUIESCENT CURRENT IIN No load, −40°C < TA < +125°C 3 3.75 mA
VOLTAGE NOISE eN p-p 0.1 Hz to 10 Hz 2.25 μV p-p
VOLTAGE NOISE DENSITY eN 1 kHz 90 nV/√Hz
TURN-ON SETTLING TIME tR 10 μs
LONG-TERM STABILITY1 V
O 1000 hours 50 ppm
OUTPUT VOLTAGE HYSTERESIS VO_HYS 70 ppm
RIPPLE REJECTION RATIO RRR fIN = 1 kHz –80 dB
SHORT CIRCUIT TO GND ISC 27 mA
SUPPLY VOLTAGE OPERATING RANGE VIN 5.5 18 V
SUPPLY VOLTAGE HEADROOM VIN − VO 500 mV
1 The long-term stability specification is noncumulative. The drift in the subsequent 1000-hour period is significantly lower than in the first 1000-hour period.
ADR440/ADR441/ADR443/ADR444/ADR445
Rev. E | Page 8 of 20
ABSOLUTE MAXIMUM RATINGS
TA = 25°C, unless otherwise noted.
Table 7.
Parameter Rating
Supply Voltage 20 V
Output Short-Circuit Duration to GND Indefinite
Storage Temperature Range −65°C to +125°C
Operating Temperature Range −40°C to +125°C
Junction Temperature Range −65°C to +150°C
Lead Temperature, Soldering (60 sec) 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.
THERMAL RESISTANCE
θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.
Table 8. Thermal Resistance
Package Type θJA θ
JC Unit
8-Lead SOIC (R-Suffix) 130 43 °C/W
8-Lead MSOP (RM-Suffix) 132.5 43.9 °C/W
ESD CAUTION
ADR440/ADR441/ADR443/ADR444/ADR445
Rev. E | Page 9 of 20
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 7 V, TA = 25°C, CIN = COUT = 0.1 µF, unless otherwise noted.
2.051
2.050
2.049
2.048
2.047
2.046
2.045
–40 –20 0 20 100806040 120
TEMPERATURE (° C)
OUTPUT VOLTAGE (V)
05428-042
Figure 3. ADR440 Output Voltage vs. Temperature
TEM P ERATURE (°C)
OUT P UT VOLTAGE (V)
2.5020
2.5015
2.5005
2.5010
2.5000
2.4995
2.4990
–40 5–10–25 503520 110958065 125
05428-003
Figure 4. ADR441 Output Voltage vs. Temperature
TEM P ERATURE (°C)
OUT P UT VOLTAGE (V)
3.0020
3.0015
3.0000
3.0005
3.0010
2.9995
2.9985
2.9990
2.9980
–40 5–10–25 503520 110958065 125
DEVI CE 1
DEVI CE 2
DEVI CE 3
05428-004
Figure 5. ADR443 Output Voltage vs. Temperature
TEM P ERATURE (°C)
OUT P UT VOLTAGE (V)
4.0980
4.0975
4.0960
4.0965
4.0970
4.0955
4.0945
4.0950
4.0940
–40 5–10–25 503520 110958065 125
05428-005
DEVICE 1
DEVI CE 2
DEVICE 3
Figure 6. ADR444 Output Voltage vs. Temperature
5.006
5.004
5.002
5.000
4.998
4.996
4.994
–40 –20 0 20 100806040 120
TEMPERATURE (° C)
OUTPUT VOLTAGE (V)
05428-043
Figure 7. ADR445 Output Voltage vs. Temperature
INPUT VOLTAGE (V)
SUPP LY CURRENT (mA)
4.0
3.5
3.0
2.5
2.0 46 10811412 18
05428-006
6
+125°C
–40°C
+25°C
Figure 8. ADR441 Supply Current vs. Input Voltage
ADR440/ADR441/ADR443/ADR444/ADR445
Rev. E | Page 10 of 20
TEM P ERATURE (°C)
SUPP LY CURRENT (mA)
4.0
3.5
3.0
2.5
2.0
–40 5–10–25 503520 110958065 125
05428-007
Figure 9. ADR441 Supply Current vs. Temperature
INPUT VOLTAGE (V)
SUPP LY CURRENT (mA)
3.5
3.4
3.2
3.3
3.0
2.9
2.8
2.7
2.6
3.1
2.55.3 9.37.3 13.311.3 17.315.3 19.3
05428-008
–40°C
+125°C
+25°C
Figure 10. ADR445 Supply Current vs. Input Voltage
TEM P ERATURE (°C)
SUPP LY CURRENT (mA)
3.25
3.15
3.05
2.95
2.85
2.75
–40 5–10–25 503520 110958065 125
05428-009
Figure 11. ADR445 Supply Current vs. Temperature
TEM P ERATURE (°C)
LINE REGUL
A
TION (ppm/V)
10
8
6
2
4
0
–40 5–10–25 503520 110958065 125
05428-010
Figure 12. ADR441 Line Regulation vs. Temperature
TEM P ERATURE (°C)
LOAD REGUL
A
TION (ppm/mA)
60
55
50
40
35
45
30
–40 5–10–25 503520 110958065 125
05428-011
V
IN
= 18V
I
LOAD
= 0mA TO 10mA
V
IN
= 6V
Figure 13. ADR441 Load Regulation vs. Temperature
TEMPERATURE (°C)
LI NE REGUL ATION (p pm/ V)
7
6
5
4
1
2
3
0
–40 5–10–25 503520 110958065 125
05428-012
Figure 14. ADR445 Line Regulation vs. Temperature
ADR440/ADR441/ADR443/ADR444/ADR445
Rev. E | Page 11 of 20
TEM P ERATURE (°C)
LOAD REGUL
A
TION (ppm/mA)
50
40
30
20
–30
–40
–20
–10
0
10
–50
–40 5–10–25 503520 110958065 125
05428-013
I
LOAD
= 0mA TO +10mA
I
LOAD
= 0mA TO –5mA
V
IN
= 6V
Figure 15. ADR445 Load Regulation vs. Temperature
+125°C
–40°C
+25°C
LOAD CURRENT (mA)
DIFFERENTI
A
L VOLTAGE ( V )
0.7
0.6
0.5
0.3
0.2
0.1
0.4
0
–10 –5 0 5 10
05428-014
Figure 16. ADR441 Minimum Input/Output
Differential Voltage vs. Load Current
TEM P ERATURE (°C)
MI NIMUM HEADROOM (V)
0.5
0.4
0.3
0.2
0.1
0
–40 5–10–25 503520 110958065 125
05428-015
NO LO AD
Figure 17. ADR441 Minimum Headroom vs. Temperature
LOAD CURRENT (mA)
DIFFERENTI
A
L VOLTAGE ( V )
1.0
0.9
0.8
0.7
0.6
0.5
0.3
0.2
0.1
0.4
0–5 0 5 10
05428-016
+125°C
–40°C
+25°C
Figure 18. ADR445 Minimum Input/Output
Differential Voltage vs. Load Current
TEM P ERATURE (°C)
MI NIMUM HEADROOM (V)
0.5
0.4
0.3
0.2
0.1
0
–40 5–10–25 503520 110958065 125
05428-017
NO LO AD
Figure 19. ADR445 Minimum Headroom vs. Temperature
05428-018
V
OUT
= 1V/DIV
V
IN
= 5V/DIV
TIME = 10µs/DIV
C
IN
= C
OUT
= 0.1µF
Figure 20. ADR441 Turn-On Response
ADR440/ADR441/ADR443/ADR444/ADR445
Rev. E | Page 12 of 20
05428-019
V
OUT
= 1V/DIV
V
IN
= 5V/DIV
TI ME = 200µs/ DIV
C
IN
= C
OUT
= 0. 1µF
Figure 21. ADR441 Turn-Off Response
05428-020
VOUT = 1V/DIV
VIN = 5V/DIV
CIN = 0.1µF
COUT = 10µF
TI ME = 200µs/ DIV
Figure 22. ADR441 Turn-On Response
05428-021
2V/DIV
4V
2mV/DIV
C
IN
= 0. 1µF
C
OUT
= 10µF
TIME = 100µ s /DI V
Figure 23. ADR441 Line Transient Response
05428-023
LOAD OF F LO AD ON
5mV/DIV
C
IN
= 0. 1µF
C
OUT
= 10µF
TI ME = 200µs/ DIV
Figure 24. ADR441 Load Transient Response
05428-022
LOAD OF F LOAD ON
5mV/DIV
C
IN
= C
OUT
= 0. 1µF
TIME = 2 00µ s/DIV
Figure 25. ADR441 Load Transient Response
05428-024
CH 1 p- p
1.18µV
1µV/DIV
TIME = 1s/DIV
Figure 26. ADR441 0.1 Hz to 10.0 Hz Voltage Noise
ADR440/ADR441/ADR443/ADR444/ADR445
Rev. E | Page 13 of 20
05428-025
50µV/DIV
TIME = 1s/DIV
CH 1 p- p
49µV
Figure 27. ADR441 10 Hz to 10 kHz Voltage Noise
05428-026
CH 1 p- p
2.24µV
1µV/DIV
TIME = 1s/DIV
Figure 28. ADR445 0.1 Hz to 10.0 Hz Voltage Noise
05428-027
50µV/DIV
TIME = 1s/DIV
CH 1 p- p
66µV
Figure 29. ADR445 10 Hz to 10 kHz Voltage Noise
DEVIATI ON (p pm)
NUMBER OF PARTS
16
0
05428-028
14
12
10
8
6
4
2
–130
–150
–110
–90
–70
–50
–10
–30
10
30
50
70
110
90
130
150
Figure 30. ADR441 Typical Output Voltage Hysteresis
FRE QUENC Y (Hz)
OUT P UT IM P E DANCE ( Ω)
100k10k1k10010
05428-029
ADR445
ADR443
ADR441
10
9
8
7
5
6
4
3
2
1
0
Figure 31. Output Impedance vs. Frequency
FRE QUENC Y (Hz)
RIPP LE REJECTION R
A
TIO (dB)
100k 1M10k1k100
05428-030
–10
0
–20
–30
–40
–50
–60
–70
–80
–90
–100
Figure 32. Ripple Rejection Ratio vs. Frequency
ADR440/ADR441/ADR443/ADR444/ADR445
Rev. E | Page 14 of 20
THEORY OF OPERATION
The ADR44x series of references uses a new reference generation
technique known as XFET (eXtra implanted junction FET).
This technique yields a reference with low dropout, good
thermal hysteresis, and exceptionally low noise. The core of the
XFET reference consists of two junction field-effect transistors
(JFETs), one of which has an extra channel implant to raise its
pinch-off 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.
The intrinsic reference voltage is around 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 it can
be closely compensated for by adding a correction term generated
in the same fashion as the proportional-to-absolute temperature
(PTAT) term used to compensate band gap references. The
advantage of an XFET reference is its correction term, which is
approximately 20 times lower and requires less correction than
that of a band gap reference. Because most of the noise of a band
gap reference comes from the temperature compensation
circuitry, the XFET results in much lower noise.
Figure 33 shows the basic topology of the ADR44x series. The
temperature correction term is provided by a current source with
a value designed to be proportional to the absolute temperature.
The general equation is
VOUT = G (VP − R1 × IPTAT) (1)
where:
G is the gain of the reciprocal of the divider ratio.
∆VP is the difference in pinch-off voltage between the two JFETs.
IPTAT is the positive temperature coefficient correction current.
ADR44x devices are created by on-chip adjustment of R2
and R3 to achieve the different voltage options at the
reference output.
I
PTAT
I
1
*
I
1
*EXT RA CHANNEL IM PLANT
V
OUT
= G (∆V
P
– R1 × I
PTAT
)
R2
V
IN
V
OUT
GND
R3
R1
∆V
P
05428-033
ADR44x
Figure 33. Simplified Schematic Device
POWER DISSIPATION CONSIDERATIONS
The ADR44x family of references is guaranteed to deliver load
currents to 10 mA with an input voltage that ranges from 3 V to
18 V. When these devices are used in applications at higher
currents, use the following equation to account for the
temperature effects of increases in power dissipation:
TJ = PD × θJA + TA (2)
where:
TJ and TA are the junction and ambient temperatures,
respectively.
PD is the device power dissipation.
θJA is the device package thermal resistance.
BASIC VOLTAGE REFERENCE CONNECTIONS
The ADR44x family requires a 0.1 µF capacitor on the input
and the output for stability. Although not required for operation,
a 10 µF capacitor at the input can help with line voltage
transient performance.
NOTES
1. NC = NO CONNECT
2. TP = T EST P IN (DO NOT CONNECT)
05428-034
6
V
OUT
0.1µF
+
V
IN
10µF 0.1µF
TP
1
NC
3
4
TP
8
NC
7
TRIM
5
ADR440/
ADR441/
ADR443/
ADR444/
ADR445
TOP VI EW
(Not to Scale)
2
GND
Figure 34. Basic Voltage Reference Configuration
NOISE PERFORMANCE
The noise generated by the ADR44x family of references is
typically less than 1.4 µV p-p over the 0.1 Hz to 10.0 Hz band
for ADR440, ADR441, and ADR443. Figure 26 shows the 0.1 Hz
to 10 Hz noise of the ADR441, which is only 1.2 µV p-p. The
noise measurement is made with a band-pass filter composed 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 10.0 Hz.
TURN-ON TIME
Upon application of power (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 compo-
nents normally 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 20 and Figure 21 show the turn-on and
turn-off settling times for the ADR441.
ADR440/ADR441/ADR443/ADR444/ADR445
Rev. E | Page 15 of 20
APPLICATIONS INFORMATION
OUTPUT ADJUSTMENT
The ADR44x family features a TRIM pin that allows the user to
adjust the output voltage of the part over a limited range. This
allows errors from the reference and overall system errors to be
trimmed out by connecting a potentiometer between the output
and the ground, with the wiper connected to the TRIM pin.
Figure 35 shows the optimal trim configuration. R1 allows fine
adjustment of the output and is not always required. RP should
be sufficiently large so that the maximum output current from
the ADR44x is not exceeded.
TRIM
V
IN
V
O
= ±0.5%
0.1µF
0.1µF
GND R2
1kΩ
R
P
10kΩ
05428-035
V
OUT 6
2
5
4
R1
100kΩ
ADR440/
ADR441/
ADR443/
ADR444/
ADR445
Figure 35. ADR44x Trim Function
Using the trim function has a negligible effect on the temperature
performance of the ADR44x. However, all resistors need to be
low temperature coefficient resistors, or errors may occur.
BIPOLAR OUTPUTS
By connecting the output of the ADR44x to the inverting ter-
minal of an operational amplifier, it is possible to obtain both
positive and negative reference voltages. Care must be taken
when choosing Resistors R1 and R2 (see Figure 36). These
resistors must be matched as closely as possible to ensure mini-
mal differences between the negative and positive outputs. In
addition, care must be taken to ensure performance over
temperature. Use low temperature coefficient resistors if the
circuit is used over temperature; otherwise, differences exist
between the two outputs.
ADR440/
ADR441/
ADR443/
ADR444/
ADR445
6
2
4
V
IN
V
OUT
GND R1
10kΩR2
10kΩ
R3
5kΩ
–10V
+10V
–5V
+5V
0.1µF
0.1µF
05428-036
+
V
DD
Figure 36. ADR44x Bipolar Outputs
PROGRAMMABLE VOLTAGE SOURCE
To obtain different voltages than those offered by the ADR44x,
some extra components are needed. In Figure 37, two potenti-
ometers are used to set the desired voltage and the buffering
amplifier provides current drive. The potentiometer connected
between VOUT and GND, with its wiper connected to the
noninverting input of the operational amplifier, takes care of
coarse trim. The second potentiometer, with its wiper connected
to the trim terminal of the ADR44x, is used for fine adjustment.
Resolution depends on the end-to-end resistance value and the
resolution of the selected potentiometer.
ADR440/
ADR441/
ADR443/
ADR444/
ADR445
6
2
4
V
IN
V
OUT
GND R2
10kΩ
ADJ V
REF
05428-038
+
V
DD
R1
10kΩ
Figure 37. Programmable Voltage Source
For a completely programmable solution, replace the two
potentiometers in Figure 37 with one Analog Devices dual
digital potentiometer, offered with either an SPI or an I2C
interface. These interfaces set the position of the wiper on both
potentiometers and allow the output voltage to be set. Table 9
lists compatible Analog Devices digital potentiometers.
ADR440/ADR441/ADR443/ADR444/ADR445
Rev. E | Page 16 of 20
Table 9. Digital Potentiometer Parts
Part No.
No. of
Channels
No. of
Positions ITF R (kΩ)
VDD1
(V)
AD5251 2.00 64.00 I2C 1, 10, 50, 100 5.5
AD5207 2.00 256.00 SPI 10, 50, 100 5.5
AD5242 2.00 256.00 I2C 10, 100, 1M 5.5
AD5262 2.00 256.00 SPI 20, 50, 200 15
AD5282 2.00 256.00 I2C 20, 50, 100 15
AD5252 2.00 256.00 I2C 1, 10, 50, 100 5.5
AD5232 2.00 256.00 SPI 10, 50, 100 5.5
AD5235 2.00 1024.00 SPI 25, 250 5.5
ADN2850 2.00 1024.00 SPI 25, 250 5.5
1 Can also use a negative supply.
Adding a negative supply to the operational amplifier allows
the user to produce a negative programmable reference
by connecting the reference output to the inverting terminal
of the operational amplifier. Choose feedback resistors to
minimize errors over temperature.
PROGRAMMABLE CURRENT SOURCE
It is possible to build a programmable current source using a
setup similar to the programmable voltage source, as shown in
Figure 38. The constant voltage on the gate of the transistor sets
the current through the load. Varying the voltage on the gate
changes the current. This circuit does not require a dual digital
potentiometer.
ADR440/
ADR441/
ADR443/
ADR444/
ADR445
V
IN
V
OUT
GND
I
LOAD
V
CC
R
SENSE
AD5259
2
6
4
0.1µF
0.1µF
05428-039
Figure 38. Programmable Current Source
HIGH VOLTAGE FLOATING CURRENT SOURCE
Use the circuit in Figure 39 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.
ADR440/
ADR441/
ADR443/
ADR444/
ADR445
V
IN
V
OUT
GND OP90
+
V
S
SST111
VISHAY
2N3904
–V
S
05428-040
2
6
4
Figure 39. Floating Current Source
PRECISION OUTPUT REGULATOR
(BOOSTED REFERENCE)
ADR440/
ADR441/
ADR443/
ADR444/
ADR445
6
2
VIN
VOUT RL
200ΩCL
1µF
2N7002
–V
15V
VO
CIN
0.1µF
COUT
0.1µF
V
IN
GND
4
0
5428-041
Figure 40. Boosted Output Reference
Higher current drive capability can be obtained without
sacrificing accuracy by using the circuit in Figure 40. The
operational amplifier regulates the MOSFET turn-on, forcing
VO to equal the VREF. Current is then drawn from VIN, allowing
increased current drive capability. The circuit allows a 50 mA
load; if higher current drive is required, use a larger MOSFET.
For fast transient response, add a buffer at VO to aid with
capacitive loading.
ADR440/ADR441/ADR443/ADR444/ADR445
Rev. E | Page 17 of 20
OUTLINE DIMENSIONS
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.
COMPLIANT TO JEDEC STANDARDS MS-012-AA
012407-A
0.25 (0.0098)
0.17 (0.0067)
1.27 (0.0500)
0.40 (0.0157)
0.50 (0.0196)
0.25 (0.0099) 45°
8°
0°
1.75 (0.0688)
1.35 (0.0532)
SEATING
PLANE
0.25 (0.0098)
0.10 (0.0040)
4
1
85
5.00(0.1968)
4.80(0.1890)
4.00 (0.1574)
3.80 (0.1497)
1.27 (0.0500)
BSC
6.20 (0.2441)
5.80 (0.2284)
0.51 (0.0201)
0.31 (0.0122)
COPLANARITY
0.10
Figure 41. 8-Lead Standard Small Outline Package [SOIC_N]
Narrow Body
(R-8)
Dimensions shown in millimeters and (inches)
COMPLIANT TO JEDEC STANDARDS MO-187-AA
6°
0°
0.80
0.55
0.40
4
8
1
5
0.65 BSC
0.40
0.25
1.10 MAX
3.20
3.00
2.80
COPLANARITY
0.10
0.23
0.09
3.20
3.00
2.80
5.15
4.90
4.65
PIN 1
IDENTIFIER
15° MAX
0.95
0.85
0.75
0.15
0.05
10-07-2009-B
Figure 42. 8-Lead Mini Small Outline Package [MSOP]
(RM-8)
Dimensions show in millimeters
ADR440/ADR441/ADR443/ADR444/ADR445
Rev. E | Page 18 of 20
ORDERING GUIDE
Initial
Accuracy
Model1
Output
Voltage (V) ±mV %
Temperature
Coefficient
Package (ppm/°C)
Package
Description Branding
Temperature
Range
Package
Option
ADR440ARZ 2.048 3 0.15 10 8-Lead SOIC_N –40°C to +125°C R-8
ADR440ARZ-REEL7 2.048 3 0.15 10 8-Lead SOIC_N –40°C to +125°C R-8
ADR440ARMZ 2.048 3 0.15 10 8-Lead MSOP R01 –40°C to +125°C RM-8
ADR440ARMZ-REEL7 2.048 3 0.15 10 8-Lead MSOP R01 –40°C to +125°C RM-8
ADR440BRZ 2.048 1 0.05 3 8-Lead SOIC_N –40°C to +125°C R-8
ADR440BRZ-REEL7 2.048 1 0.05 3 8-Lead SOIC_N –40°C to +125°C R-8
ADR441ARZ 2.500 3 0.12 10 8-Lead SOIC_N –40°C to +125°C R-8
ADR441ARZ-REEL7 2.500 3 0.12 10 8-Lead SOIC_N –40°C to +125°C R-8
ADR441ARMZ 2.500 3 0.12 10 8-Lead MSOP R02 –40°C to +125°C RM-8
ADR441ARMZ-REEL7 2.500 3 0.12 10 8-Lead MSOP R02 –40°C to +125°C RM-8
ADR441BRZ 2.500 1 0.04 3 8-Lead SOIC_N –40°C to +125°C R-8
ADR441BRZ-REEL7 2.500 1 0.04 3 8-Lead SOIC_N –40°C to +125°C R-8
ADR443ARZ 3.000 4 0.13 10 8-Lead SOIC_N –40°C to +125°C R-8
ADR443ARZ-REEL7 3.000 4 0.13 10 8-Lead SOIC_N –40°C to +125°C R-8
ADR443ARMZ 3.000 4 0.13 10 8-Lead MSOP R03 –40°C to +125°C RM-8
ADR443ARMZ-REEL7 3.000 4 0.13 10 8-Lead MSOP R03 –40°C to +125°C RM-8
ADR443BRZ 3.000 1.2 0.04 3 8-Lead SOIC_N –40°C to +125°C R-8
ADR443BRZ-REEL7 3.000 1.2 0.04 3 8-Lead SOIC_N –40°C to +125°C R-8
ADR444ARZ 4.096 5 0.13 10 8-Lead SOIC_N –40°C to +125°C R-8
ADR444ARZ-REEL7 4.096 5 0.13 10 8-Lead SOIC_N –40°C to +125°C R-8
ADR444ARMZ 4.096 5 0.13 10 8-Lead MSOP R04 –40°C to +125°C RM-8
ADR444ARMZ-REEL7 4.096 5 0.13 10 8-Lead MSOP R04 –40°C to +125°C RM-8
ADR444BRZ 4.096 1.6 0.04 3 8-Lead SOIC_N –40°C to +125°C R-8
ADR444BRZ-REEL7 4.096 1.6 0.04 3 8-Lead SOIC_N –40°C to +125°C R-8
ADR445ARZ 5.000 6 0.12 10 8-Lead SOIC_N –40°C to +125°C R-8
ADR445ARZ-REEL7 5.000 6 0.12 10 8-Lead SOIC_N –40°C to +125°C R-8
ADR445ARMZ 5.000 6 0.12 10 8-Lead MSOP R05 –40°C to +125°C RM-8
ADR445ARMZ-REEL7 5.000 6 0.12 10 8-Lead MSOP R05 –40°C to +125°C RM-8
ADR445BRZ 5.000 2 0.04 3 8-Lead SOIC_N –40°C to +125°C R-8
ADR445BRZ-REEL7 5.000 2 0.04 3 8-Lead SOIC_N –40°C to +125°C R-8
1 Z = RoHS Compliant Part.
ADR440/ADR441/ADR443/ADR444/ADR445
Rev. E | Page 19 of 20
NOTES
ADR440/ADR441/ADR443/ADR444/ADR445
Rev. E | Page 20 of 20
NOTES
I2C refers to a communications protocol originally developed by Philips Semiconductors (now NXP Semiconductors).
©2005–2010 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D05428-0-11/10(E)