AD ADR441

Ultralow Noise, LDO XFET® Voltage
References with Current Sink and Source
ADR440/ADR441/ADR443/ADR444/ADR445
PIN CONFIGURATIONS
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:
3 ppm/°C (B Grade)
10 ppm/°C (A Grade)
Low dropout operation: 500 mV
Input range: (VOUT + 500 mV) to 18 V
High output current: +10 mA/−5 mA
Wide temperature range: −40°C to +125°C
TP 1
VIN 2
NC 3
ADR44x
TOP VIEW
(Not to Scale)
GND 4
8
TP
7
NC
6
VOUT
5
TRIM
NC = NO CONNECT
05428-002
FEATURES
Figure 1. 8-Lead SOIC (R)
TP 1
ADR44x
VIN 2
8
TP
7
NC
6 VOUT
TOP VIEW
GND 4 (Not to Scale) 5 TRIM
NC = NO CONNECT
05428-001
NC 3
Figure 2. 8-Lead MSOP (RM)
APPLICATIONS
Precision data acquisition systems
High resolution data converters
Battery-powered instrumentations
Portable medical instruments
Industrial process control systems
Precision instruments
Optical control circuits
GENERAL DESCRIPTION
The ADR44x series is a family of XFET® voltage references
featuring ultralow noise, high accuracy, and low temperature
drift performance. Using ADI’s patented temperature drift
curvature correction and XFET (eXtra implanted junction FET)
technology, the ADR44x family’s voltage change vs. temperature
nonlinearity is greatly minimized.
The XFET references offer better noise performance than
buried-Zener references, and XFET references operate off
low supply 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 requirements.
The ADR44x family has the capability to source up to 10 mA
and sink up to 5 mA of output current. It also comes with a
TRIM terminal to adjust the output voltage over a 0.5% range
without compromising any performance.
Offered in two electrical grades, the ADR44x family is available in the 8-lead SOIC and MSOP packages. All versions
are specified over the extended industrial temperature range
(−40oC to +125oC).
Table 1. Selection Guide
Model
ADR440B
ADR440A
ADR441B
ADR441A
ADR443B
ADR443A
ADR444B
ADR444A
ADR445B
ADR445A
VOUT (V)
2.048
2.048
2.500
2.500
3.000
3.000
4.096
4.096
5.000
5.000
Accuracy (mV)
±1
±3
±1
±3
±1.2
±4
±1.6
±5
±2
±6
Temperature
Coefficient (ppm/°C)
3
10
3
10
3
10
3
10
3
10
Rev. 0
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.
ADR440/ADR441/ADR443/ADR444/ADR445
TABLE OF CONTENTS
Features .............................................................................................. 1
Theory of Operation ...................................................................... 14
Applications....................................................................................... 1
Power Dissipation Considerations........................................... 14
Pin Configurations ........................................................................... 1
Basic Voltage Reference Connections ..................................... 14
General Description ......................................................................... 1
Noise Performance..................................................................... 14
Revision History ............................................................................... 2
Turn-On Time ............................................................................ 14
Specifications..................................................................................... 3
Applications..................................................................................... 15
ADR440—Electrical Characteristics.......................................... 3
Output Adjustment .................................................................... 15
ADR441—Electrical Characteristics.......................................... 4
Bipolar Outputs .......................................................................... 15
ADR443—Electrical Characteristics.......................................... 5
Negative Reference ..................................................................... 15
ADR444—Electrical Characteristics.......................................... 6
Programmable Voltage Source ................................................. 16
ADR445—Electrical Characteristics.......................................... 7
Programmable Current Source ................................................ 16
Absolute Maximum Ratings............................................................ 8
High Voltage Floating Current Source .................................... 16
Package Type ................................................................................. 8
Precision Output Regulator (Boosted Reference).................. 17
ESD Caution.................................................................................. 8
Outline Dimensions ....................................................................... 18
Typical Performance Characteristics ............................................. 9
Ordering Guide .......................................................................... 19
REVISION HISTORY
10/05—Revision 0: Initial Version
Rev. 0 | Page 2 of 20
ADR440/ADR441/ADR443/ADR444/ADR445
SPECIFICATIONS
ADR440—ELECTRICAL CHARACTERISTICS
VIN = 3 V to 18 V; TA = 25°C; CIN, CBYPASS = 0.1 μF, unless otherwise noted.
Table 2.
Parameter
OUTPUT VOLTAGE
A Grade
B Grade
INITIAL ACCURACY
A Grade
B Grade
TEMPERATURE DRIFT
A Grade SOIC-8
MSOP-8
B Grade SOIC-8
LINE REGULATION
LOAD REGULATION
Symbol
VO
VO
1
Min
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
%
10
10
3
+20
ppm/°C
ppm/°C
ppm/°C
ppm/V
+50
ppm/mA
+50
3.75
ppm/mA
mA
μV p-p
nV/√Hz
μs
ppm
ppm
dB
mA
V
mV
VOERR
VOERR
TC VO
TC VO
TC VO
ΔVO/ΔVIN
ΔVO/ΔILOAD
QUIESCENT CURRENT
VOLTAGE NOISE
VOLTAGE NOISE DENSITY
TURN-ON SETTLING TIME
LONG-TERM STABILITY 1
OUTPUT VOLTAGE HYSTERISIS
RIPPLE REJECTION RATION
SHORT CIRCUIT TO GND
SUPPLY VOLTAGE OPERATING RANGE
SUPPLY VOLTAGE HEADROOM
Conditions
ΔVO/ΔILOAD
IIN
eN p-p
eN
tR
VO
VO_HYS
RRR
ISC
VIN
VIN − VO
−40°C < TA < +125°C
−40°C < TA < +125°C
−40°C < TA < +125°C
VIN = 3 V to 18 V, −40°C < TA < +125°C
ILOAD = 0 mA to 10 mA, VIN = 3.5 V
−40°C < TA < +125°C
ILOAD = 0 mA to −5 mA, VIN = 3.5 V
−40°C < TA < +125°C
No Load, −40°C < TA < +125°C
0.1 Hz to 10 Hz
1 kHz
−20
2
2
1
+10
−50
−50
3
1
60
10
50
70
−75
27
1,000 Hours
fIN = 10 kHz
3
500
18
The long-term stability specification is noncumulative. This drift in the subsequent 1,000-hour period is significantly lower than in the first 1,000-hour period.
Rev. 0 | Page 3 of 20
ADR440/ADR441/ADR443/ADR444/ADR445
ADR441—ELECTRICAL CHARACTERISTICS
VIN = 3 V to 18 V, TA = 25°C, unless otherwise noted.
Table 3.
Parameter
OUTPUT VOLTAGE
A Grade
B Grade
INITIAL ACCURACY
A Grade
B Grade
Symbol
VO
VO
Typ
Max
Unit
2.497
2.499
2.5
2.5
2.503
2.501
V
V
3
0.12
1
0.04
mV
%
mV
%
10
10
3
20
ppm/°C
ppm/°C
ppm/°C
ppm/V
+50
ppm/mA
+50
3.75
ppm/mA
mA
μV p-p
nV/√Hz
μs
ppm
ppm
dB
mA
V
mV
VOERR
TC VO
TC VO
TC VO
ΔVO/ΔVIN
LOAD REGULATION
ΔVO/ΔILOAD
ΔVO/ΔILOAD
1
Min
VOERR
TEMPERATURE DRIFT
A Grade SOIC-8
MSOP-8
B Grade SOIC-8
LINE REGULATION
QUIESCENT CURRENT
VOLTAGE NOISE
VOLTAGE NOISE DENSITY
TURN-ON SETTLING TIME
LONG-TERM STABILITY 1
OUTPUT VOLTAGE HYSTERISIS
RIPPLE REJECTION RATION
SHORT CIRCUIT TO GND
SUPPLY VOLTAGE OPERATING RANGE
SUPPLY VOLTAGE HEADROOM
Conditions
IIN
eN p-p
eN
tR
VO
VO_HYS
RRR
ISC
VIN
VIN − VO
−40°C < TA < +125°C
−40°C < TA < +125°C
−40°C < TA < +125°C
VIN = 3 V to 18 V,
−40°C < TA < +125°C
ILOAD = 0 mA to 10 mA, VIN = 4 V
−40°C < TA < +125°C
ILOAD = 0 mA to −5 mA, VIN = 4 V
−40°C < TA < +125°C
No Load, −40°C < TA < +125°C
0.1 Hz to 10 Hz
1 kHz
2
2
1
10
−50
−50
3
1.2
48
10
50
70
−75
27
1,000 Hours
fIN = 10 kHz
3
500
18
The long-term stability specification is noncumulative. This drift in subsequent 1,000-hour period is significantly lower than in the first 1,000-hour period.
Rev. 0 | Page 4 of 20
ADR440/ADR441/ADR443/ADR444/ADR445
ADR443—ELECTRICAL CHARACTERISTICS
VIN = 3.5 V to 18 V, TA = 25°C, unless otherwise noted.
Table 4.
Parameter
OUTPUT VOLTAGE
A Grade
B Grade
INITIAL ACCURACY
A Grade
B Grade
TEMPERATURE DRIFT
A Grade SOIC-8
MSOP-8
B Grade SOIC-8
LINE REGULATION
LOAD REGULATION
Symbol
VO
VO
TURN-ON SETTLING TIME
LONG-TERM STABILITY 1
OUTPUT VOLTAGE HYSTERISIS
RIPPLE REJECTION RATION
SHORT CIRCUIT TO GND
SUPPLY VOLTAGE OPERATING RANGE
SUPPLY VOLTAGE HEADROOM
1
Min
Typ
Max
Unit
2.996
2.9988
3.0
3.0
3.004
3.0012
V
V
4
0.13
1.2
0.04
mV
%
mV
%
10
10
3
20
ppm/°C
ppm/°C
ppm/°C
ppm/V
+50
ppm/mA
+50
3.75
ppm/mA
mA
μV p-p
VOERR
VOERR
TC VO
TC VO
TC VO
ΔVO/ΔVIN
ΔVO/ΔILOAD
ΔVO/ΔILOAD
QUIESCENT CURRENT
VOLTAGE NOISE
VOLTAGE NOISE DENSITY
Conditions
IIN
eN p-p
eN
tR
VO
VO_HYS
RRR
ISC
VIN
VIN − VO
−40°C < TA < +125°C
−40°C < TA < +125°C
−40°C < TA < +125°C
VIN = 3.5 V to 18 V, −40°C < TA < +125°C
ILOAD = 0 mA to 10 mA, VIN = 5 V
−40°C < TA < +125°C
ILOAD = 0 mA to −5 mA, VIN = 5 V
−40°C < TA < +125°C
No Load, −40°C < TA < +125°C
0.1 Hz to 10 Hz
2
2
1
10
−50
−50
3
1.4
1 kHz
64
10
50
70
−75
27
1,000 Hours
fIN = 10 kHz
3.5
500
18
nV/√Hz
μs
ppm
ppm
dB
mA
V
mV
The long-term stability specification is noncumulative. This drift in the subsequent 1,000-hour period is significantly lower than in the first 1,000-hour period.
Rev. 0 | Page 5 of 20
ADR440/ADR441/ADR443/ADR444/ADR445
ADR444—ELECTRICAL CHARACTERISTICS
VIN = 4.6 V to 18 V, TA = 25°C, unless otherwise noted.
Table 5.
Parameter
OUTPUT VOLTAGE
A Grade
B Grade
INITIAL ACCURACY
A Grade
B Grade
TEMPERATURE DRIFT
A Grade SOIC-8
MSOP-8
B Grade SOIC-8
LINE REGULATION
LOAD REGULATION
Symbol
VO
VO
1
Min
Typ
Max
Unit
4.091
4.0944
4.096
4.096
4.101
4.0976
V
V
5
0.13
1.6
0.04
mV
%
mV
%
10
10
3
20
ppm/°C
ppm/°C
ppm/°C
ppm/V
+50
ppm/mA
+50
3.75
ppm/mA
mA
μV p-p
nV/√Hz
μs
ppm
ppm
dB
mA
V
mV
VOERR
VOERR
TC VO
TC VO
TC VO
ΔVO/ΔVIN
ΔVO/ΔILOAD
ΔVO/ΔILOAD
QUIESCENT CURRENT
VOLTAGE NOISE
VOLTAGE NOISE DENSITY
TURN-ON SETTLING TIME
LONG-TERM STABILITY 1
OUTPUT VOLTAGE HYSTERISIS
RIPPLE REJECTION RATION
SHORT CIRCUIT TO GND
SUPPLY VOLTAGE OPERATING RANGE
SUPPLY VOLTAGE HEADROOM
Conditions
IIN
eN p-p
eN
tR
VO
VO_HYS
RRR
ISC
VIN
VIN − VO
−40°C < TA < +125°C
−40°C < TA < +125°C
−40°C < TA < +125vC
VIN = 4.6 V to 18 V, −40°C < TA < +125°C
ILOAD = 0 mA to 10 mA, VIN = 5.5 V
−40°C < TA < +125°C
ILOAD = 0 mA to −5 mA, VIN = 5.5 V
−40°C < TA < +125°C
No Load, −40°C < TA < +125°C
0.1 Hz to 10 Hz
1 kHz
2
2
1
10
−50
−50
3
1.8
64
10
50
70
−75
27
1,000 Hours
fIN = 10 kHz
4.6
500
18
The long-term stability specification is noncumulative. This drift in the subsequent 1,000-hour period is significantly lower than in the first 1,000-hour period.
Rev. 0 | Page 6 of 20
ADR440/ADR441/ADR443/ADR444/ADR445
ADR445—ELECTRICAL CHARACTERISTICS
VIN = 5.5 V to 18 V, TA = 25°C unless otherwise noted.
Table 6.
Parameter
OUTPUT VOLTAGE
A Grade
B Grade
INITIAL ACCURACY
A Grade
B Grade
TEMPERATURE DRIFT
A Grade SOIC-8
MSOP-8
B Grade SOIC-8
LINE REGULATION
LOAD REGULATION
Symbol
VO
VO
1
Min
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
%
10
10
3
20
ppm/°C
ppm/°C
ppm/°C
ppm/V
+50
ppm/mA
+50
3.75
ppm/mA
mA
μV p-p
nV/√Hz
μs
ppm
ppm
dB
mA
V
mV
VOERR
VOERR
TC VO
TC VO
TC VO
ΔVO/ΔVIN
ΔVO/ΔILOAD
ΔVO/ΔILOAD
QUIESCENT CURRENT
VOLTAGE NOISE
VOLTAGE NOISE DENSITY
TURN-ON SETTLING TIME
LONG-TERM STABILITY 1
OUTPUT VOLTAGE HYSTERISIS
RIPPLE REJECTION RATION
SHORT CIRCUIT TO GND
SUPPLY VOLTAGE OPERATING RANGE
SUPPLY VOLTAGE HEADROOM
Conditions
IIN
eN p-p
eN
tR
VO
VO_HYS
RRR
ISC
VIN
VIN − VO
−40°C < TA < +125°C
−40°C < TA < +125°C
−40°C < TA < +125°C
VIN = 5.5 V to 18 V, −40°C < TA < +125°C
ILOAD = 0 mA to 10 mA, VIN = 6.5 V
−40°C < TA < +125°C
ILOAD = 0 mA to −5 mA, VIN = 6.5 V
−40°C < TA < +125°C
No Load, −40°C < TA < +125°C
0.1 Hz to 10 Hz
1 kHz
2
2
1
10
−50
−50
3
2.25
64
10
50
70
–75
27
1,000 Hours
fIN = 10 kHz
5.5
500
18
The long-term stability specification is noncumulative. This drift in the subsequent 1,000-hour period is significantly lower than in the first 1,000-hour period.
Rev. 0 | Page 7 of 20
ADR440/ADR441/ADR443/ADR444/ADR445
ABSOLUTE MAXIMUM RATINGS
At 25°C, unless otherwise noted.
Table 7.
Parameter
Supply Voltage
Output Short-Circuit Duration to GND
Storage Temperature Range
R, RM Packages
Operating Temperature Range
Junction Temperature Range
Lead Temperature Range (Soldering, 60 sec)
Rating
20 V
Indefinite
−65°C to +125°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.
PACKAGE TYPE
Table 8.
Package Type
8-Lead SOIC (R)
8-Lead MSOP (RM)
1
θJA 1
130
190
θJC
43
Unit
°C/W
°C/W
θJA is specified for worst-case conditions (device soldered in circuit board for
surface mount packages). Contact sales for the latest information of release
dates.
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on
the human body and test equipment and can discharge without detection. Although this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.
Rev. 0 | Page 8 of 20
ADR440/ADR441/ADR443/ADR444/ADR445
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 7V, TA = 25oC; CIN, CBYPASS = 0.1 μF; unless otherwise noted.
2.5020
4.0
SUPPLY CURRENT (mA)
OUTPUT VOLTAGE (V)
2.5015
2.5010
2.5005
2.5000
3.5
+125°C
+25°C
3.0
–40°C
2.5
–25
–10
5
20
35
50
65
TEMPERATURE (°C)
80
95
110
05428-006
2.4990
–40
05428-003
2.4995
2.0
4
125
6
8
10
12
14
INPUT VOLTAGE (V)
16
18
Figure 6. ADR441 Supply Current vs. Input Voltage
Figure 3. ADR441 VOUT vs. Temperature
3.0020
4.0
3.0015
VOUT (V)
3.0005
3.0000
2.9995
2.9990
2.9980
–40
05428-004
2.9985
–25
–10
5
20
35
50
65
TEMPERATURE (°C)
80
95
110
3.5
3.0
2.5
2.0
–40
125
Figure 4. ADR444 VOUT vs. Temperature
05428-007
SUPPLY CURRENT (mA)
3.0010
–25
–10
5
20
35
50
65
TEMPERATURE (°C)
80
95
110
125
Figure 7. ADR441 Supply Current vs. Temperature
4.0980
3.5
4.0975
3.4
3.3
SUPPLY CURRENT (mA)
4.0970
4.0960
4.0955
4.0950
3.2
3.1
+125°C
3.0
2.9
+25°C
2.8
2.7
4.0940
–40
–25
–10
5
20
35
50
65
TEMPERATURE (°C)
80
95
110
–40°C
05428-008
4.0945
05428-005
VOUT (V)
4.0965
2.6
2.5
5.3
125
Figure 5. ADR445 VOUT vs. Temperature
7.3
9.3
11.3
13.3
15.3
INPUT VOLTAGE (V)
17.3
Figure 8. ADR445 Supply Current vs. Input Voltage
Rev. 0 | Page 9 of 20
19.3
ADR440/ADR441/ADR443/ADR444/ADR445
3.25
7
LINE REGULATIOIN (ppm/V)
QUIESCENT CURRENT (mA)
6
3.15
3.05
2.95
5
4
3
2
2.85
–25
–10
5
20
35
50
65
TEMPERATURE (°C)
80
95
110
0
–40
125
Figure 9. ADR445 Quiescent Current vs. Temperature
05428-012
05428-009
2.75
–40
1
–25
–10
5
20
35
50
65
TEMPERATURE (°C)
80
95
110
125
Figure 12. ADR445 Line Regulation vs. Temperature
10
50
6
4
0
–40
05428-010
2
–25
–10
5
20
35
50
65
TEMPERATURE (°C)
80
95
110
30
20
0mA TO +10mA LOAD
10
0
–10
0mA TO –5mA LOAD
–20
–30
–40
–50
–40
125
Figure 10. ADR441 Line Regulation vs. Temperature
–25
–10
5
20
35
50
65
TEMPERATURE (°C)
80
95
110
125
Figure 13. ADR445 Load Regulation vs. Temperature
60
0.7
0.6
DIFFERENTIAL VOLTAGE (V)
55
50
IL = 0mA TO 10 mA
45
VIN = 6V
40
35
30
–40
–25
–10
5
20
35
50
65
TEMPERATURE (°C)
80
95
110
+125°C
0.5
0.4
+25°C
0.3
–40°C
0.2
0.1
0
–10
125
05428-014
VIN = 18V
05428-011
LOAD REGULATION (ppm/mA)
05428-013
LOAD REGULATION (ppm/mA)
LINE REGULATION (ppm/V)
40
8
–5
0
LOAD CURRENT (mA)
5
Figure 14. ADR441 Minimum Input/Output
Differential Voltage vs. Load Current
Figure 11. ADR441 Load Regulation vs. Temperature
Rev. 0 | Page 10 of 20
10
ADR440/ADR441/ADR443/ADR444/ADR445
0.5
CIN, COUT = 0.1μF
NO LOAD
MINIMUM HEADROOM (V)
0.4
VIN = 5V/DIV
0.3
0.2
0.1
–25
–10
5
20
35
50
65
TEMPERATURE (°C)
80
95
110
TIME = 10μs/DIV
125
Figure 15. ADR441 Minimum Headroom vs. Temperature
05428-018
05428-015
0
–40
VOUT = 1V/DIV
Figure 18. ADR441 Turn-On Response
1.0
CIN, COUT = 0.1μF
0.8
+125°C
0.7
VIN = 5V/DIV
0.6
0.5
+25°C
0.4
–40°C
0.3
0.2
05428-016
0.1
0
–5
0
5
LOAD CURRENT (mA)
VOUT = 1V/DIV
10
05428-019
DIFFERENTIAL VOLTAGE (V)
0.9
TIME = 200μs/DIV
Figure 19. ADR441 Turn-Off Response
Figure 16. ADR445 Minimum Input/Output
Differential Voltage vs. Load Current
CIN = 0.1μF
COUT = 10μF
0.5
NO LOAD
VIN = 5V/DIV
0.3
0.2
0
–40
–25
–10
5
20
35
50
65
TEMPERATURE (°C)
80
95
110
TIME = 200μs/DIV
125
Figure 20. ADR441 Turn-On Response
Figure 17. ADR445 Minimum Headroom vs. Temperature
Rev. 0 | Page 11 of 20
05428-020
VOUT = 1V/DIV
0.1
05428-017
MINIMUM HEADROOM (V)
0.4
ADR440/ADR441/ADR443/ADR444/ADR445
CIN = 0.1μF
COUT = 10μF
2V/DIV
4V
1μV/DIV
CH1 p-p
1.18μV
TIME = 1s/DIV
Figure 21. ADR441 Line Transient Response
05428-024
100μs/DIV
05428-021
2mV/DIV
Figure 24. ADR441 0.1 Hz to 10.0 Hz Voltage Noise
CIN, COUT = 0.1μF
LOAD OFF
LOAD ON
50μV/DIV
CH1 p-p
49μV
1
05428-025
200μs/DIV
05428-022
5mV/DIV
TIME = 1s/DIV
Figure 22. ADR441 Load Transient Response
Figure 25. ADR441 10 Hz to 10 kHz Voltage Noise
CIN = 0.1μF
COUT = 10μF
LOAD OFF
LOAD ON
1μV/DIV
CH1 p-p
2.24μV
TIME = 1s/DIV
Figure 26. ADR445 0.1 Hz to 10.0 Hz Voltage Noise
Figure 23. ADR441 Load Transient Response
Rev. 0 | Page 12 of 20
05428-026
200μs/DIV
05428-023
5mV/DIV
ADR440/ADR441/ADR443/ADR444/ADR445
10
9
50μV/DIV
CH1 p-p
66μV
OUTPUT IMPEDANCE (Ω)
8
7
ADR445
6
5
ADR443
4
3
ADR441
1
0
05428-027
TIME = 1s/DIV
100
1k
FREQUENCY (Hz)
10k
100k
Figure 29. Output Impedance vs. Frequency
Figure 27. ADR445 10 Hz to 10 kHz Voltage Noise
16
0
–10
12
–20
RIPPLE REJECTION (dB)
14
10
8
6
4
–30
–40
–50
–60
–70
05428-028
–90
–100
150
130
90
110
70
50
30
10
–10
–30
–50
–70
–90
–110
–130
0
05428-030
–80
2
–150
NUMBER OF PARTS
10
05428-029
2
DEVIATION (PPM)
100
1k
10k
FREQUENCY (Hz)
100k
Figure 30. Ripple Rejection vs. Frequency
Figure 28. ADR441 Typical Hysteresis
Rev. 0 | Page 13 of 20
1M
ADR440/ADR441/ADR443/ADR444/ADR445
THEORY OF OPERATION
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 can
be closely compensated for by adding a correction term generated
in the same fashion as the proportional-to-temperature (PTAT)
term used to compensate band gap references. The advantage
of an XFET reference is the correction term is approximately
20 times lower and requires less correction than a band gap
reference. This results in much lower noise, because most of
the noise of a band gap reference results from the temperature
compensation circuitry.
POWER DISSIPATION CONSIDERATIONS
The ADR44x family of references is guaranteed to deliver load
currents to 10 mA with an input voltage that ranges from 2.6 V
to 18 V. When these devices are used in applications at higher
currents, users should use the following equation to account for
the temperature effects due to the power dissipation increases.
TJ = PD × θ JA + TA
where:
TJ and TA are the junction and ambient temperatures.
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 output for stability. While not required for operation,
a 10 μF capacitor at the input can help with line voltage
transient performance.
TP 1
VIN
)
2
+
Figure 31 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 absolute temperature.
The general equation is
VOUT = G × (ΔVP − R1 × I PTAT
(2)
10μF
0.1μF
ADR44x
8
TP
7
NIC
OUTPUT
NIC 3
TOP VIEW
6
(Not to Scale)
4
5
TRIM
NOTES
1. NIC = NO INTERNAL CONNECTION
2. TP = TEST PIN (DO NOT CONNECT)
(1)
0.1μF
05428-034
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.
Figure 32. Basic Voltage Reference Configuration
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.
ADR44x devices are created by on-chip adjustment of R2 and
R3 to achieve the different voltage option at the reference
output.
VIN
I1
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 24 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 made of a 2pole high-pass filter with a corner frequency at 0.1 Hz and a 2pole low-pass filter with a corner frequency at 10.0 Hz.
I1
TURN-ON TIME
ADR44x
IPTAT
VOUT
R2
1
R1
R3
1EXTRA
CHANNEL IMPLANT
VOUT = G(ΔVP – R1 × IPTAT)
GND
05428-033
ΔVP
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 components 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 18 and Figure 19 show the turn-on and
turn-off settling times for the ADR441.
Figure 31. Simplified Schematic Device
Rev. 0 | Page 14 of 20
ADR440/ADR441/ADR443/ADR444/ADR445
+VDD
APPLICATIONS
OUTPUT ADJUSTMENT
2
VIN
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 both errors from the reference and overall system errors
to be trimmed out by connecting a potentiometer between the
output and ground, with the wiper connected to the TRIM pin.
Figure 33 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.
0.1μF
ADR445
VOUT 6
+5V
0.1μF
GND
R1
R2
10kΩ 10kΩ
4
+10V
05428-036
–5V
R3
5kΩ
–10V
Figure 34. ADR 44x Bipolar Outputs
0.1μF
NEGATIVE REFERENCE
2
VIN
R1
RP
R2
05428-035
4
Figure 33. ADR44x Trim Function
Using the trim function had a negligible effect on the
temperature performance of the ADR44x family. However, all
resistors used need to be low temperature coefficient resistors,
or errors can occur.
+VDD
2
VIN
6
BIPOLAR OUTPUTS
By connecting the output of the ADR44x to the inverting
terminal of an op amp, it is possible to obtain both positive
and negative reference voltages. Care must be taken when
choosing Resistor R1 and Resistor R2 (see Figure 34). They
must be matched as closely as possible to ensure minimal
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 to be used over temperature; otherwise, differences will
exist between the two outputs.
VOUT
ADR44x
GND
4
–VREF
–VDD
05428-037
0.1μF
ADR44x
TRIM 5
GND
Figure 35 shows how to connect the ADR44x and a standard
op amp, such as the OP1177, to provide negative voltage.
This configuration provides two main advantages: First, it
only requires two devices; therefore, it does not require
excessive board space. Second, and more importantly, it does
not require any external resistors. This means the performance
of this circuit does not rely on choosing low TC resistors to
ensure accuracy.
VO = ±0.5%
VOUT 6
Figure 35. Negative Reference
VOUT is at virtual ground, and the negative reference is taken
directly from the output of the op amp. If the negative supply
voltage is close to the reference output, the op amp must be
dual supply and have low offset and rail-to-rail capability.
Rev. 0 | Page 15 of 20
ADR440/ADR441/ADR443/ADR444/ADR445
PROGRAMMABLE VOLTAGE SOURCE
PROGRAMMABLE CURRENT SOURCE
To obtain different voltages than those offered by the ADR44x,
some extra components are needed. In Figure 36,
two potentiometers are used to set the desired voltage, while the
buffering amplifier provides current drive. The potentiometer
connected between VOUT and ground, with its wiper connected
to the noninverting input of the op amp, 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.
It is possible to build a programmable current source using a
similar setup as the programmable voltage source, as shown in
Figure 37. 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.
VCC
0.1μF
2
VIN
RSENSE
VOUT 6
+VDD
GND
0.1μF
4
2
AD5259
VIN
LOAD
VOUT 6
R1
R2
10kΩ 10kΩ
Figure 37. Programmable Current Source
05428-038
4
HIGH VOLTAGE FLOATING CURRENT SOURCE
Figure 36. Programmable Voltage Source
For a completely programmable solution, replace the two
potentiometers in Figure 36 with one of ADI’s dual digital
potentiometers, which offer either SPI® or I2C interfaces. These
interfaces set the position of the wiper on both potentiometers
and allow the output voltage to be set. Table 9 lists compatible
ADI digital potentiometers.
Use the circuit in Figure 38 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.
Table 9. Digital Potentiometer Parts
Part No.
AD5251
AD5207
AD5242
AD5262
AD5282
AD5252
AD5232
AD5235
ADN2850
1
No. Chan
2.00
2.00
2.00
2.00
2.00
2.00
2.00
2.00
2.00
No. Pos
64.00
256.00
256.00
256.00
256.00
256.00
256.00
1024.00
1024.00
ITF
I2C
SPI
I2C
SPI
I2C
I2C
SPI
SPI
SPI
+VS
SST111
VISHAY
2
R (kΩ)
1, 10, 50, 100
10, 50, 100
10, 100, 1M
20, 50, 200
20, 50, 100
1, 10, 50, 200
10, 50, 100
25, 250
25, 250
VDD1
5.5
5.5
5.5
15
15
5.5
5.5
5.5
5.5
Can also use a negative supply.
By adding a negative supply to the op amp, it is possible for
the user to also produce a negative programmable reference
by connecting the reference output to the inverting terminal
of the op amp. Choose feedback resistors to minimize errors
over temperature.
Rev. 0 | Page 16 of 20
VIN
ADR44x
VOUT 6
OP90
2N3904
GND
4
–VS
Figure 38. Floating Current Source
05428-040
GND
05428-039
ADJ VREF
ADR445
ADR440/ADR441/ADR443/ADR444/ADR445
PRECISION OUTPUT REGULATOR (BOOSTED
REFERENCE)
VIN
2
VIN
15V
ADR44x
VOUT 6
GND
4
VO
COUT
0.1μF
RL
200Ω
CL
1μF
–V
05428-041
CIN
0.1μF
2N7002
Figure 39. Boosted Output Reference
Higher current drive capability without sacrificing accuracy
can be obtained using the circuit in Figure 39. The op amp
regulates the MOSFET turn-on, which forces VO to equal the
VREF. Current is then drawn from VIN, which allows 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.
Rev. 0 | Page 17 of 20
ADR440/ADR441/ADR443/ADR444/ADR445
OUTLINE DIMENSIONS
5.00 (0.1968)
4.80 (0.1890)
8
5
4.00 (0.1574)
3.80 (0.1497) 1
4
6.20 (0.2440)
5.80 (0.2284)
1.27 (0.0500)
BSC
0.25 (0.0098)
0.10 (0.0040)
0.50 (0.0196)
× 45°
0.25 (0.0099)
1.75 (0.0688)
1.35 (0.0532)
0.51 (0.0201)
COPLANARITY
SEATING 0.31 (0.0122)
0.10
PLANE
8°
0.25 (0.0098) 0° 1.27 (0.0500)
0.40 (0.0157)
0.17 (0.0067)
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 40. 8-Lead Standard Small Outline Package [SOIC_N]
Narrow Body
(R-8)
Dimensions shown in millimeters and (inches)
3.00
BSC
8
3.00
BSC
1
5
4.90
BSC
4
PIN 1
0.65 BSC
1.10 MAX
0.15
0.00
0.38
0.22
COPLANARITY
0.10
0.23
0.08
8°
0°
SEATING
PLANE
COMPLIANT TO JEDEC STANDARDS MO-187-AA
Figure 41. 8-Lead Mini Small Outline Package [MSOP}
(RM-8)
Dimensions show in millimeters
Rev. 0 | Page 18 of 20
0.80
0.60
0.40
ADR440/ADR441/ADR443/ADR444/ADR445
ORDERING GUIDE
Model
ADR440ARZ 1
ADR440ARZ-REEL71
ADR440ARMZ1
ADR440ARMZ-REEL71
ADR440BRZ1
ADR440BRZ-REEL71
ADR441ARZ1
ADR441ARZ-REEL71
ADR441ARMZ1
ADR441ARMZ-REEL71
ADR441BRZ1
ADR441BRZ-REEL71
ADR443ARZ1
ADR443ARZ-REEL71
ADR443ARMZ1
ADR443ARMZ-REEL71
ADR443BRZ1
ADR443BRZ-REEL71
ADR444ARZ1
ADR444ARZ-REEL71
ADR444ARMZ1
ADR444ARMZ-REEL71
ADR444BRZ1
ADR444BRZ-REEL71
ADR445ARZ1
ADR445ARZ-REEL71
ADR445ARMZ1
ADR445ARMZ-REEL71
ADR445BRZ1
ADR445BRZ-REEL71
1
Output
Voltage
(VO) V
2.048
2.048
2.048
2.048
2.048
2.048
2.500
2.500
2.500
2.500
2.500
2.500
3.000
3.000
3.000
3.000
3.000
3.000
4.096
4.096
4.096
4.096
4.096
4.096
5.000
5.000
5.000
5.000
5.000
5.000
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
1
0.04
1
0.04
4
0.12
4
0.12
4
0.12
4
0.12
1.2
0.05
1.2
0.05
5
0.13
5
0.13
5
0.13
5
0.13
1.6
0.04
1.6
0.04
6
0.12
6
0.12
6
0.12
6
0.12
2
0.04
2
0.04
Temperature
Coefficient
Package
(ppm/°C)
10
10
10
10
3
3
10
10
10
10
3
3
10
10
10
10
3F
3
10
10
10
10
3
3
10
10
10
10
3
3
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 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
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
Z = Pb-free part.
Rev. 0 | Page 19 of 20
Branding
R01
R01
R02
R02
R03
R03
R04
R04
R05
R05
Temperature
Range (°C)
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40°C to +125°C
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40 to +125
–40 to +125
Ordering
Quantity
98
1,000
98
1,000
98
1,000
98
1,000
98
1,000
98
1,000
98
1,000
98
1,000
98
1,000
98
1,000
98
1,000
98
1,000
98
1,000
98
1,000
98
1,000
ADR440/ADR441/ADR443/ADR444/ADR445
NOTES
Purchase of licensed I2C components of Analog Devices or one of its sublicensed Associated Companies conveys a license for the purchaser under the Philips I2C Patent
Rights to use these components in an I2C system, provided that the system conforms to the I2C Standard Specification as defined by Philips.
© 2005 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D05428-0-10/05(0)
Rev. 0 | Page 20 of 20