AD ADR291GR-REEL7 Low noise micropower precision voltage reference Datasheet

Low Noise Micropower
2.048 V, 2.5 V, and 4.096 V
Precision Voltage References
ADR290/ADR291/ADR292
a
PIN CONFIGURATIONS
8-Lead Narrow Body SO (SO Suffix)
FEATURES
Supply Range
2.35 V to 15 V, ADR290
2.8 V to 15 V, ADR291
4.4 V to 15 V, ADR292
Supply Current 12 A Max
Low-Noise 6 V, 8 V, 12 V p-p (0.1 Hz–10 Hz)
High Output Current 5 mA
Temperature Range 40C to 125C
Pin Compatible with REF02/REF19x
NC 1
VIN 2
8 NC
ADR29x
7 NC
TOP VIEW
NC 3 (Not to Scale) 6 VOUT
5 NC
GND 4
NC = NO CONNECT
8-Lead TSSOP (RU Suffix)
APPLICATIONS
Portable Instrumentation
Precision Reference for 3 V and 5 V Systems
A/D and D/A Converter Reference
Solar-Powered Applications
Loop-Current-Powered Instruments
NC 1
VIN 2
8 NC
ADR29x
7 NC
TOP VIEW
NC 3 (Not to Scale) 6 VOUT
GND 4
5 NC
NC = NO CONNECT
GENERAL DESCRIPTION
The ADR290, ADR291 and ADR292 are low noise, micropower precision voltage references that use an XFET® reference
circuit. The new XFET architecture offers significant performance improvements over traditional bandgap and Buried
Zener-based references. Improvements include: one quarter the
voltage noise output of bandgap references operating at the
same current, very low and ultralinear temperature drift, low
thermal hysteresis and excellent long-term stability.
The ADR29x family are series voltage references providing stable
and accurate output voltages from supplies as low as 2.35 V for the
ADR290. Output voltage options are 2.048 V, 2.5 V, and 4.096 V
for the ADR290, ADR291, and ADR292 respectively. Quiescent
current is only 12 µA, making these devices ideal for batterypowered instrumentation. Three electrical grades are available
offering initial output accuracies of ± 2 mV, ± 3 mV and ± 6 mV
max for the ADR290 and ADR291, and ± 3 mV, ± 4 mV and
± 6 mV max for the ADR292. Temperature coefficients for the
three grades are 8 ppm/°C, 15 ppm/°C, and 25 ppm/°C max,
respectively. Line regulation and load regulation are typically
30 ppm/V and 30 ppm/mA, maintaining the reference’s overall
high performance. For a device with 5.0 V output, refer to the
ADR293 data sheet.
The ADR290, ADR291, and ADR292 references are specified
over the extended industrial temperature range of –40°C to
+125°C. Devices are available in the 8-lead SOIC and 8-lead
TSSOP packages.
ADR29x Product
Part Number
Output Voltage
(V)
Initial Accuracy
(%)
Temperature Coefficient
(ppm/C) Max
ADR290
ADR291
ADR292
ADR293
2.048
2.500
4.096
5.000
0.10, 0.15, 0.29
8, 15, 25
0.08, 0.12, 0.24
8, 15, 25
0.07, 0.10, 0.15
8, 15, 25
(See ADR293 Data Sheet)
XFET is a registered trademark of Analog Devices, Inc.
REV. B
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
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 2001
ADR290/ADR291/ADR292
ADR290–SPECIFICATIONS
ELECTRICAL SPECIFICATIONS
(VS = 2.7 V, TA = +25C unless otherwise noted)
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
E GRADE
Output Voltage
Initial Accuracy
VO
VOERR
IOUT = 0 mA
2.046
–2
–0.10
2.048 2.050
+2
+0.10
V
mV
%
F GRADE
Output Voltage
Initial Accuracy
VO
VOERR
IOUT = 0 mA
2.045
–3
–0.15
2.048 2.051
+3
+0.15
V
mV
%
G GRADE
Output Voltage
Initial Accuracy
VO
VOERR
IOUT = 0 mA
2.042
–6
–0.29
2.048 2.054
+6
+0.29
V
mV
%
LINE REGULATION
“E/F” Grades
“G” Grade
∆VO/∆VIN
2.7 V to 15 V, IOUT = 0 mA
30
40
100
125
ppm/V
ppm/V
LOAD REGULATION
“E/F” Grades
“G” Grade
∆VO/∆ILOAD
VS = 5.0 V, 0 mA to 5 mA
30
40
100
125
ppm/mA
ppm/mA
LONG-TERM STABILITY
∆VO
After 1000 hrs of Operation @ 125°C
50
ppm
NOISE VOLTAGE
eN
0.1 Hz to 10 Hz
6
µV p-p
WIDEBAND NOISE DENSITY
eN
@ 1 kHz
420
nV/√Hz
ELECTRICAL SPECIFICATIONS (V = 2.7 V, T = –25C ≤ T ≤ +85C unless otherwise noted)
S
A
A
Parameter
Symbol
Conditions
TEMPERATURE COEFFICIENT
“E” Grade
“F” Grade
“G” Grade
TCVO
LINE REGULATION
“E/F” Grades
“G” Grade
LOAD REGULATION
“E/F” Grades
“G” Grade
Min
Typ
Max
Unit
IOUT = 0 mA
3
6
10
8
15
25
ppm/°C
ppm/°C
ppm/°C
∆VO/∆VIN
2.7 V to 15 V, IOUT = 0 mA
35
50
125
150
ppm/V
ppm/V
∆VO/∆ILOAD
VS = 5.0 V, 0 mA to 5 mA
20
30
125
150
ppm/mA
ppm/mA
Typ
Max
Unit
ELECTRICAL SPECIFICATIONS (V = 2.7 V, T = 40C ≤ T ≤ +125C unless otherwise noted)
S
A
A
Parameter
Symbol
Conditions
Min
TEMPERATURE COEFFICIENT
“E” Grade
“F” Grade
“G” Grade
TCVO
IOUT = 0 mA
3
5
10
10
20
30
ppm/°C
ppm/°C
ppm/°C
LINE REGULATION
“E/F” Grades
“G” Grade
∆VO/∆VIN
2.7 V to 15 V, IOUT = 0 mA
40
70
200
250
ppm/V
ppm/V
LOAD REGULATION
“E/F” Grades
“G” Grade
∆VO/∆ILOAD
VS = 5.0 V, 0 mA to 5 mA
20
30
200
300
ppm/mA
ppm/mA
SUPPLY CURRENT
IS
TA = +25°C
–40°C ≤ TA ≤ +125°C
8
12
12
15
µA
µA
THERMAL HYSTERESIS
VO–HYS
SO-8, TSSOP-8
50
ppm
Specifications subject to change without notice.
–2–
REV. B
ADR291–SPECIFICATIONS
ADR290/ADR291/ADR292
ELECTRICAL SPECIFICATIONS (V = 3.0 V, T = +25C unless otherwise noted)
S
A
Parameter
Symbol
Conditions
Min
Typ
E GRADE
Output Voltage
Initial Accuracy
VO
VOERR
IOUT = 0 mA
2.498
–2
–0.08
2.500 2.502
+2
+0.08
V
mV
%
F GRADE
Output Voltage
Initial Accuracy
VO
VOERR
IOUT = 0 mA
2.497
–3
–0.12
2.500 2.503
+3
+0.12
V
mV
%
G GRADE
Output Voltage
Initial Accuracy
VO
VOERR
IOUT = 0 mA
2.494
–6
–0.24
2.500 2.506
+6
+0.24
V
mV
%
LINE REGULATION
“E/F” Grades
“G” Grade
∆VO/∆VIN
3.0 V to 15 V, IOUT = 0 mA
30
40
100
125
ppm/V
ppm/V
LOAD REGULATION
“E/F“ Grades
“G“ Grade
∆VO/∆ILOAD
VS = 5.0 V, 0 mA to 5 mA
30
40
100
125
ppm/mA
ppm/mA
LONG-TERM STABILITY
∆VO
After 1000 hrs of Operation @ 125°C
50
ppm
NOISE VOLTAGE
eN
0.1 Hz to 10 Hz
8
µV p-p
WIDEBAND NOISE DENSITY
eN
@ 1 kHz
480
nV/√Hz
ELECTRICAL SPECIFICATIONS
Max
Unit
(VS = 3.0 V, TA = –25C ≤ TA ≤ +85C unless otherwise noted)
Parameter
Symbol
Conditions
TEMPERATURE COEFFICIENT
“E” Grade
“F” Grade
“G” Grade
TCVO
LINE REGULATION
“E/F” Grades
“G” Grade
LOAD REGULATION
“E/F” Grades
“G” Grade
Min
Typ
Max
Unit
IOUT = 0 mA
3
5
10
8
15
25
ppm/°C
ppm/°C
ppm/°C
∆VO/∆VIN
3.0 V to 15 V, IOUT = 0 mA
35
50
125
150
ppm/V
ppm/V
∆VO/∆ILOAD
VS = 5.0 V, 0 mA to 5 mA
20
30
125
150
ppm/mA
ppm/mA
Typ
Max
Unit
ELECTRICAL SPECIFICATIONS (V = 3.0 V, T = –40C ≤ T ≤ +125C unless otherwise noted)
S
A
A
Parameter
Symbol
Conditions
TEMPERATURE COEFFICIENT
“E” Grade
“F” Grade
“G” Grade
TCVO
IOUT = 0 mA
3
5
10
10
20
30
ppm/°C
ppm/°C
ppm/°C
LINE REGULATION
“E/F” Grades
“G” Grade
∆VO/∆VIN
3.0 V to 15 V, IOUT = 0 mA
40
70
200
250
ppm/V
ppm/V
LOAD REGULATION
“E/F” Grades
“G” Grade
∆VO/∆ILOAD
VS = 5.0 V, 0 mA to 5 mA
20
30
200
300
ppm/mA
ppm/mA
SUPPLY CURRENT
IS
TA = +25°C
–40°C ≤ TA ≤ +125°C
9
12
12
15
µA
µA
THERMAL HYSTERESIS
VO–HYS
SO-8, TSSOP-8
50
Specifications subject to change without notice.
REV. B
–3–
Min
ppm
ADR290/ADR291/ADR292
ADR292–SPECIFICATIONS
ELECTRICAL SPECIFICATIONS
(VS = 5 V, TA = +25C unless otherwise noted)
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
E GRADE
Output Voltage
Initial Accuracy
VO
VOERR
IOUT = 0 mA
4.093
–3
–0.07
4.096 4.099
+3
+0.07
V
mV
%
F GRADE
Output Voltage
Initial Accuracy
VO
VOERR
IOUT = 0 mA
4.092
–4
–0.10
4.096 4.1
+4
+0.10
V
mV
%
G GRADE
Output Voltage
Initial Accuracy
VO
VOERR
IOUT = 0 mA
4.090
–6
–0.15
4.096 4.102
+6
+0.15
V
mV
%
LINE REGULATION
“E/F” Grades
“G” Grade
∆VO/∆VIN
4.5 V to 15 V, IOUT = 0 mA
30
40
100
125
ppm/V
ppm/V
LOAD REGULATION
“E/F” Grades
“G” Grade
∆VO/∆ILOAD
VS = 5.0 V, 0 mA to 5 mA
30
40
100
125
ppm/mA
ppm/mA
LONG-TERM STABILITY
∆VO
After 1000 hrs of Operation @ 125°C
50
ppm
NOISE VOLTAGE
eN
0.1 Hz to 10 Hz
12
µV p-p
WIDEBAND NOISE DENSITY
eN
@ 1 kHz
640
nV/√Hz
ELECTRICAL SPECIFICATIONS (V = 5 V, T = –25C ≤ T ≤ +85C unless otherwise noted)
S
A
A
Parameter
Symbol
Conditions
TEMPERATURE COEFFICIENT
“E” Grade
“F” Grade
“G” Grade
TCVO
LINE REGULATION
“E/F” Grades
“G” Grade
LOAD REGULATION
“E/F” Grades
“G” Grade
Min
Typ
Max
Unit
IOUT = 0 mA
3
5
10
8
15
25
ppm/°C
ppm/°C
ppm/°C
∆VO/∆VIN
4.5 V to 15 V, IOUT = 0 mA
35
50
125
150
ppm/V
ppm/V
∆VO/∆ILOAD
VS = 5.0 V, 0 mA to 5 mA
20
30
125
150
ppm/mA
ppm/mA
Typ
Max
Unit
ELECTRICAL SPECIFICATIONS (V = 5 V, T = –40C ≤ T ≤ +125C unless otherwise noted)
S
A
A
Parameter
Symbol
Conditions
Min
TEMPERATURE COEFFICIENT
“E” Grade
“F” Grade
“G” Grade
TCVO
IOUT = 0 mA
3
5
10
10
20
30
ppm/°C
ppm/°C
ppm/°C
LINE REGULATION
“E/F” Grades
“G” Grade
∆VO/∆VIN
4.5 V to 15 V, IOUT = 0 mA
40
70
200
250
ppm/V
ppm/V
LOAD REGULATION
“E/F” Grades
“G” Grade
∆VO/∆ILOAD
VS = 5.0 V, 0 mA to 5 mA
20
30
200
300
ppm/mA
ppm/mA
SUPPLY CURRENT
IS
TA = +25°C
–40°C ≤ TA ≤ +125°C
10
12
15
18
µA
µA
THERMAL HYSTERESIS
VO–HYS
SO-8, TSSOP-8
50
ppm
Specifications subject to change without notice.
–4–
REV. B
ADR290/ADR291/ADR292
ABSOLUTE MAXIMUM RATINGS
Supply Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 V
Output Short-Circuit Duration to GND . . . . . . . . . . Indefinite
Storage Temperature Range
SO, RU Package . . . . . . . . . . . . . . . . . . . ⫺65°C to 150°C
Operating Temperature Range
ADR290/ADR291/ADR292 . . . . . . . . . . . ⫺40°C to 125°C
Junction Temperature Range
SO, RU Package . . . . . . . . . . . . . . . . . . . ⫺65°C to 125°C
Lead Temperature (Soldering, 60 sec) . . . . . . . . . . . . . 300°C
Package Type
JA*
JC
Unit
8-Lead SOIC (SO)
8-Lead TSSOP (RU)
158
240
43
43
°C/W
°C/W
*θJA is specified for worst-case conditions, i.e., θJA is specified for device in socket
testing. In practice, θJA is specified for a device soldered in the circuit board.
NOTES
1. Stresses above those listed under Absolute Maximum Ratings may
cause permanent damage to the device. This is a stress rating only; functional
operation at or above this specification is not implied. Exposure to the
above maximum rating conditions for extended periods may affect device
reliability.
2. Remove power before inserting or removing units from their sockets.
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 the ADR290/ADR291/ADR292 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.
WARNING!
ESD SENSITIVE DEVICE
ORDERING GUIDE
Model
Output
Voltage
Initial
Accuracy (%)
Temperature
Coefficient
Max (ppm/C)
Package
Description
Package
Option
Number of
Parts per
Package
ADR290
ER, ER-REEL7, ER-REEL
FR, FR-REEL7, FR-REEL
GR, GR-REEL7, GR-REEL
GRU-REEL7, GRU-REEL
2.048
2.048
2.048
2.048
0.10
0.15
0.29
0.29
8
15
25
25
SOIC
SOIC
SOIC
TSSOP
SO-8
SO-8
SO-8
RU-8
98, 1000, 2500
98, 1000, 2500
98, 1000, 2500
1000, 2500
ADR291
ER, ER-REEL7, ER-REEL
FR, FR-REEL7, FR-REEL
GR, GR-REEL7, GR-REEL
GRU-REEL7, GRU-REEL
2.50
2.50
2.50
2.50
0.08
0.12
0.24
0.24
8
15
25
25
SOIC
SOIC
SOIC
TSSOP
SO-8
SO-8
SO-8
RU-8
98, 1000, 2500
98, 1000, 2500
98, 1000, 2500
1000, 2500
ADR292
ER, ER-REEL7, ER-REEL
FR, FR-REEL7, FR-REEL
GR, GR-REEL7, GR-REEL
GRU-REEL7, GRU-REEL
4.096
4.096
4.096
4.096
0.07
0.10
0.15
0.15
8
15
25
25
SOIC
SOIC
SOIC
TSSOP
SO-8
SO-8
SO-8
RU-8
98, 1000, 2500
98, 1000, 2500
98, 1000, 2500
1000, 2500
See ADR293 data sheet for ordering guide.
OTHER XFET PRODUCTS
Part
Number
Nominal Output
Voltage (V)
Package
Type
ADR420
ADR421
2.048
2.50
8-Lead_µSOIC/SOIC
8-Lead_µSOIC/SOIC
REV. B
–5–
ADR290/ADR291/ADR292
PARAMETER DEFINITION
Thermal Hysteresis
Line Regulation
Thermal hysteresis is defined as the change of output voltage after the device is cycled through temperature from +25°C to
–40°C to +85°C and back to +25°C. This is a typical value from
a sample of parts put through such a cycle.
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-pervolt, or microvolts-per-volt change in input voltage.
VO – HYS = VO (25°C ) – VO _ TC
Load Regulation
VO – HYS [ ppm] =
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-permillion-per-milliampere, or ohms of dc output resistance.
VO (25°C ) – VO _ TC
× 106
VO (25°C )
Where
VO (25°C) = VO at 25°C
Long-Term Stability
VO–TC = VO at 25°C after temperature cycle at +25°C to
–40°C to +85°C and back to +25°C
Typical shift of output voltage at 25°C on a sample of parts
subjected to high-temperature operating life test of 1000
hours at 125°C.
∆VO = VO (t0 ) – VO (t1 )
V (t ) – VO (t1 )
∆VO [ ppm] = O 0
× 106
VO (t0 )
Where
VO (t0 ) = VO at 25°C at time 0
VO (t1 ) = VO at 25°C after 1000 hours operation at 125°C
Temperature Coefficient
The change of output voltage over the operating temperature
change and normalized by the output voltage at 25°C, expressed
in ppm/°C. The equation follows:
TCVO [ ppm / °C ] =
VO (T2 ) – VO (T1 )
× 106
VO (25°C ) × (T2 – T1 )
Where
VO (25°C) = VO at 25°C
VO(T1 ) = VO at Temperature 1
VO(T2 ) = VO at Temperature 2
NC = No Connect
(There are in fact internal connections at NC pins which are
reserved for manufacturing purposes. Users should not connect
anything at NC pins.)
–6–
REV. B
Typical Performance Characteristic–ADR290/ADR291/ADR292
14
2.054
VS = 5V
3 TYPICAL PARTS
12
QUIESCENT CURRENT – A
OUTPUT VOLTAGE – V
2.052
2.050
2.048
2.046
2.044
10
TA = +125C
8
TA = +25C
TA = –40C
6
4
2
2.042
–50
–25
0
25
50
75
100
0
125
0
2
4
TEMPERATURE – C
TPC 1. ADR290 VOUT vs. Temperature
12
14
16
TPC 4. ADR290 Quiescent Current vs. Input Voltage
14
2.506
VS = 5V
3 TYPICAL PARTS
12
QUIESCENT CURRENT – A
2.504
OUTPUT VOLTAGE – V
6
8
10
INPUT VOLTAGE – V
2.502
2.500
2.498
2.496
TA = +125C
10
TA = +25C
8
TA = –40C
6
4
2
2.494
–50
–25
0
25
50
75
100
0
125
0
2
4
TEMPERATURE – C
TPC 2. ADR291 VOUT vs. Temperature
6
8
10
INPUT VOLTAGE – V
12
14
16
TPC 5. ADR291 Quiescent Current vs. Input Voltage
16
4.102
VS = 5V
3 TYPICAL PARTS
14
QUIESCENT CURRENT – A
OUTPUT VOLTAGE – V
4.100
4.098
4.096
4.094
4.092
TA = +125C
10
TA = +25C
TA = –40C
8
6
4
2
4.090
–50
–25
0
25
50
75
100
0
125
TEMPERATURE – C
TPC 3. ADR292 VOUT vs. Temperature
REV. B
12
0
2
4
6
8
10
INPUT VOLTAGE – V
12
14
16
TPC 6. ADR292 Quiescent Current vs. Input Voltage
–7–
ADR290/ADR291/ADR292
14
0.7
VS = 5V
0.6
ADR291
ADR292
DIFFERENTIAL VOLTAGE – V
SUPPLY CURRENT – A
12
10
8
ADR290
6
TA = –40C
0.5
TA = +125C
0.4
0.3
TA = +25C
0.2
0.1
4
–50
–25
0
25
50
75
100
0
125
0
0.5
1.0
1.5
TEMPERATURE – C
100
5.0
IOUT = 0mA
0.6
80
DIFFERENTIAL VOLTAGE – V
LINE REGULATION – ppm/V
4.5
0.7
ADR290: VS = 2.7V TO 15V
ADR291: VS = 3.0V TO 15V
ADR292: VS = 4.5V TO 15V
60
ADR292
40
20
ADR290
–25
0
25
50
75
100
TA = +125C
0.5
TA = +25C
0.4
0.3
TA = –40C
0.2
0.1
ADR291
0
125
0
0.5
1.0
1.5
TEMPERATURE – C
TPC 8. ADR290/ADR291/ADR292 Line Regulation vs.
Temperature
2.0
2.5
3.0 3.5
LOAD CURRENT – mA
4.0
4.5
5.0
TPC 11. ADR291 Minimum Input-Output Voltage
Differential vs. Load Current
100
0.7
ADR290: VS = 2.7V TO 7.0V
ADR291: VS = 3.0V TO 7.0V
ADR292: VS = 4.5V TO 9.0V
IOUT = 0mA
0.6
80
DIFFERENTIAL VOLTAGE – V
LINE REGULATION – ppm/V
4.0
TPC 10. ADR290 Minimum Input-Output Voltage
Differential vs. Load Current
TPC 7. ADR290/ADR291/ADR292 Supply Current vs.
Temperature
0
–50
2.0
2.5
3.0 3.5
LOAD CURRENT – mA
60
ADR290
ADR291
40
ADR292
20
TA = +125C
0.5
TA = +25C
0.4
0.3
TA = –40C
0.2
0.1
0
–50
–25
0
25
50
75
100
0
125
0
TEMPERATURE – C
0.5
1.0
1.5
2.0
2.5
3.0 3.5
LOAD CURRENT – mA
4.0
4.5
5.0
TPC 12. ADR292 Minimum Input-Output Voltage
Differential vs. Load Current
TPC 9. ADR290/ADR291/ADR292 Line Regulation vs.
Temperature
–8–
REV. B
ADR290/ADR291/ADR292
200
500
250
160
VOUT FROM NOMINAL – V
LINE REGULATION – ppm/mA
VS = 5V
120
IOUT = 1mA
80
40
0
–25
25
50
75
100
TEMPERATURE – C
TA = –40C
1
SOURCING LOAD CURRENT – mA
10
TPC 16. ADR290 ∆VOUT from Nominal vs. Load Current
TPC 13. ADR290 Line Regulation vs. Temperature
200
0
VS = 5V
–250
160
VOUT FROM NOMINAL – V
LOAD REGULATION – ppm/mA
TA = +125C
–500
–1000
0.1
125
TA = +25C
–250
–750
IOUT = 5mA
0
–50
0
IOUT = 1mA
120
IOUT = 5mA
80
40
TA = +25C
–500
–750
TA = –40C
–1000
TA = +125C
–1250
–1500
–1750
0
–50
0
–25
25
50
75
100
–2000
0.1
125
TEMPERATURE – C
10
TPC 17. ADR291 ∆VOUT from Nominal vs. Load Current
TPC 14. ADR291 Load Regulation vs. Temperature
200
0
VS = 5V
–500
160
VOUT FROM NOMINAL – V
LOAD REGULATION – ppm/mA
1
SOURCING LOAD CURRENT – mA
120
IOUT = 1mA
IOUT = 5mA
80
40
–1000
–1500
–2000
TA = +25C
TA = –40C
TA = +125C
–2500
–3000
–3500
0
–50
–25
0
25
50
75
100
–4000
0.1
125
TEMPERATURE – C
10
TPC 18. ADR292 ∆VOUT from Nominal vs. Load Current
TPC 15. ADR292 Load Regulation vs. Temperature
REV. B
1
SOURCING LOAD CURRENT – mA
–9–
ADR290/ADR291/ADR292
1000
50
ADR292
VOLTAGE NOISE DENSITY – nV/冪Hz
900
VS = 5V
IL = 0 mA
VIN = 15V
TA = 25C
800
OUTPUT IMPEDANCE – 40
700
ADR291
600
500
400
300
ADR290
200
30
20
10
100
0
10
100
FREQUENCY – Hz
0
1000
TPC 19. Voltage Noise Density vs. Frequency
0
100
FREQUENCY – Hz
1k
10k
TPC 22. ADR290 Output Impedance vs. Frequency
50
120
VS = 5V
IL = 0 mA
VS = 5V
100
40
OUTPUT IMPEDANCE – RIPPLE REJECTION – dB
10
80
60
40
30
20
10
20
0
10
100
FREQUENCY – Hz
0
1000
TPC 20. ADR290/ADR291/ADR292 Ripple Rejection vs.
Frequency
0
10
100
FREQUENCY – Hz
1k
10k
TPC 23. ADR291 Output Impedance vs. Frequency
50
VS = 5V
IL = 0 mA
1s
40
OUTPUT IMPEDANCE – 100
90
2V p-p
10
0%
30
20
10
0
TPC 21. ADR290 0.1 Hz to 10 Hz Noise
0
10
100
FREQUENCY – Hz
1k
10k
TPC 24. ADR292 Output Impedance vs. Frequency
–10–
REV. B
ADR290/ADR291/ADR292
IL = 5mA
1ms
500s
IL = 5mA
OFF
ON
100
100
90
90
10
10
0%
0%
1V
1V
TPC 25. ADR291 Load Transient
IL = 5mA
CL = 1nF
OFF
TPC 28. ADR291 Turn-On Time
1ms
IL = 0mA
100
100
90
90
10ms
ON
10
10
0%
0%
1V
1V
TPC 26. ADR291 Load Transient
TPC 29. ADR291 Turn-Off Time
18
IL = 5mA
CL = 100nF
5ms
16
14
100
OFF
TEMPERATURE
+25C –40C
85C +25C
90
FREQUENCY
12
ON
10
8
6
10
4
0%
0
–200
–180
–160
–140
–120
–100
–80
–60
–40
–20
0
20
40
60
80
100
120
140
160
180
200
MORE
2
1V
VOUT DEVIATION – ppm
TPC 27. ADR291 Load Transient
REV. B
TPC 30. Typical Hysteresis for the ADR291 Product
–11–
ADR290/ADR291/ADR292
THEORY OF OPERATION
Device Power Dissipation Considerations
The ADR29x series of references uses a new reference generation
technique known as XFET (eXtra implanted junction FET). This
technique yields a reference with low noise, low supply current
and very low thermal hysteresis.
The ADR29x family of references is guaranteed to deliver load
currents to 5 mA with an input voltage that ranges from 2.7 V
to 15 V (minimum supply voltage depends on output voltage
option). When these devices are used in applications with large
input voltages, care should be exercised to avoid exceeding the
published specifications for maximum power dissipation or junction temperature that could result in premature device failure.
The following formula should be used to calculate a device’s maximum junction temperature or dissipation:
The core of the XFET reference consists of two junction fieldeffect transistors, 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/K. This slope is
essentially locked 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 bandgap references. The big advantage
over a bandgap reference is that the intrinsic temperature coefficient is some thirty times lower (therefore less correction is
needed) and this results in much lower noise since most of the
noise of a bandgap reference comes from the temperature compensation circuitry.
The simplified schematic below shows the basic topology of the
ADR29x series. The temperature correction term is provided by
a current source with value designed to be proportional to absolute temperature. The general equation is:
PD =
In this equation, TJ and TA are the junction and ambient temperatures, respectively, PD is the device power dissipation, and
θJA is the device package thermal resistance.
Basic Voltage Reference Connections
References, in general, require a bypass capacitor connected
from the VOUT pin to the GND pin. The circuit in Figure 2
illustrates the basic configuration for the ADR29x family of references. Note that the decoupling capacitors are not required for
circuit stability.
NC 1
2
VOUT
 R1 + R2 + R3 
= ∆VP 
 + I PTAT R3
R1


(
)( )
10F
VIN
I1
8 NC
ADR29x
7 NC
6
OUTPUT
0.1F
0.1F
4
The process used for the XFET reference also features vertical
NPN and PNP transistors, the latter of which are used as output
devices to provide a very low drop-out voltage.
I1
NC 3
+
where ∆VP is the difference in pinch-off voltage between the two
FETs, and IPTAT is the positive temperature coefficient correction current. The various versions of the ADR29x family are
created by on-chip adjustment of R1 and R3 to achieve 2.048 V,
2.500 V or 4.096 V at the reference output.
TJ – T A
θ JA
5 NC
NC = NO CONNECT
Figure 2. Basic Voltage Reference Configuration
Noise Performance
The noise generated by the ADR29x family of references is typically less than 12 µV p-p over the 0.1 Hz to 10 Hz band. TPC
21 shows the 0.1 Hz to 10 Hz noise of the ADR290 which is only
6 µV p-p. The noise measurement is made with a bandpass 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
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. TPC 28 shows the turn-on settling time for the ADR291.
VOUT
R1
IPTAT
R2
R3
GND
* EXTRA CHANNEL IMPLANT
R1 + R2 + R3
VOUT =
VP + IPTAT
R1
R3
Figure 1. ADR290/ADR291/ADR292 Simplified Schematic
–12–
REV. B
ADR290/ADR291/ADR292
APPLICATIONS SECTION
A Negative Precision Reference without Precision Resistors
VIN
In many current-output CMOS DAC applications, where the
output signal voltage must be of the same polarity as the reference
voltage, it is often required to reconfigure a current-switching
DAC into a voltage-switching DAC through the use of a 1.25 V
reference, an op amp and a pair of resistors. Using a currentswitching DAC directly requires the need for an additional
operational amplifier at the output to reinvert the signal. A
negative voltage reference is then desirable from the point that
an additional operational amplifier is not required for either
reinversion (current-switching mode) or amplification (voltageswitching mode) of the DAC output voltage. In general, any
positive voltage reference can be converted into a negative voltage reference through the use of an operational amplifier and a
pair of matched resistors in an inverting configuration. The disadvantage to that approach is that the largest single source of
error in the circuit is the relative matching of the resistors used.
The circuit illustrated in Figure 3 avoids the need for tightly
matched resistors with the use of an active integrator circuit. In
this circuit, the output of the voltage reference provides the
input drive for the integrator. The integrator, to maintain circuit
equilibrium adjusts its output to establish the proper relationship
between the reference’s VOUT and GND. Thus, any negative
output voltage desired can be chosen by simply substituting for
the appropriate reference IC. One caveat with this approach
should be mentioned: although rail-to-rail output amplifiers
work best in the application, these operational amplifiers require
a finite amount (mV) of headroom when required to provide
any load current. The choice for the circuit’s negative supply
should take this issue into account.
ADR29x
VOUT
R1
GND
1F
RSET
ISY
ADJUST
P1
IOUT
RL
Figure 4. A Precision Current Source
High Voltage Floating Current Source
The circuit of Figure 5 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.
+VS
E231
SILICONIX
VIN
ADR29X
VIN
OP90
2N3904
GND
2.10k
ADR29x
1k
VOUT
–VS
1F
Figure 5. High Voltage Floating Current Source
+5V
Kelvin Connections
GND
100k
1F
100
A1
–VREF
–5V
A1 = 1/2 OP291,
1/2 OP295
Figure 3. A Negative Precision Voltage Reference Uses No
Precision Resistors
A Precision Current Source
Many times in low power applications, the need arises for a precision current source that can operate on low supply voltages.
As shown in Figure 4, any one of the devices in the ADR29x
family of references can be configured as a precision current
source. The circuit configuration illustrated is a floating current
source with a grounded load. The reference’s output voltage is
bootstrapped across RSET, which sets the output current into the
load. With this configuration, circuit precision is maintained for
load currents in the range from the reference’s supply current,
typically 12 µA to approximately 5 mA.
REV. B
In many portable instrumentation applications, where PC board
cost and area go hand-in-hand, circuit interconnects are very often
of dimensionally minimum width. 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 of Figure 6, overcomes
the problem by including the wiring resistance within the forcing
loop of the op amp. Since 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.
–13–
ADR290/ADR291/ADR292
VIN
Voltage Regulator For Portable Equipment
RLW
VIN
ADR29x
The ADR29x family of references is ideal for providing a stable,
low cost and low power reference voltage in portable equipment
power supplies. Figure 8 shows how the ADR290/ADR291/
ADR292 can be used in a voltage regulator that not only has
low output noise (as compared to switch mode design) and
low power, but also a very fast recovery after current surges.
Some precautions should be taken in the selection of the output capacitors. Too high an ESR (Effective Series Resistance)
could endanger the stability of the circuit. A solid tantalum
capacitor, 16 V or higher, and an aluminum electrolytic capacitor,
10 V or higher, are recommended for C1 and C2, respectively.
Also, the path from the ground side of C1 and C2 to the ground
side of R1 should be kept as short as possible.
+VOUT
SENSE
RLW
A1
VOUT
+VOUT
FORCE
RL
1F
100k
GND
A1 = 1/2 OP295
Figure 6. Advantage of Kelvin Connection
Low Power, Low Voltage Reference For Data Converters
The ADR29x family has a number of features that makes it
ideally suited for use with A/D and D/A converters. The low
supply voltage required makes it possible to use the ADR290
and ADR291 with today’s converters that run on 3 V supplies
without having to add a higher supply voltage for the reference.
The low quiescent current (12 µA max) and low noise, tight
temperature coefficient, combined with the high accuracy of
the ADR29x makes it ideal for low power applications such
as hand-held, battery operated equipment.
One such ADC for which the ADR291 is well suited is the
AD7701. Figure 7 shows the ADR291 used as the reference for
this converter. The AD7701 is a 16-bit A/D converter with onchip digital filtering intended for the measurement of wide
dynamic range, low frequency signals such as those representing
chemical, physical or biological processes. It contains a charge
balancing (sigma-delta) ADC, calibration microcontroller with
on-chip static RAM, a clock oscillator and a serial communications port.
CHARGER
INPUT
0.1F
R3
510k
VIN
ADR29x
6V
LEAD-ACID
BATTERY
+
VOUT
TEMP
GND
OP20
IRF9530
5V, 100mA
R1
402k
1%
R2
402k
1%
C1
68F
TANT
+
+ C2
1000F
ELECT
Figure 8. Voltage Regulator for Portable Equipment
This entire circuit runs on ± 5 V supplies. The power dissipation
of the AD7701 is typically 25 mW and, when combined with
the power dissipation of the ADR291 (60 µW), the entire circuit
still consumes about 25 mW.
+5V
ANALOG
SUPPLY
10F
0.1F
AVDD
0.1F
VIN
VOUT
DVDD
VREF
SLEEP
ADR291
GND
DRDY
AD7701
RANGES
SELECT
BP/UP
CS
DATA READY
READ (TRANSMIT)
SCLK
SERIAL CLOCK
SDATA
SERIAL CLOCK
CAL
CALIBRATE
CLKIN
ANALOG
INPUT
AIN
ANALOG
GROUND
AGND
0.1F
0.1F
CLKOUT
SC1
SC2
DGND
AVSS
–5V
ANALOG
SUPPLY
0.1F
MODE
0.1F
DVSS
10F
Figure 7. Low Power, Low Voltage Supply Reference for
the AD7701
–14–
REV. B
ADR290/ADR291/ADR292
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
0.1968 (5.00)
0.1890 (4.80)
0.1574 (4.00)
0.1497 (3.80)
8
5
1
4
0.2440 (6.20)
0.2284 (5.80)
PIN 1
0.0196 (0.50)
0.0099 (0.25)
0.0500 (1.27)
BSC
45
C00163–0–3/01 (B)
8-Lead Narrow Body SO (SO Suffix)
0.0688 (1.75)
0.0532 (1.35)
0.0098 (0.25)
0.0040 (0.10)
8
0.0500 (1.27)
0.0098 (0.25) 0
0.0160 (0.41)
0.0075 (0.19)
0.0192 (0.49)
0.0138 (0.35)
SEATING
PLANE
8-Lead TSSOP (RU Suffix)
0.122 (3.10)
0.114 (2.90)
8
5
0.177 (4.50)
0.169 (4.30)
0.256 (6.50)
0.246 (6.25)
1
4
PIN 1
0.0256 (0.65)
BSC
0.006 (0.15)
0.002 (0.05)
0.0118 (0.30)
0.0075 (0.19)
0.0079 (0.20)
0.0035 (0.090)
8
0
0.028 (0.70)
0.020 (0.50)
PRINTED IN U.S.A.
SEATING
PLANE
0.0433
(1.10)
MAX
REV. B
–15–