Ultralow Noise XFET Voltage References with Current Sink and Source Capability
ADR430/ADR431/ADR433/ADR434/ADR435/ADR439
FEATURES
Low noise (0.1 Hz to 10.0 Hz): 3.5 μV p-p @ 2.5 V output No external capacitor required Low temperature coefficient A Grade: 10 ppm/°C maximum B Grade: 3 ppm/°C maximum Load regulation: 15 ppm/mA Line regulation: 20 ppm/V Wide operating range ADR430: 4.1 V to 18 V ADR431: 4.5 V to 18 V ADR433: 5.0 V to 18 V ADR434: 6.1 V to 18 V ADR435: 7.0 V to 18 V ADR439: 6.5 V to 18 V High output source and sink current: +30 mA and −20 mA Wide temperature range: −40°C to +125°C
PIN CONFIGURATIONS
TP 1 VIN 2
8
TP
COMP TOP VIEW 6 VOUT (Not to Scale) GND 4 5 TRIM
7
ADR43x
NIC 3
Figure 1. 8-Lead MSOP (RM-8)
TP 1 VIN 2
8
TP
COMP TOP VIEW 6 VOUT (Not to Scale) 5 TRIM GND 4
7
ADR43x
NIC 3
Figure 2. 8-Lead SOIC_N (R-8)
APPLICATIONS
Precision data acquisition systems High resolution data converters Medical instruments Industrial process control systems Optical control circuits Precision instruments
GENERAL DESCRIPTION
The ADR43x series is a family of XFET® voltage references featuring low 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 ADR43x is minimized. The XFET references operate at lower current (800 μA) and lower supply voltage headroom (2 V) than buried Zener references. Buried Zener references require more than 5 V headroom for operation. The ADR43x XFET references are the only low noise solutions for 5 V systems. The ADR43x family has the capability to source up to 30 mA of output current and sink up to 20 mA. It also comes with a trim terminal to adjust the output voltage over a 0.5% range without compromising performance. The ADR43x is available in 8-lead MSOP and 8-lead narrow SOIC packages. All versions are specified over the extended industrial temperature range of −40°C to +125°C.
Rev. J
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.
Table 1. Selection Guide
Output Voltage (V) 2.048 2.048 2.500 2.500 3.000 3.000 4.096 4.096 5.000 5.000 4.500 4.500 Temperature Coefficient (ppm/°C) 10 3 10 3 10 3 10 3 10 3 10 3
Model ADR430A ADR430B ADR431A ADR431B ADR433A ADR433B ADR434A ADR434B ADR435A ADR435B ADR439A ADR439B
Accuracy (mV) ±3 ±1 ±3 ±1 ±4 ±1.5 ±5 ±1.5 ±6 ±2 ±5.5 ±2
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 ©2003–2011 Analog Devices, Inc. All rights reserved.
04500-041
NOTES 1. NIC = NO INTERNAL CONNECTION 2. TP = TEST PIN (DO NOT CONNECT)
04500-001
NOTES 1. NIC = NO INTERNAL CONNECTION 2. TP = TEST PIN (DO NOT CONNECT)
ADR430/ADR431/ADR433/ADR434/ADR435/ADR439 TABLE OF CONTENTS
Features .............................................................................................. 1 Applications....................................................................................... 1 Pin Configurations ........................................................................... 1 General Description ......................................................................... 1 Revision History ............................................................................... 3 Specifications..................................................................................... 4 ADR430 Electrical Characteristics............................................. 4 ADR431 Electrical Characteristics............................................. 5 ADR433 Electrical Characteristics............................................. 6 ADR434 Electrical Characteristics............................................. 7 ADR435 Electrical Characteristics............................................. 8 ADR439 Electrical Characteristics............................................. 9 Absolute Maximum Ratings.......................................................... 10 Thermal Resistance .................................................................... 10 ESD Caution................................................................................ 10 Typical Performance Characteristics ........................................... 11 Theory of Operation ...................................................................... 16 Basic Voltage Reference Connections...................................... 16 Noise Performance ..................................................................... 16 High Frequency Noise ............................................................... 16 Turn-On Time ............................................................................ 17 Applications Information .............................................................. 18 Output Adjustment .................................................................... 18 Reference for Converters in Optical Network Control Circuits......................................................................................... 18 High Voltage Floating Current Source .................................... 18 Kelvin Connection ..................................................................... 18 Dual Polarity References ........................................................... 19 Programmable Current Source ................................................ 19 Programmable DAC Reference Voltage .................................. 20 Precision Voltage Reference for Data Converters.................. 20 Precision Boosted Output Regulator ....................................... 21 Outline Dimensions ....................................................................... 22 Ordering Guide .......................................................................... 23
Rev. J | Page 2 of 24
ADR430/ADR431/ADR433/ADR434/ADR435/ADR439
REVISION HISTORY
7/11—Rev. I to Rev. J Changes to Figure 1 and Figure 2....................................................1 Changes to Ordering Guide...........................................................23 5/11—Rev. H to Rev. I Added Endnote 1 in Table 2.............................................................4 Added Endnote 1 in Table 3.............................................................5 Added Endnote 1 in Table 4.............................................................6 Added Endnote 1 in Table 5.............................................................7 Added Endnote 1 in Table 6.............................................................8 Added Endnote 1 in Table 7.............................................................9 Deleted Negative Precision Reference Without Precision Resistors Section..............................................................................17 Deleted Figure 36; Renumbered Sequentially .............................18 2/11—Rev. G to Rev. H Updated Outline Dimensions........................................................21 Changes to Ordering Guide...........................................................22 7/10—Rev. F to Rev. G Changes to Storage Temperature Range in Table 9.......................9 6/10—Rev. E to Rev. F Updated Pin Name NC to COMP Throughout ............................1 Changes to Figure 1 and Figure 2....................................................1 Changes to Figure 30 and High Frequency Noise Section ........15 Updated Outline Dimensions........................................................21 Changes to Ordering Guide...........................................................22 1/09—Rev. D to Rev. E Added High Frequency Noise Section and Equation 3; Renumbered Sequentially ..............................................................15 Inserted Figure 31, Figure 32, and Figure 33; Renumbered Sequentially ......................................................................................16 Changes to the Ordering Guide ....................................................22 12/07—Rev. C to Rev. D Changes to Initial Accuracy and Ripple Rejection Ratio Parameters in Table 2 through Table 7...........................................3 Changes to Table 9 ............................................................................9 Changes to Theory of Operation Section ....................................15 Updated Outline Dimensions........................................................20 8/06—Rev. B to Rev. C Updated Format ................................................................. Universal Changes to Table 1 ............................................................................1 Changes to Table 3 ............................................................................4 Changes to Table 4 ............................................................................5 Changes to Table 7 ............................................................................8 Changes to Figure 26 ......................................................................14 Changes to Figure 31 ......................................................................16 Updated Outline Dimensions........................................................20 Changes to Ordering Guide...........................................................21 9/04—Rev. A to Rev. B Added New Grade.............................................................. Universal Changes to Specifications ................................................................3 Replaced Figure 3, Figure 4, Figure 5 ...........................................10 Updated Ordering Guide ...............................................................21 6/04—Rev. 0 to Rev. A Changes to Format............................................................. Universal Changes to the Ordering Guide ....................................................20 12/03—Revision 0: Initial Version
Rev. J | Page 3 of 24
ADR430/ADR431/ADR433/ADR434/ADR435/ADR439 SPECIFICATIONS
ADR430 ELECTRICAL CHARACTERISTICS
VIN = 4.1 V to 18 V, IL = 0 mA, TA = 25°C, unless otherwise noted. Table 2.
Parameter OUTPUT VOLTAGE A Grade B Grade INITIAL ACCURACY 1 A Grade B Grade TEMPERATURE COEFFICIENT A Grade B Grade LINE REGULATION LOAD REGULATION QUIESCENT CURRENT VOLTAGE NOISE VOLTAGE NOISE DENSITY TURN-ON SETTLING TIME LONG-TERM STABILITY 2 OUTPUT VOLTAGE HYSTERESIS RIPPLE REJECTION RATIO SHORT CIRCUIT TO GND SUPPLY VOLTAGE OPERATING RANGE SUPPLY VOLTAGE HEADROOM
1 2
Symbol VO
Conditions
Min 2.045 2.047
Typ 2.048 2.048
Max 2.051 2.049 ±3 ±0.15 ±1 ±0.05
Unit V V mV % mV % ppm/°C ppm/°C ppm/V ppm/mA ppm/mA μA μV p-p nV/√Hz μs ppm ppm dB mA V V
VOERR
TCVO −40°C < TA < +125°C −40°C < TA < +125°C VIN = 4.1 V to 18 V, −40°C < TA < +125°C IL = 0 mA to 10 mA, VIN = 5.0 V, −40°C < TA < +125°C IL = −10 mA to 0 mA, VIN = 5.0 V, −40°C < TA < +125°C No load, −40°C < TA < +125°C 0.1 Hz to 10.0 Hz 1 kHz CL = 0 μF 1000 hours fIN = 1 kHz 2 1 5 10 3 20 15 15 800
∆VO/∆VIN ∆VO/∆IL ∆VO/∆IL IIN eN p-p eN tR ∆VO VO_HYS RRR ISC VIN VIN − VO
560 3.5 60 10 40 20 –70 40 4.1 2
18
Initial accuracy does not include shift due to solder heat effect. The long-term stability specification is noncumulative. The drift in subsequent 1000 hour periods is significantly lower than in the first 1000 hour period.
Rev. J | Page 4 of 24
ADR430/ADR431/ADR433/ADR434/ADR435/ADR439
ADR431 ELECTRICAL CHARACTERISTICS
VIN = 4.5 V to 18 V, IL = 0 mA, TA = 25°C, unless otherwise noted. Table 3.
Parameter OUTPUT VOLTAGE A Grade B Grade INITIAL ACCURACY 1 A Grade B Grade TEMPERATURE COEFFICIENT A Grade B Grade LINE REGULATION LOAD REGULATION QUIESCENT CURRENT VOLTAGE NOISE VOLTAGE NOISE DENSITY TURN-ON SETTLING TIME LONG-TERM STABILITY 2 OUTPUT VOLTAGE HYSTERESIS RIPPLE REJECTION RATIO SHORT CIRCUIT TO GND SUPPLY VOLTAGE OPERATING RANGE SUPPLY VOLTAGE HEADROOM
1 2
Symbol VO
Conditions
Min 2.497 2.499
Typ 2.500 2.500
Max 2.503 2.501 ±3 ±0.12 ±1 ±0.04
Unit V V mV % mV % ppm/°C ppm/°C ppm/V ppm/mA ppm/mA μA μV p-p nV/√Hz μs ppm ppm dB mA V V
VOERR
TCVO −40°C < TA < +125°C −40°C < TA < +125°C VIN = 4.5 V to 18 V, −40°C < TA < +125°C IL = 0 mA to 10 mA, VIN = 5.0 V, −40°C < TA < +125°C IL = −10 mA to 0 mA, VIN = 5.0 V, −40°C < TA < +125°C No load, −40°C < TA < +125°C 0.1 Hz to 10.0 Hz 1 kHz CL = 0 μF 1000 hours fIN = 1 kHz 2 1 5 10 3 20 15 15 800
∆VO/∆VIN ∆VO/∆IL ∆VO/∆IL IIN eN p-p eN tR ∆VO VO_HYS RRR ISC VIN VIN − VO
580 3.5 80 10 40 20 −70 40 4.5 2
18
Initial accuracy does not include shift due to solder heat effect. The long-term stability specification is noncumulative. The drift in subsequent 1000 hour periods is significantly lower than in the first 1000 hour period.
Rev. J | Page 5 of 24
ADR430/ADR431/ADR433/ADR434/ADR435/ADR439
ADR433 ELECTRICAL CHARACTERISTICS
VIN = 5.0 V to 18 V, IL = 0 mA, TA = 25°C, unless otherwise noted. Table 4.
Parameter OUTPUT VOLTAGE A Grade B Grade INITIAL ACCURACY 1 A Grade B Grade TEMPERATURE COEFFICIENT A Grade B Grade LINE REGULATION LOAD REGULATION QUIESCENT CURRENT VOLTAGE NOISE VOLTAGE NOISE DENSITY TURN-ON SETTLING TIME LONG-TERM STABILITY 2 OUTPUT VOLTAGE HYSTERESIS RIPPLE REJECTION RATIO SHORT CIRCUIT TO GND SUPPLY VOLTAGE OPERATING RANGE SUPPLY VOLTAGE HEADROOM
1 2
Symbol VO
Conditions
Min 2.996 2.9985
Typ 3.000 3.000
Max 3.004 3.0015 ±4 ±0.13 ±1.5 ±0.05
Unit V V mV % mV % ppm/°C ppm/°C ppm/V ppm/mA ppm/mA μA μV p-p nV/√Hz μs ppm ppm dB mA V V
VOERR
TCVO −40°C < TA < +125°C −40°C < TA < +125°C VIN = 5 V to 18 V, −40°C < TA < +125°C IL = 0 mA to 10 mA, VIN = 6 V, −40°C < TA < +125°C IL = −10 mA to 0 mA, VIN = 6 V, −40°C < TA < +125°C No load, −40°C < TA < +125°C 0.1 Hz to 10.0 Hz 1 kHz CL = 0 μF 1000 hours fIN = 1 kHz 2 1 5 10 3 20 15 15 800
∆VO/∆VIN ∆VO/∆IL ∆VO/∆IL IIN eN p-p eN tR ∆VO VO_HYS RRR ISC VIN VIN − VO
590 3.75 90 10 40 20 −70 40 5.0 2
18
Initial accuracy does not include shift due to solder heat effect. The long-term stability specification is noncumulative. The drift in subsequent 1000 hour periods is significantly lower than in the first 1000 hour period.
Rev. J | Page 6 of 24
ADR430/ADR431/ADR433/ADR434/ADR435/ADR439
ADR434 ELECTRICAL CHARACTERISTICS
VIN = 6.1 V to 18 V, IL = 0 mA, TA = 25°C, unless otherwise noted. Table 5.
Parameter OUTPUT VOLTAGE A Grade B Grade INITIAL ACCURACY 1 A Grade B Grade TEMPERATURE COEFFICIENT A Grade B Grade LINE REGULATION LOAD REGULATION QUIESCENT CURRENT VOLTAGE NOISE VOLTAGE NOISE DENSITY TURN-ON SETTLING TIME LONG-TERM STABILITY 2 OUTPUT VOLTAGE HYSTERESIS RIPPLE REJECTION RATIO SHORT CIRCUIT TO GND SUPPLY VOLTAGE OPERATING RANGE SUPPLY VOLTAGE HEADROOM
1 2
Symbol VO
Conditions
Min 4.091 4.0945
Typ 4.096 4.096
Max 4.101 4.0975 ±5 ±0.12 ±1.5 ±0.04
Unit V V mV % mV % ppm/°C ppm/°C ppm/V ppm/mA ppm/mA μA μV p-p nV/√Hz μs ppm ppm dB mA V V
VOERR
TCVO −40°C < TA < +125°C −40°C < TA < +125°C VIN = 6.1 V to 18 V, −40°C < TA < +125°C IL = 0 mA to 10 mA, VIN = 7 V, −40°C < TA < +125°C IL = −10 mA to 0 mA, VIN = 7 V, −40°C < TA < +125°C No load, −40°C < TA < +125°C 0.1 Hz to 10.0 Hz 1 kHz CL = 0 μF 1000 hours fIN = 1 kHz 2 1 5 10 3 20 15 15 800
∆VO/∆VIN ∆VO/∆IL ∆VO/∆IL IIN eN p-p eN tR ∆VO VO_HYS RRR ISC VIN VIN − VO
595 6.25 100 10 40 20 −70 40 6.1 2
18
Initial accuracy does not include shift due to solder heat effect. The long-term stability specification is noncumulative. The drift in subsequent 1000 hour periods is significantly lower than in the first 1000 hour period.
Rev. J | Page 7 of 24
ADR430/ADR431/ADR433/ADR434/ADR435/ADR439
ADR435 ELECTRICAL CHARACTERISTICS
VIN = 7.0 V to 18 V, IL = 0 mA, TA = 25°C, unless otherwise noted. Table 6.
Parameter OUTPUT VOLTAGE A Grade B Grade INITIAL ACCURACY 1 A Grade B Grade TEMPERATURE COEFFICIENT A Grade B Grade LINE REGULATION LOAD REGULATION QUIESCENT CURRENT VOLTAGE NOISE VOLTAGE NOISE DENSITY TURN-ON SETTLING TIME LONG-TERM STABILITY 2 OUTPUT VOLTAGE HYSTERESIS RIPPLE REJECTION RATIO SHORT CIRCUIT TO GND SUPPLY VOLTAGE OPERATING RANGE SUPPLY VOLTAGE HEADROOM
1 2
Symbol VO
Conditions
Min 4.994 4.998
Typ 5.000 5.000
Max 5.006 5.002 ±6 ±0.12 ±2 ±0.04
Unit V V mV % mV % ppm/°C ppm/°C ppm/V ppm/mA ppm/mA μA μV p-p nV/√Hz μs ppm ppm dB mA V V
VOERR
TCVO −40°C < TA < +125°C −40°C < TA < +125°C VIN = 7 V to 18 V, −40°C < TA < +125°C IL = 0 mA to 10 mA, VIN = 8 V, −40°C < TA < +125°C IL = −10 mA to 0 mA, VIN = 8 V, −40°C < TA < +125°C No load, −40°C < TA < +125°C 0.1 Hz to 10 Hz 1 kHz CL = 0 μF 1000 hours fIN = 1 kHz 7.0 2 2 1 5 10 3 20 15 15 800
∆VO/∆VIN ∆VO/∆IL ∆VO/∆IL IIN eN p-p eN tR ∆VO VO_HYS RRR ISC VIN VIN − VO
620 8 115 10 40 20 −70 40
18
Initial accuracy does not include shift due to solder heat effect. The long-term stability specification is noncumulative. The drift in subsequent 1000 hour periods is significantly lower than in the first 1000 hour period.
Rev. J | Page 8 of 24
ADR430/ADR431/ADR433/ADR434/ADR435/ADR439
ADR439 ELECTRICAL CHARACTERISTICS
VIN = 6.5 V to 18 V, IL = 0 mV, TA = 25°C, unless otherwise noted. Table 7.
Parameter OUTPUT VOLTAGE A Grade B Grade INITIAL ACCURACY 1 A Grade B Grade TEMPERATURE COEFFICIENT A Grade B Grade LINE REGULATION LOAD REGULATION QUIESCENT CURRENT VOLTAGE NOISE VOLTAGE NOISE DENSITY TURN-ON SETTLING TIME LONG-TERM STABILITY 2 OUTPUT VOLTAGE HYSTERESIS RIPPLE REJECTION RATIO SHORT CIRCUIT TO GND SUPPLY VOLTAGE OPERATING RANGE SUPPLY VOLTAGE HEADROOM
1 2
Symbol VO
Conditions
Min 4.4946 4.498
Typ 4.500 4.500
Max 4.5054 4.502 ±5.5 ±0.12 ±2 ±0.04
Unit V V mV % mV % ppm/°C ppm/°C ppm/V ppm/mA ppm/mA μA μV p-p nV/√Hz μs ppm ppm dB mA V V
VOERR
TCVO −40°C < TA < +125°C −40°C < TA < +125°C VIN = 6.5 V to 18 V, −40°C < TA < +125°C IL = 0 mA to 10 mA, VIN = 6.5 V, −40°C < TA < +125°C IL = −10 mA to 0 mA, VIN = 6.5 V, −40°C < TA < +125°C No load, −40°C < TA < +125°C 0.1 Hz to 10.0 Hz 1 kHz CL = 0 μF 1000 hours fIN = 1 kHz 6.5 2 2 1 5 10 3 20 15 15 800
∆VO/∆VIN ∆VO/∆IL ∆VO/∆IL IIN eN p-p eN tR ∆VO VO_HYS RRR ISC VIN VIN − VO
600 7.5 110 10 40 20 −70 40
18
Initial accuracy does not include shift due to solder heat effect. The long-term stability specification is noncumulative. The drift in subsequent 1000 hour periods is significantly lower than in the first 1000 hour period.
Rev. J | Page 9 of 24
ADR430/ADR431/ADR433/ADR434/ADR435/ADR439 ABSOLUTE MAXIMUM RATINGS
TA = 25°C, unless otherwise noted. Table 8.
Parameter Supply Voltage Output Short-Circuit Duration to GND Storage Temperature Range Operating Temperature Range Junction Temperature Range Lead Temperature, Soldering (60 sec) Rating 20 V Indefinite −65°C to +150°C −40°C to +125°C −65°C to +150°C 300°C
THERMAL RESISTANCE
θJA is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages. Table 9. Thermal Resistance
Package Type 8-Lead SOIC_N (R) 8-Lead MSOP (RM) θJA 130 142 θJC 43 44 Unit °C/W °C/W
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.
ESD CAUTION
Rev. J | Page 10 of 24
ADR430/ADR431/ADR433/ADR434/ADR435/ADR439 TYPICAL PERFORMANCE CHARACTERISTICS
Default conditions: ±5 V, CL = 5 pF, G = 2, RG = RF = 1 kΩ, RL = 2 kΩ, VO = 2 V p-p, f = 1 MHz, TA = 25°C, unless otherwise noted.
0.8
2.5009 2.5007 2.5005 2.5003 2.5001 2.4999 2.4997 2.4995 –40
0.7
+125°C
SUPPLY CURRENT (mA)
OUTPUT VOLTAGE (V)
0.6
+25°C –40°C
0.5
0.4
04500-015
TEMPERATURE (°C)
INPUT VOLTAGE (V)
Figure 3. ADR431 Output Voltage vs. Temperature
Figure 6. ADR435 Supply Current vs. Input Voltage
4.0980
700
4.0975
650
SUPPLY CURRENT (µA)
OUTPUT VOLTAGE (V)
4.0970
600
4.0965
550
4.0960
500
4.0955
450
04500-016
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 4. ADR434 Output Voltage vs. Temperature
Figure 7. ADR435 Supply Current vs. Temperature
5.0025 5.0020 5.0015 5.0010 5.0005 5.0000 4.9995 4.9990 –40 SUPPLY CURRENT (mA)
0.60 0.58 0.56 +125°C
OUTPUT VOLTAGE (V)
0.54 0.52 0.50 0.48 0.46 0.44 0.42 0.40 –40°C +25°C
04500-017
TEMPERATURE (°C)
INPUT VOLTAGE (V)
Figure 5. ADR435 Output Voltage vs. Temperature
Figure 8. ADR431 Supply Current vs. Input Voltage
Rev. J | Page 11 of 24
04500-020
–25
–10
5
20
35
50
65
80
95
110
125
6
8
10
12
14
16
18
04500-019
4.0950 –40
–25
–10
5
20
35
50
65
80
95
110
125
400 –40
–25
–10
5
20
35
50
65
80
95
110
125
04500-018
–25
–10
5
20
35
50
65
80
95
110
125
0.3
4
6
8
10
12
14
16
ADR430/ADR431/ADR433/ADR434/ADR435/ADR439
610 580
2.5
SUPPLY CURRENT (µA)
550 520 490 460 430 400 –40
DIFFERENTIAL VOLTAGE (V)
2.0 –40°C 1.5 +25°C 1.0
+125°C
0.5
04500-021
TEMPERATURE (°C)
LOAD CURRENT (mA)
Figure 9. ADR431 Supply Current vs. Temperature
15
1.9
Figure 12. ADR431 Minimum Input/Output Differential Voltage vs. Load Current
NO LOAD 1.8
IL = 0mA to 10mA
LOAD REGULATION (ppm/mA)
12
MINIMUM HEADROOM (V)
1.7 1.6 1.5 1.4 1.3 1.2 1.1
9
6
3
04500-022
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 10. ADR431 Load Regulation vs. Temperature
15
Figure 13. ADR431 Minimum Headroom vs. Temperature
2.5
IL = 0mA to 10mA
LOAD REGULATION (ppm/mA)
DIFFERENTIAL VOLTAGE (V)
12
2.0 –40°C 1.5 +25°C 1.0 +125°C 0.5
9
6
3
04500-023
TEMPERATURE (°C)
LOAD CURRENT (mA)
Figure 11. ADR435 Load Regulation vs. Temperature
Figure 14. ADR435 Minimum Input/Output Differential Voltage vs. Load Current
Rev. J | Page 12 of 24
04500-026
0 –40
–25
–10
5
20
35
50
65
80
95
110
125
0 –10
–5
0
5
10
04500-025
0 –40
–25
–10
5
20
35
50
65
80
95
110
125
1.0 –40
–25
–10
5
20
35
50
65
80
95
110
125
04500-024
–25
–10
5
20
35
50
65
80
95
110
125
0 –10
–5
0
5
10
ADR430/ADR431/ADR433/ADR434/ADR435/ADR439
1.9 NO LOAD 1.7
MINIMUM HEADROOM (V)
CL = 0.01µF NO INPUT CAPACITOR VO = 1V/DIV
1.5
1.3
1.1
VIN = 2V/DIV
04500-027
TEMPERATURE (°C)
Figure 15. ADR435 Minimum Headroom vs. Temperature
Figure 18. ADR431 Turn-On Response, 0.01 μF Load Capacitor
20 VIN = 7V TO 18V 16 LINE REGULATION (ppm/V)
VO = 1V/DIV CIN = 0.01µF NO LOAD
12
8
4
0
VIN = 2V/DIV
TIME = 4µs/DIV
TEMPERATURE (°C)
04500-028
Figure 16. ADR435 Line Regulation vs. Temperature
Figure 19. ADR431 Turn-Off Response
CIN = 0.01µF NO LOAD VO = 1V/DIV
BYPASS CAPACITOR = 0µF
LINE INTERRUPTION
VIN = 500mV/DIV
VO = 50mV/DIV
VIN = 2V/DIV
04500-030
Figure 17. ADR431 Turn-On Response
Figure 20. ADR431 Line Transient Response
Rev. J | Page 13 of 24
04500-033
TIME = 4µs/DIV
TIME = 100µs/DIV
04500-032
–4 –40
–25
–10
5
20
35
50
65
80
95
110
125
04500-031
0.9 –40
–25
–10
5
20
35
50
65
80
95
110
125
TIME = 4µs/DIV
ADR430/ADR431/ADR433/ADR434/ADR435/ADR439
BYPASS CAPACITOR = 0.1µF LINE INTERRUPTION VIN = 500mV/DIV
VO = 50mV/DIV
2µV/DIV
04500-034
TIME = 1s/DIV
Figure 21. ADR431 Line Transient Response, 0.1 μF Bypass Capacitor
Figure 24. ADR435 0.1 Hz to 10.0 Hz Voltage Noise
1µV/DIV
50µV/DIV
04500-035
Figure 22. ADR431 0.1 Hz to 10.0 Hz Voltage Noise
Figure 25. ADR435 10 Hz to 10 kHz Voltage Noise
14 12 10 8 6 4 2 0 –110 –90
50µV/DIV
04500-036
DEVIATION (PPM)
Figure 23. ADR431 10 Hz to 10 kHz Voltage Noise
Figure 26. ADR431 Typical Hysteresis
Rev. J | Page 14 of 24
04500-029
TIME = 1s/DIV
NUMBER OF PARTS
–70
–50
–30
–10
10
30
50
70
90
04500-038
TIME = 1s/DIV
TIME = 1s/DIV
04500-037
TIME = 100µs/DIV
110
ADR430/ADR431/ADR433/ADR434/ADR435/ADR439
50 45 40 OUTPUT IMPEDANCE (Ω) 35 30 25 20 15 10 5 0 100 1k 10k FREQUENCY (Hz) ADR430 ADR435
10 –10 –30 –50 –70 –90 –110 –130 –150 FREQUENCY (Hz)
04500-040
04500-039
ADR433
100k
RIPPLE REJECTION (dB)
10
100
1k
10k
100k
1M
Figure 27. Output Impedance vs. Frequency
Figure 28. Ripple Rejection
Rev. J | Page 15 of 24
ADR430/ADR431/ADR433/ADR434/ADR435/ADR439 THEORY OF OPERATION
The ADR43x series of references uses a reference generation technique known as XFET (eXtra implanted junction FET). This technique yields a reference with low supply current, good thermal hysteresis, and exceptionally low noise. The core of the XFET reference consists of two junction field-effect transistors (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 can be compensated closely by adding a correction term generated in the same fashion as the proportional-to-temperature (PTAT) term used to compensate band gap references. The primary advantage of an XFET reference is its correction term, which is ~30 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 29 shows the basic topology of the ADR43x series. The temperature correction term is provided by a current source with a value designed to be proportional to absolute temperature. The general equation is VOUT = G (ΔVP – R1 × IPTAT) (1) where: G is the gain of the reciprocal of the divider ratio. ΔVP is the difference in pinch-off voltage between the two JFETs. IPTAT is the positive temperature coefficient correction current. ADR43x devices are created by on-chip adjustment of R2 and R3 to achieve 2.048 V or 2.500 V, respectively, at the reference output.
I1 IPTAT I1 VIN
The ADR43x family of references is guaranteed to deliver load currents to 10 mA with an input voltage that ranges from 4.1 V to 18 V. When these devices are used in applications at higher currents, use the following equation to account for the temperature effects due to the power dissipation increases: 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
Voltage references, in general, require a bypass capacitor connected from VOUT to GND. The circuit in Figure 30 illustrates the basic configuration for the ADR43x family of references. Other than a 0.1 μF capacitor at the output to help improve noise suppression, a large output capacitor at the output is not required for circuit stability.
TP VIN 10µF
+
1 2 8
TP
0.1µF
NC GND
COMP VOUT TOP VIEW 6 (Not to Scale) 4 5 TRIM
7 3
ADR43x
0.1µF
Figure 30. Basic Voltage Reference Configuration
NOISE PERFORMANCE
The noise generated by the ADR43x family of references is typically less than 3.75 μV p-p over the 0.1 Hz to 10.0 Hz band for ADR430, ADR431, and ADR433. Figure 22 shows the 0.1 Hz to 10.0 Hz noise of the ADR431, which is only 3.5 μV p-p. The noise measurement is made with a band-pass filter made of a 2-pole high-pass filter with a corner frequency at 0.1 Hz and a 2-pole low-pass filter with a corner frequency at 10.0 Hz.
ADR43x
VOUT R2
HIGH FREQUENCY NOISE
The total noise generated by the ADR43x family of references is composed of the reference noise and the op amp noise. Figure 31 shows the wideband noise from 10 Hz to 25 kHz. An internal node of the op amp is brought out on Pin 7, and by overcompensating the op amp, the overall noise can be reduced. This is understood by considering that in a closed-loop configuration, the effective output impedance of an op amp is
* ∆VP
R1
R3
*EXTRA CHANNEL IMPLANT VOUT = G(∆VP – R1 × IPTAT)
GND
Figure 29. Simplified Schematic Device Power Dissipation Considerations
04500-002
RO =
rO 1 + AVO β
04500-044
NOTES: 1. NC = NO CONNECT 2. TP = TEST PIN (DO NOT CONNECT)
(3)
where: RO is the apparent output impedance. rO is the output resistance of the op amp. AVO is the open-loop gain at the frequency of interest. β is the feedback factor.
Rev. J | Page 16 of 24
ADR430/ADR431/ADR433/ADR434/ADR435/ADR439
Equation 3 shows that the apparent output impedance is reduced by approximately the excess loop gain; therefore, as the frequency increases, the excess loop gain decreases, and the apparent output impedance increases. A passive element whose impedance increases as its frequency increases is an inductor. When a capacitor is added to the output of an op amp or a reference, it forms a tuned circuit that resonates at a certain frequency and results in gain peaking. This can be observed by using a model of a semiperfect op amp with a single-pole response and some pure resistance in series with the output. Changing capacitive loads results in peaking at different frequencies. For most normal op amp applications with low capacitive loading (
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