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| Ultralow Noise, LDO XFET(R) Voltage References with Current Sink and Source ADR440/ADR441/ADR443/ADR444/ADR445 FEATURES Ultralow noise (0.1 Hz to 10 Hz) ADR440: 1 V p-p ADR441: 1.2 V p-p ADR443: 1.4 V p-p ADR444: 1.8 V p-p ADR445: 2.25 V 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 Wide temperature range: -40C to +125C PIN CONFIGURATIONS TP 1 VIN 2 NC 3 ADR440/ ADR441/ ADR443/ ADR444/ ADR445 TOP VIEW (Not to Scale) 8 7 6 5 TP NC VOUT TRIM 05428-001 05428-002 GND 4 NOTES 1. NC = NO CONNECT 2. TP = TEST PIN (DO NOT CONNECT) Figure 1. 8-Lead SOIC_N (R-Suffix) TP 1 VIN 2 NC 3 GND 4 ADR440/ ADR441/ ADR443/ ADR444/ ADR445 TOP VIEW (Not to Scale) 8 7 6 5 TP NC VOUT TRIM APPLICATIONS Precision data acquisition systems High resolution data converters Battery-powered instrumentations Portable medical instruments Industrial process control systems Precision instruments Optical control circuits NOTES 1. NC = NO CONNECT 2. TP = TEST PIN (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 available in 8-lead MSOP and narrow SOIC packages. All versions are specified over the extended industrial temperature range of -40C to +125C. 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 Initial Accuracy, (mV) 3 1 3 1 4 1.2 5 1.6 6 2 Temperature Coefficient (ppm/C) 10 3 10 3 10 3 10 3 10 3 Model ADR440A ADR440B ADR441A ADR441B ADR443A ADR443B ADR444A ADR444B ADR445A ADR445B Rev. A 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 (c)2006 Analog Devices, Inc. All rights reserved. ADR440/ADR441/ADR443/ADR444/ADR445 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..................................................................................... 15 Output Adjustment .................................................................... 15 Bipolar Outputs .......................................................................... 15 Negative Reference..................................................................... 15 Programmable Voltage Source ................................................. 16 Programmable Current Source ................................................ 16 High Voltage Floating Current Source .................................... 16 Precision Output Regulator (Boosted Reference).................. 17 Outline Dimensions ....................................................................... 18 Ordering Guide .......................................................................... 19 REVISION HISTORY 9/06--Rev. 0 to Rev. A Updated Format..................................................................Universal Changes to Features.......................................................................... 1 Changes to Pin Configurations....................................................... 1 Changes to the 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 the 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 Rev. A | Page 2 of 20 ADR440/ADR441/ADR443/ADR444/ADR445 SPECIFICATIONS ADR440 ELECTRICAL CHARACTERISTICS VIN = 3 V to 18 V, TA = 25C, CIN = COUT = 0.1 F, unless otherwise noted. Table 2. Parameter OUTPUT VOLTAGE A Grade B Grade INITIAL ACCURACY A Grade B Grade TEMPERATURE DRIFT A Grade B Grade LINE REGULATION LOAD REGULATION TCVO -40C < TA < +125C -40C < TA < +125C -40C < TA < +125C ILOAD = 0 mA to 10 mA, VIN = 3.5 V, -40C < TA < +125C ILOAD = 0 mA to -5 mA, VIN = 3.5 V, -40C < TA < +125C No load, -40C < TA < +125C 0.1 Hz to 10 Hz 1 kHz 1000 hours fIN = 10 kHz 3 500 2 1 +10 10 3 +20 +50 +50 3.75 ppm/C ppm/C ppm/V ppm/mA ppm/mA mA V p-p nV/Hz s ppm ppm dB mA V mV Symbol VO Conditions Min 2.045 2.047 VOERR 3 0.15 1 0.05 mV % mV % Typ 2.048 2.048 Max 2.051 2.049 Unit V V VO/VIN VO/ILOAD VO/ILOAD -20 -50 -50 QUIESCENT CURRENT VOLTAGE NOISE VOLTAGE NOISE DENSITY TURN-ON SETTLING TIME LONG-TERM STABILITY 1 OUTPUT VOLTAGE HYSTERESIS RIPPLE REJECTION RATIO SHORT CIRCUIT TO GND SUPPLY VOLTAGE OPERATING RANGE SUPPLY VOLTAGE HEADROOM 1 IIN eN p-p eN tR VO VO_HYS RRR ISC VIN VIN - VO 3 1 45 10 50 70 -75 27 18 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. Rev. A | Page 3 of 20 ADR440/ADR441/ADR443/ADR444/ADR445 ADR441 ELECTRICAL CHARACTERISTICS VIN = 3 V to 18 V, TA = 25C, CIN = COUT = 0.1 F, unless otherwise noted. Table 3. Parameter OUTPUT VOLTAGE A Grade B Grade INITIAL ACCURACY A Grade B Grade TEMPERATURE DRIFT A Grade B Grade LINE REGULATION LOAD REGULATION TCVO -40C < TA < +125C -40C < TA < +125C -40C < TA < +125C ILOAD = 0 mA to 10 mA, VIN = 4 V, -40C < TA < +125C ILOAD = 0 mA to -5 mA, VIN = 4 V, -40C < TA < +125C No load, -40C < TA < +125C 0.1 Hz to 10 Hz 1 kHz 1000 hours fIN = 10 kHz 3 500 2 1 10 -50 -50 3 1.2 48 10 50 70 -75 27 10 3 20 +50 +50 3.75 ppm/C ppm/C ppm/V ppm/mA ppm/mA mA V p-p nV/Hz s ppm ppm dB mA V mV Symbol VO Conditions Min 2.497 2.499 VOERR 3 0.12 1 0.04 mV % mV % Typ 2.500 2.500 Max 2.503 2.501 Unit V V VO/VIN VO/ILOAD VO/ILOAD QUIESCENT CURRENT VOLTAGE NOISE VOLTAGE NOISE DENSITY TURN-ON SETTLING TIME LONG-TERM STABILITY 1 OUTPUT VOLTAGE HYSTERESIS RIPPLE REJECTION RATIO SHORT CIRCUIT TO GND SUPPLY VOLTAGE OPERATING RANGE SUPPLY VOLTAGE HEADROOM 1 IIN eN p-p eN tR VO VO_HYS RRR ISC VIN VIN - VO 18 The long-term stability specification is noncumulative. The drift in subsequent 1000-hour period is significantly lower than in the first 1000-hour period. Rev. A | Page 4 of 20 ADR440/ADR441/ADR443/ADR444/ADR445 ADR443 ELECTRICAL CHARACTERISTICS VIN = 3.5 V to 18 V, TA = 25C, CIN = COUT = 0.1 F, unless otherwise noted. Table 4. Parameter OUTPUT VOLTAGE A Grade B Grade INITIAL ACCURACY A Grade B Grade TEMPERATURE DRIFT A Grade B Grade LINE REGULATION LOAD REGULATION TCVO -40C < TA < +125C -40C < TA < +125C -40C < TA < +125C ILOAD = 0 mA to 10 mA, VIN = 5 V, -40C < TA < +125C ILOAD = 0 mA to -5 mA, VIN = 5 V, -40C < TA < +125C No load, -40C < TA < +125C 0.1 Hz to 10 Hz 1 kHz 1000 hours fIN = 10 kHz 3.5 500 2 1 10 -50 -50 3 1.4 57.6 10 50 70 -75 27 10 3 20 +50 +50 3.75 ppm/C ppm/C ppm/V ppm/mA ppm/mA mA V p-p nV/Hz s ppm ppm dB mA V mV Symbol VO Conditions Min 2.996 2.9988 VOERR 4 0.13 1.2 0.04 mV % mV % Typ 3.000 3.000 Max 3.004 3.0012 Unit V V VO/VIN VO/ILOAD VO/ILOAD QUIESCENT CURRENT VOLTAGE NOISE VOLTAGE NOISE DENSITY TURN-ON SETTLING TIME LONG-TERM STABILITY 1 OUTPUT VOLTAGE HYSTERESIS RIPPLE REJECTION RATIO SHORT CIRCUIT TO GND SUPPLY VOLTAGE OPERATING RANGE SUPPLY VOLTAGE HEADROOM 1 IIN eN p-p eN tR VO VO_HYS RRR ISC VIN VIN - VO 18 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. Rev. A | Page 5 of 20 ADR440/ADR441/ADR443/ADR444/ADR445 ADR444 ELECTRICAL CHARACTERISTICS VIN = 4.6 V to 18 V, TA = 25C, CIN = COUT = 0.1 F, unless otherwise noted. Table 5. Parameter OUTPUT VOLTAGE A Grade B Grade INITIAL ACCURACY A Grade B Grade TEMPERATURE DRIFT A Grade B Grade LINE REGULATION LOAD REGULATION TCVO -40C < TA < +125C -40C < TA < +125C -40C < TA < +125C ILOAD = 0 mA to 10 mA, VIN = 5.5 V, -40C < TA < +125C ILOAD = 0 mA to -5 mA, VIN = 5.5 V, -40C < TA < +125C No load, -40C < TA < +125C 0.1 Hz to 10 Hz 1 kHz 1000 hours fIN = 10 kHz 4.6 500 2 1 10 -50 -50 3 1.8 78.6 10 50 70 -75 27 10 3 20 +50 +50 3.75 ppm/C ppm/C ppm/V ppm/mA ppm/mA mA V p-p nV/Hz s ppm ppm dB mA V mV Symbol VO Conditions Min 4.091 4.0944 VOERR 5 0.13 1.6 0.04 mV % mV % Typ 4.096 4.096 Max 4.101 4.0976 Unit V V VO/VIN VO/ILOAD VO/ILOAD QUIESCENT CURRENT VOLTAGE NOISE VOLTAGE NOISE DENSITY TURN-ON SETTLING TIME LONG-TERM STABILITY 1 OUTPUT VOLTAGE HYSTERESIS RIPPLE REJECTION RATIO SHORT CIRCUIT TO GND SUPPLY VOLTAGE OPERATING RANGE SUPPLY VOLTAGE HEADROOM 1 IIN eN p-p eN tR VO VO_HYS RRR ISC VIN VIN - VO 18 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. Rev. A | Page 6 of 20 ADR440/ADR441/ADR443/ADR444/ADR445 ADR445 ELECTRICAL CHARACTERISTICS VIN = 5.5 V to 18 V, TA = 25C, CIN = COUT = 0.1 F, unless otherwise noted. Table 6. Parameter OUTPUT VOLTAGE A Grade B Grade INITIAL ACCURACY A Grade B Grade TEMPERATURE DRIFT A Grade B Grade LINE REGULATION LOAD REGULATION TCVO -40C < TA < +125C -40C < TA < +125C -40C < TA < +125C ILOAD = 0 mA to 10 mA, VIN = 6.5 V, -40C < TA < +125C ILOAD = 0 mA to -5 mA, VIN = 6.5 V, -40C < TA < +125C No load, -40C < TA < +125C 0.1 Hz to 10 Hz 1 kHz 1000 hours fIN = 10 kHz 5.5 500 2 1 10 -50 -50 3 2.25 90 10 50 70 -75 27 10 3 20 +50 +50 3.75 ppm/C ppm/C ppm/V ppm/mA ppm/mA mA V p-p nV/Hz s ppm ppm dB mA V mV Symbol VO Conditions Min 4.994 4.998 VOERR 6 0.12 2 0.04 mV % mV % Typ 5.000 5.000 Max 5.006 5.002 Unit V V VO/VIN VO/ILOAD VO/ILOAD QUIESCENT CURRENT VOLTAGE NOISE VOLTAGE NOISE DENSITY TURN-ON SETTLING TIME LONG-TERM STABILITY 1 OUTPUT VOLTAGE HYSTERESIS RIPPLE REJECTION RATIO SHORT CIRCUIT TO GND SUPPLY VOLTAGE OPERATING RANGE SUPPLY VOLTAGE HEADROOM 1 IIN eN p-p eN tR VO VO_HYS RRR ISC VIN VIN - VO 18 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. Rev. A | Page 7 of 20 ADR440/ADR441/ADR443/ADR444/ADR445 ABSOLUTE MAXIMUM RATINGS TA = 25C, unless otherwise noted. Table 7. 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 -65C to +125C -40C to +125C -65C to +150C 300C THERMAL RESISTANCE JA 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 8-Lead SOIC_N (R-Suffix) 8-Lead MSOP (RM-Suffix) JA 130 190 JC 43 Unit C/W C/W ESD CAUTION 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. Rev. A | Page 8 of 20 ADR440/ADR441/ADR443/ADR444/ADR445 TYPICAL PERFORMANCE CHARACTERISTICS VIN = 7 V, TA = 25C, CIN = COUT = 0.1 F, unless otherwise noted. 2.5020 2.051 2.5015 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 2.050 2.5010 2.049 2.5005 2.048 2.5000 2.047 05428-003 2.4990 -40 -25 -10 5 20 35 50 65 TEMPERATURE (C) 80 95 110 125 2.045 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C) Figure 3. ADR441 Output Voltage vs. Temperature 3.0020 3.0015 OUTPUT VOLTAGE (V) Figure 6. ADR440 Output Voltage vs. Temperature 5.006 5.004 UNIT 1 UNIT 2 3.0010 OUTPUT VOLTAGE (V) 5.002 3.0005 3.0000 2.9995 2.9990 5.000 UNIT 3 4.998 4.996 05428-004 2.9985 2.9980 -40 -25 -10 5 20 35 50 65 TEMPERATURE (C) 80 95 110 125 4.994 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C) Figure 4. ADR443 Output Voltage vs. Temperature 4.0980 4.0975 4.0970 Figure 7. ADR445 Output Voltage vs. Temperature 4.0 UNIT 1 4.0965 4.0960 UNIT 3 4.0955 4.0950 05428-005 SUPPLY CURRENT (mA) 3.5 +125C OUTPUT VOLTAGE (V) UNIT 2 3.0 +25C -40C 2.5 05428-006 4.0945 4.0940 -40 -25 -10 5 20 35 50 65 TEMPERATURE (C) 80 95 110 125 2.0 4 6 8 10 12 INPUT VOLTAGE (V) 14 16 18 Figure 5. ADR444 Output Voltage vs. Temperature Figure 8. ADR441 Supply Current vs. Input Voltage Rev. A | Page 9 of 20 05428-043 05428-042 2.4995 2.046 ADR440/ADR441/ADR443/ADR444/ADR445 4.0 10 LINE REGULATION (ppm/V) SUPPLY CURRENT (mA) 3.5 8 6 3.0 4 2.5 05428-007 2 05428-010 2.0 -40 -25 -10 5 20 35 50 65 TEMPERATURE (C) 80 95 110 125 0 -40 -25 -10 5 20 35 50 65 TEMPERATURE (C) 80 95 110 125 Figure 9. ADR441 Supply Current vs. Temperature 3.5 3.4 LOAD REGULATION (ppm/mA) Figure 12. ADR441 Line Regulation vs. Temperature 60 3.3 SUPPLY CURRENT (mA) 55 VIN = 18V 50 3.2 3.1 3.0 2.9 2.8 2.7 2.6 2.5 5.3 7.3 9.3 11.3 13.3 15.3 INPUT VOLTAGE (V) 17.3 -40C 05428-008 +125C 45 VIN = 6V 40 ILOAD = 0mA TO 10mA +25C 35 05428-011 19.3 30 -40 -25 -10 5 20 35 50 65 TEMPERATURE (C) 80 95 110 125 Figure 10. ADR445 Supply Current vs. Input Voltage 3.25 Figure 13. ADR441 Load Regulation vs. Temperature 7 6 QUIESCENT CURRENT (mA) LINE REGULATIOIN (ppm/V) 3.15 5 4 3 2 1 0 -40 3.05 2.95 2.85 05428-009 05428-012 2.75 -40 -25 -10 5 20 35 50 65 TEMPERATURE (C) 80 95 110 125 -25 -10 5 20 35 50 65 TEMPERATURE (C) 80 95 110 125 Figure 11. ADR445 Quiescent Current vs. Temperature Figure 14. ADR445 Line Regulation vs. Temperature Rev. A | Page 10 of 20 ADR440/ADR441/ADR443/ADR444/ADR445 50 40 LOAD REGULATION (ppm/mA) DIFFERENTIAL VOLTAGE (V) 1.0 0.9 ILOAD = 0mA TO +10mA 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 -5 0 5 LOAD CURRENT (mA) 05428-016 30 20 10 0 -10 -20 -30 -40 -50 -40 +125C VIN = 6V +25C -40C ILOAD = 0mA TO -5mA 05428-013 -25 -10 5 20 35 50 65 TEMPERATURE (C) 80 95 110 125 10 Figure 15. ADR445 Load Regulation vs. Temperature Figure 18. ADR445 Minimum Input/Output Differential Voltage vs. Load Current 0.5 NO LOAD 0.7 0.6 DIFFERENTIAL VOLTAGE (V) 0.4 0.5 0.4 0.3 0.2 0.1 0 -10 +125C +25C -40C MINIMUM HEADROOM (V) 05428-014 0.3 0.2 0.1 05428-017 -5 0 LOAD CURRENT (mA) 5 10 0 -40 -25 -10 5 20 35 50 65 TEMPERATURE (C) 80 95 110 125 Figure 16. ADR441 Minimum Input/Output Differential Voltage vs. Load Current 0.5 NO LOAD 0.4 MINIMUM HEADROOM (V) Figure 19. ADR445 Minimum Headroom vs. Temperature CIN, COUT = 0.1F 0.3 VIN = 5V/DIV 0.2 0.1 05428-015 VOUT = 1V/DIV TIME = 10s/DIV 05428-018 0 -40 -25 -10 5 20 35 50 65 TEMPERATURE (C) 80 95 110 125 Figure 17. ADR441 Minimum Headroom vs. Temperature Figure 20. ADR441 Turn-On Response Rev. A | Page 11 of 20 ADR440/ADR441/ADR443/ADR444/ADR445 CIN, COUT = 0.1F CIN, COUT = 0.1F LOAD OFF VIN = 5V/DIV LOAD ON 5mV/DIV VOUT = 1V/DIV 05428-019 TIME = 200s/DIV TIME = 200s/DIV Figure 21. ADR441 Turn-Off Response Figure 24. ADR441 Load Transient Response CIN = 0.1F COUT = 10F CIN = 0.1F COUT = 10F LOAD OFF LOAD ON VIN = 5V/DIV 5mV/DIV VOUT = 1V/DIV 05428-020 05428-023 TIME = 200s/DIV TIME = 200s/DIV Figure 22. ADR441 Turn-On Response Figure 25. ADR441 Load Transient Response CIN = 0.1F COUT = 10F 2V/DIV 4V 1V/DIV CH1 p-p 1.18V 2mV/DIV 05428-021 TIME = 100s/DIV TIME = 1s/DIV Figure 23. ADR441 Line Transient Response Figure 26. ADR441 0.1 Hz to 10.0 Hz Voltage Noise Rev. A | Page 12 of 20 05428-024 05428-022 ADR440/ADR441/ADR443/ADR444/ADR445 16 14 12 NUMBER OF PARTS 10 8 6 4 05428-028 50V/DIV CH1 p-p 49V 2 0 90 -30 -10 110 -110 -90 -70 -50 -150 TIME = 1s/DIV 05428-025 -130 DEVIATION (PPM) Figure 27. ADR441 10 Hz to 10 kHz Voltage Noise 10 9 8 Figure 30. ADR441 Typical Output Voltage Hysteresis OUTPUT IMPEDANCE () 7 6 5 4 3 2 1 ADR445 1V/DIV CH1 p-p 2.24V ADR443 130 05428-026 TIME = 1s/DIV 0 10 100 1k FREQUENCY (Hz) 10k 100k Figure 28. ADR445 0.1 Hz to 10.0 Hz Voltage Noise 0 -10 RIPPLE REJECTION RATIO (dB) Figure 31. Output Impedance vs. Frequency -20 -30 -40 -50 -60 -70 -80 -90 05428-030 50V/DIV CH1 p-p 66V 05428-027 TIME = 1s/DIV -100 100 1k 10k FREQUENCY (Hz) 100k 1M Figure 29. ADR445 10 Hz to 10 kHz Voltage Noise Figure 32. Ripple Rejection Ratio vs. Frequency Rev. A | Page 13 of 20 05428-029 ADR441 150 10 30 50 70 ADR440/ADR441/ADR443/ADR444/ADR445 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-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 absolute temperature. The general equation is 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, users should use the following equation to account for the temperature effects of increases in power dissipation: TJ = PD x JA + TA where: TJ and TA are the junction and ambient temperatures, respectively. PD is the device power dissipation. JA is the device package thermal resistance. (2) BASIC VOLTAGE REFERENCE CONNECTIONS The ADR44x family requires a 0.1 F capacitor on the input and the output for stability. While not required for operation, a 10 F capacitor at the input can help with line voltage transient performance. TP 1 VIN 10F + 2 0.1F NC 3 GND 4 ADR440/ ADR441/ ADR443/ ADR444/ ADR445 8 7 6 TP NC VOUT 0.1F 05428-034 TOP VIEW 5 TRIM (Not to Scale) VOUT = G (VP - R1 x I PTAT ) (1) NOTES 1. NC = NO CONNECT 2. TP = TEST PIN (DO NOT CONNECT) 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 option at the reference output. VIN IPTAT I1 I1 Figure 34. Basic Voltage Reference Configuration NOISE PERFORMANCE The noise generated by the ADR44x family of references is typically less than 1.4 V 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 V 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. ADR44x R2 * VP R3 VOUT 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 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 20 and Figure 21 show the turn-on and turn-off settling times for the ADR441. R1 *EXTRA CHANNEL IMPLANT VOUT = G (VP - R1 x IPTAT) GND Figure 33. Simplified Schematic Device 05428-033 Rev. A | Page 14 of 20 ADR440/ADR441/ADR443/ADR444/ADR445 APPLICATIONS 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. 0.1F 2 +VDD 2 VIN 0.1F ADR440/ ADR441/ ADR443/ ADR444/ ADR445 VOUT 6 GND 4 +5V 0.1F R1 R2 10k 10k +10V -5V R3 5k -10V VO = 0.5% 0.1F 05428-036 05428-037 VIN VOUT 6 Figure 36. ADR44x Bipolar Outputs ADR440/ ADR441/ ADR443/ ADR444/ ADR445 TRIM 5 GND 4 NEGATIVE REFERENCE RP 10k 05428-035 R1 100k R2 1k 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 can occur. Figure 37 shows how to connect the ADR44x and a standard operational amplifier, 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 temperature coefficient resistors to ensure accuracy. +VDD BIPOLAR OUTPUTS By connecting the output of the ADR44x to the inverting terminal of an operational amplifier, it is possible to obtain both positive and negative reference voltages. Care must be taken when choosing Resistor R1 and Resistor R2 (see Figure 36). 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 used over temperature; otherwise, differences exist between the two outputs. 2 VIN ADR440/ ADR441/ ADR443/ ADR444/ ADR445 6 VOUT GND 4 -VREF -VDD Figure 37. ADR44x Negative Reference VOUT is at virtual ground, and the negative reference is taken directly from the output of the operational amplifier. If the negative supply voltage is close to the reference output, the operational amplifier must be dual supply and have low offset and rail-to-rail capability. Rev. A | Page 15 of 20 ADR440/ADR441/ADR443/ADR444/ADR445 PROGRAMMABLE VOLTAGE SOURCE To obtain different voltages than those offered by the ADR44x, some extra components are needed. In Figure 38, two potentiometers are used to set the desired voltage, while 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. +VDD 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 39. 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 0.1F 2 VIN RSENSE 2 ADR440/ ADR441/ ADR443/ ADR444/ ADR445 VOUT 6 GND 4 VIN ADR440/ ADR441/ ADR443/ ADR444/ ADR445 VOUT 6 GND 4 0.1F ADJ VREF AD5259 R1 R2 10k 10k 05428-038 Figure 39. Programmable Current Source Figure 38. Programmable Voltage Source HIGH VOLTAGE FLOATING CURRENT SOURCE Use the circuit in Figure 40 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 SST111 VISHAY 2 For a completely programmable solution, replace the two potentiometers in Figure 38 with one Analog Devices dual digital potentiometer, offered with either an SPI(R) or an I2C(R) 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. Table 9. Digital Potentiometer Parts Part No. AD5251 AD5207 AD5242 AD5262 AD5282 AD5252 AD5232 AD5235 ADN2850 1 -VS Can also use a negative supply. Figure 40. Floating Current Source Adding a negative supply to the operational amplifier allows the user also 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. Rev. A | Page 16 of 20 05428-040 No. of Channels 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 No. of Positions 64.00 256.00 256.00 256.00 256.00 256.00 256.00 1024.00 1024.00 VIN ITF I2C SPI I2C SPI I2C I 2C SPI SPI SPI R (k) 1, 10, 50, 100 10, 50, 100 10, 100, 1M 20, 50, 200 20, 50, 100 1, 10, 50, 100 10, 50, 100 25, 250 25, 250 VDD1 5.5 5.5 5.5 15 15 5.5 5.5 5.5 5.5 ADR440/ ADR441/ ADR443/ ADR444/ ADR445 VOUT 6 OP90 GND 4 2N3904 05428-039 ILOAD ADR440/ADR441/ADR443/ADR444/ADR445 PRECISION OUTPUT REGULATOR (BOOSTED REFERENCE) VIN 2 VIN CIN 0.1F ADR440/ ADR441/ ADR443/ ADR444/ ADR445 VOUT 6 GND 4 2N7002 15V VO COUT 0.1F RL 200 -V CL 1F Figure 41. Boosted Output Reference Higher current drive capability can be obtained, without sacrificing accuracy, by using the circuit in Figure 41. 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. Rev. A | Page 17 of 20 05428-041 ADR440/ADR441/ADR443/ADR444/ADR445 OUTLINE DIMENSIONS 5.00 (0.1968) 4.80 (0.1890) 8 5 4 4.00 (0.1574) 3.80 (0.1497) 1 6.20 (0.2440) 5.80 (0.2284) 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) 1.75 (0.0688) 1.35 (0.0532) 0.50 (0.0196) x 45 0.25 (0.0099) 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 42. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches) 3.00 BSC 8 5 3.00 BSC 1 4.90 BSC 4 PIN 1 0.65 BSC 0.15 0.00 0.38 0.22 COPLANARITY 0.10 1.10 MAX 8 0 0.80 0.60 0.40 0.23 0.08 SEATING PLANE COMPLIANT TO JEDEC STANDARDS MO-187-AA Figure 43. 8-Lead Mini Small Outline Package [MSOP] (RM-8) Dimensions show in millimeters Rev. A | Page 18 of 20 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 (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 0.13 4 0.13 4 0.13 4 0.13 1.2 0.04 1.2 0.04 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 3 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 Branding R01 R01 R02 R02 R03 R03 R04 R04 R05 R05 Temperature Range -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C Package Option R-8 R-8 RM-8 RM-8 R-8 R-8 R-8 R-8 RM-8 RM-8 R-8 R-8 R-8 R-8 RM-8 RM-8 R-8 R-8 R-8 R-8 RM-8 RM-8 R-8 R-8 R-8 R-8 RM-8 RM-8 R-8 R-8 Z = Pb-free part. Rev. A | Page 19 of 20 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. (c)2006 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D05428-0-9/06(A) Rev. A | Page 20 of 20 |
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