Ultralow Noise, LDO XFET® Voltage References with Current Sink and Source ADR440/ADR441/ADR443/ADR444/ADR445 PIN CONFIGURATIONS Ultralow noise (0.1 Hz to 10 Hz) ADR440: 1 μV p-p ADR441: 1.2 μV p-p ADR443: 1.4 μV p-p ADR444: 1.8 μV p-p ADR445: 2.25 μV p-p Superb temperature coefficient: 3 ppm/°C (B Grade) 10 ppm/°C (A Grade) Low dropout operation: 500 mV Input range: (VOUT + 500 mV) to 18 V High output current: +10 mA/−5 mA Wide temperature range: −40°C to +125°C TP 1 VIN 2 NC 3 ADR44x TOP VIEW (Not to Scale) GND 4 8 TP 7 NC 6 VOUT 5 TRIM NC = NO CONNECT 05428-002 FEATURES Figure 1. 8-Lead SOIC (R) TP 1 ADR44x VIN 2 8 TP 7 NC 6 VOUT TOP VIEW GND 4 (Not to Scale) 5 TRIM NC = NO CONNECT 05428-001 NC 3 Figure 2. 8-Lead MSOP (RM) APPLICATIONS Precision data acquisition systems High resolution data converters Battery-powered instrumentations Portable medical instruments Industrial process control systems Precision instruments Optical control circuits GENERAL DESCRIPTION The ADR44x series is a family of XFET® voltage references featuring ultralow noise, high accuracy, and low temperature drift performance. Using ADI’s patented temperature drift curvature correction and XFET (eXtra implanted junction FET) technology, the ADR44x family’s voltage change vs. temperature nonlinearity is greatly minimized. The XFET references offer better noise performance than buried-Zener references, and XFET references operate off low supply headroom (0.5 V). This combination of features makes the ADR44x family ideally suited for precision signal conversion applications in high-end data acquisition systems, optical networks, and medical requirements. The ADR44x family has the capability to source up to 10 mA and sink up to 5 mA of output current. It also comes with a TRIM terminal to adjust the output voltage over a 0.5% range without compromising any performance. Offered in two electrical grades, the ADR44x family is available in the 8-lead SOIC and MSOP packages. All versions are specified over the extended industrial temperature range (−40oC to +125oC). Table 1. Selection Guide Model ADR440B ADR440A ADR441B ADR441A ADR443B ADR443A ADR444B ADR444A ADR445B ADR445A VOUT (V) 2.048 2.048 2.500 2.500 3.000 3.000 4.096 4.096 5.000 5.000 Accuracy (mV) ±1 ±3 ±1 ±3 ±1.2 ±4 ±1.6 ±5 ±2 ±6 Temperature Coefficient (ppm/°C) 3 10 3 10 3 10 3 10 3 10 Rev. 0 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 © 2005 Analog Devices, Inc. All rights reserved. ADR440/ADR441/ADR443/ADR444/ADR445 TABLE OF CONTENTS Features .............................................................................................. 1 Theory of Operation ...................................................................... 14 Applications....................................................................................... 1 Power Dissipation Considerations........................................... 14 Pin Configurations ........................................................................... 1 Basic Voltage Reference Connections ..................................... 14 General Description ......................................................................... 1 Noise Performance..................................................................... 14 Revision History ............................................................................... 2 Turn-On Time ............................................................................ 14 Specifications..................................................................................... 3 Applications..................................................................................... 15 ADR440—Electrical Characteristics.......................................... 3 Output Adjustment .................................................................... 15 ADR441—Electrical Characteristics.......................................... 4 Bipolar Outputs .......................................................................... 15 ADR443—Electrical Characteristics.......................................... 5 Negative Reference ..................................................................... 15 ADR444—Electrical Characteristics.......................................... 6 Programmable Voltage Source ................................................. 16 ADR445—Electrical Characteristics.......................................... 7 Programmable Current Source ................................................ 16 Absolute Maximum Ratings............................................................ 8 High Voltage Floating Current Source .................................... 16 Package Type ................................................................................. 8 Precision Output Regulator (Boosted Reference).................. 17 ESD Caution.................................................................................. 8 Outline Dimensions ....................................................................... 18 Typical Performance Characteristics ............................................. 9 Ordering Guide .......................................................................... 19 REVISION HISTORY 10/05—Revision 0: Initial Version Rev. 0 | Page 2 of 20 ADR440/ADR441/ADR443/ADR444/ADR445 SPECIFICATIONS ADR440—ELECTRICAL CHARACTERISTICS VIN = 3 V to 18 V; TA = 25°C; CIN, CBYPASS = 0.1 μF, unless otherwise noted. Table 2. Parameter OUTPUT VOLTAGE A Grade B Grade INITIAL ACCURACY A Grade B Grade TEMPERATURE DRIFT A Grade SOIC-8 MSOP-8 B Grade SOIC-8 LINE REGULATION LOAD REGULATION Symbol VO VO 1 Min Typ Max Unit 2.045 2.047 2.048 2.048 2.051 2.049 V V 3 0.15 1 0.05 mV % mV % 10 10 3 +20 ppm/°C ppm/°C ppm/°C ppm/V +50 ppm/mA +50 3.75 ppm/mA mA μV p-p nV/√Hz μs ppm ppm dB mA V mV VOERR VOERR TC VO TC VO TC VO ΔVO/ΔVIN ΔVO/ΔILOAD QUIESCENT CURRENT VOLTAGE NOISE VOLTAGE NOISE DENSITY TURN-ON SETTLING TIME LONG-TERM STABILITY 1 OUTPUT VOLTAGE HYSTERISIS RIPPLE REJECTION RATION SHORT CIRCUIT TO GND SUPPLY VOLTAGE OPERATING RANGE SUPPLY VOLTAGE HEADROOM Conditions ΔVO/ΔILOAD IIN eN p-p eN tR VO VO_HYS RRR ISC VIN VIN − VO −40°C < TA < +125°C −40°C < TA < +125°C −40°C < TA < +125°C VIN = 3 V to 18 V, −40°C < TA < +125°C ILOAD = 0 mA to 10 mA, VIN = 3.5 V −40°C < TA < +125°C ILOAD = 0 mA to −5 mA, VIN = 3.5 V −40°C < TA < +125°C No Load, −40°C < TA < +125°C 0.1 Hz to 10 Hz 1 kHz −20 2 2 1 +10 −50 −50 3 1 60 10 50 70 −75 27 1,000 Hours fIN = 10 kHz 3 500 18 The long-term stability specification is noncumulative. This drift in the subsequent 1,000-hour period is significantly lower than in the first 1,000-hour period. Rev. 0 | Page 3 of 20 ADR440/ADR441/ADR443/ADR444/ADR445 ADR441—ELECTRICAL CHARACTERISTICS VIN = 3 V to 18 V, TA = 25°C, unless otherwise noted. Table 3. Parameter OUTPUT VOLTAGE A Grade B Grade INITIAL ACCURACY A Grade B Grade Symbol VO VO Typ Max Unit 2.497 2.499 2.5 2.5 2.503 2.501 V V 3 0.12 1 0.04 mV % mV % 10 10 3 20 ppm/°C ppm/°C ppm/°C ppm/V +50 ppm/mA +50 3.75 ppm/mA mA μV p-p nV/√Hz μs ppm ppm dB mA V mV VOERR TC VO TC VO TC VO ΔVO/ΔVIN LOAD REGULATION ΔVO/ΔILOAD ΔVO/ΔILOAD 1 Min VOERR TEMPERATURE DRIFT A Grade SOIC-8 MSOP-8 B Grade SOIC-8 LINE REGULATION QUIESCENT CURRENT VOLTAGE NOISE VOLTAGE NOISE DENSITY TURN-ON SETTLING TIME LONG-TERM STABILITY 1 OUTPUT VOLTAGE HYSTERISIS RIPPLE REJECTION RATION SHORT CIRCUIT TO GND SUPPLY VOLTAGE OPERATING RANGE SUPPLY VOLTAGE HEADROOM Conditions IIN eN p-p eN tR VO VO_HYS RRR ISC VIN VIN − VO −40°C < TA < +125°C −40°C < TA < +125°C −40°C < TA < +125°C VIN = 3 V to 18 V, −40°C < TA < +125°C ILOAD = 0 mA to 10 mA, VIN = 4 V −40°C < TA < +125°C ILOAD = 0 mA to −5 mA, VIN = 4 V −40°C < TA < +125°C No Load, −40°C < TA < +125°C 0.1 Hz to 10 Hz 1 kHz 2 2 1 10 −50 −50 3 1.2 48 10 50 70 −75 27 1,000 Hours fIN = 10 kHz 3 500 18 The long-term stability specification is noncumulative. This drift in subsequent 1,000-hour period is significantly lower than in the first 1,000-hour period. Rev. 0 | Page 4 of 20 ADR440/ADR441/ADR443/ADR444/ADR445 ADR443—ELECTRICAL CHARACTERISTICS VIN = 3.5 V to 18 V, TA = 25°C, unless otherwise noted. Table 4. Parameter OUTPUT VOLTAGE A Grade B Grade INITIAL ACCURACY A Grade B Grade TEMPERATURE DRIFT A Grade SOIC-8 MSOP-8 B Grade SOIC-8 LINE REGULATION LOAD REGULATION Symbol VO VO TURN-ON SETTLING TIME LONG-TERM STABILITY 1 OUTPUT VOLTAGE HYSTERISIS RIPPLE REJECTION RATION SHORT CIRCUIT TO GND SUPPLY VOLTAGE OPERATING RANGE SUPPLY VOLTAGE HEADROOM 1 Min Typ Max Unit 2.996 2.9988 3.0 3.0 3.004 3.0012 V V 4 0.13 1.2 0.04 mV % mV % 10 10 3 20 ppm/°C ppm/°C ppm/°C ppm/V +50 ppm/mA +50 3.75 ppm/mA mA μV p-p VOERR VOERR TC VO TC VO TC VO ΔVO/ΔVIN ΔVO/ΔILOAD ΔVO/ΔILOAD QUIESCENT CURRENT VOLTAGE NOISE VOLTAGE NOISE DENSITY Conditions IIN eN p-p eN tR VO VO_HYS RRR ISC VIN VIN − VO −40°C < TA < +125°C −40°C < TA < +125°C −40°C < TA < +125°C VIN = 3.5 V to 18 V, −40°C < TA < +125°C ILOAD = 0 mA to 10 mA, VIN = 5 V −40°C < TA < +125°C ILOAD = 0 mA to −5 mA, VIN = 5 V −40°C < TA < +125°C No Load, −40°C < TA < +125°C 0.1 Hz to 10 Hz 2 2 1 10 −50 −50 3 1.4 1 kHz 64 10 50 70 −75 27 1,000 Hours fIN = 10 kHz 3.5 500 18 nV/√Hz μs ppm ppm dB mA V mV The long-term stability specification is noncumulative. This drift in the subsequent 1,000-hour period is significantly lower than in the first 1,000-hour period. Rev. 0 | Page 5 of 20 ADR440/ADR441/ADR443/ADR444/ADR445 ADR444—ELECTRICAL CHARACTERISTICS VIN = 4.6 V to 18 V, TA = 25°C, unless otherwise noted. Table 5. Parameter OUTPUT VOLTAGE A Grade B Grade INITIAL ACCURACY A Grade B Grade TEMPERATURE DRIFT A Grade SOIC-8 MSOP-8 B Grade SOIC-8 LINE REGULATION LOAD REGULATION Symbol VO VO 1 Min Typ Max Unit 4.091 4.0944 4.096 4.096 4.101 4.0976 V V 5 0.13 1.6 0.04 mV % mV % 10 10 3 20 ppm/°C ppm/°C ppm/°C ppm/V +50 ppm/mA +50 3.75 ppm/mA mA μV p-p nV/√Hz μs ppm ppm dB mA V mV VOERR VOERR TC VO TC VO TC VO ΔVO/ΔVIN ΔVO/ΔILOAD ΔVO/ΔILOAD QUIESCENT CURRENT VOLTAGE NOISE VOLTAGE NOISE DENSITY TURN-ON SETTLING TIME LONG-TERM STABILITY 1 OUTPUT VOLTAGE HYSTERISIS RIPPLE REJECTION RATION SHORT CIRCUIT TO GND SUPPLY VOLTAGE OPERATING RANGE SUPPLY VOLTAGE HEADROOM Conditions IIN eN p-p eN tR VO VO_HYS RRR ISC VIN VIN − VO −40°C < TA < +125°C −40°C < TA < +125°C −40°C < TA < +125vC VIN = 4.6 V to 18 V, −40°C < TA < +125°C ILOAD = 0 mA to 10 mA, VIN = 5.5 V −40°C < TA < +125°C ILOAD = 0 mA to −5 mA, VIN = 5.5 V −40°C < TA < +125°C No Load, −40°C < TA < +125°C 0.1 Hz to 10 Hz 1 kHz 2 2 1 10 −50 −50 3 1.8 64 10 50 70 −75 27 1,000 Hours fIN = 10 kHz 4.6 500 18 The long-term stability specification is noncumulative. This drift in the subsequent 1,000-hour period is significantly lower than in the first 1,000-hour period. Rev. 0 | Page 6 of 20 ADR440/ADR441/ADR443/ADR444/ADR445 ADR445—ELECTRICAL CHARACTERISTICS VIN = 5.5 V to 18 V, TA = 25°C unless otherwise noted. Table 6. Parameter OUTPUT VOLTAGE A Grade B Grade INITIAL ACCURACY A Grade B Grade TEMPERATURE DRIFT A Grade SOIC-8 MSOP-8 B Grade SOIC-8 LINE REGULATION LOAD REGULATION Symbol VO VO 1 Min Typ Max Unit 4.994 4.998 5.000 5.000 5.006 5.002 V V 6 0.12 2 0.04 mV % mV % 10 10 3 20 ppm/°C ppm/°C ppm/°C ppm/V +50 ppm/mA +50 3.75 ppm/mA mA μV p-p nV/√Hz μs ppm ppm dB mA V mV VOERR VOERR TC VO TC VO TC VO ΔVO/ΔVIN ΔVO/ΔILOAD ΔVO/ΔILOAD QUIESCENT CURRENT VOLTAGE NOISE VOLTAGE NOISE DENSITY TURN-ON SETTLING TIME LONG-TERM STABILITY 1 OUTPUT VOLTAGE HYSTERISIS RIPPLE REJECTION RATION SHORT CIRCUIT TO GND SUPPLY VOLTAGE OPERATING RANGE SUPPLY VOLTAGE HEADROOM Conditions IIN eN p-p eN tR VO VO_HYS RRR ISC VIN VIN − VO −40°C < TA < +125°C −40°C < TA < +125°C −40°C < TA < +125°C VIN = 5.5 V to 18 V, −40°C < TA < +125°C ILOAD = 0 mA to 10 mA, VIN = 6.5 V −40°C < TA < +125°C ILOAD = 0 mA to −5 mA, VIN = 6.5 V −40°C < TA < +125°C No Load, −40°C < TA < +125°C 0.1 Hz to 10 Hz 1 kHz 2 2 1 10 −50 −50 3 2.25 64 10 50 70 –75 27 1,000 Hours fIN = 10 kHz 5.5 500 18 The long-term stability specification is noncumulative. This drift in the subsequent 1,000-hour period is significantly lower than in the first 1,000-hour period. Rev. 0 | Page 7 of 20 ADR440/ADR441/ADR443/ADR444/ADR445 ABSOLUTE MAXIMUM RATINGS At 25°C, unless otherwise noted. Table 7. Parameter Supply Voltage Output Short-Circuit Duration to GND Storage Temperature Range R, RM Packages Operating Temperature Range Junction Temperature Range Lead Temperature Range (Soldering, 60 sec) Rating 20 V Indefinite −65°C to +125°C −40°C to +125°C −65°C to +150°C 300°C Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. PACKAGE TYPE Table 8. Package Type 8-Lead SOIC (R) 8-Lead MSOP (RM) 1 θJA 1 130 190 θJC 43 Unit °C/W °C/W θJA is specified for worst-case conditions (device soldered in circuit board for surface mount packages). Contact sales for the latest information of release dates. ESD CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. Rev. 0 | Page 8 of 20 ADR440/ADR441/ADR443/ADR444/ADR445 TYPICAL PERFORMANCE CHARACTERISTICS VIN = 7V, TA = 25oC; CIN, CBYPASS = 0.1 μF; unless otherwise noted. 2.5020 4.0 SUPPLY CURRENT (mA) OUTPUT VOLTAGE (V) 2.5015 2.5010 2.5005 2.5000 3.5 +125°C +25°C 3.0 –40°C 2.5 –25 –10 5 20 35 50 65 TEMPERATURE (°C) 80 95 110 05428-006 2.4990 –40 05428-003 2.4995 2.0 4 125 6 8 10 12 14 INPUT VOLTAGE (V) 16 18 Figure 6. ADR441 Supply Current vs. Input Voltage Figure 3. ADR441 VOUT vs. Temperature 3.0020 4.0 3.0015 VOUT (V) 3.0005 3.0000 2.9995 2.9990 2.9980 –40 05428-004 2.9985 –25 –10 5 20 35 50 65 TEMPERATURE (°C) 80 95 110 3.5 3.0 2.5 2.0 –40 125 Figure 4. ADR444 VOUT vs. Temperature 05428-007 SUPPLY CURRENT (mA) 3.0010 –25 –10 5 20 35 50 65 TEMPERATURE (°C) 80 95 110 125 Figure 7. ADR441 Supply Current vs. Temperature 4.0980 3.5 4.0975 3.4 3.3 SUPPLY CURRENT (mA) 4.0970 4.0960 4.0955 4.0950 3.2 3.1 +125°C 3.0 2.9 +25°C 2.8 2.7 4.0940 –40 –25 –10 5 20 35 50 65 TEMPERATURE (°C) 80 95 110 –40°C 05428-008 4.0945 05428-005 VOUT (V) 4.0965 2.6 2.5 5.3 125 Figure 5. ADR445 VOUT vs. Temperature 7.3 9.3 11.3 13.3 15.3 INPUT VOLTAGE (V) 17.3 Figure 8. ADR445 Supply Current vs. Input Voltage Rev. 0 | Page 9 of 20 19.3 ADR440/ADR441/ADR443/ADR444/ADR445 3.25 7 LINE REGULATIOIN (ppm/V) QUIESCENT CURRENT (mA) 6 3.15 3.05 2.95 5 4 3 2 2.85 –25 –10 5 20 35 50 65 TEMPERATURE (°C) 80 95 110 0 –40 125 Figure 9. ADR445 Quiescent Current vs. Temperature 05428-012 05428-009 2.75 –40 1 –25 –10 5 20 35 50 65 TEMPERATURE (°C) 80 95 110 125 Figure 12. ADR445 Line Regulation vs. Temperature 10 50 6 4 0 –40 05428-010 2 –25 –10 5 20 35 50 65 TEMPERATURE (°C) 80 95 110 30 20 0mA TO +10mA LOAD 10 0 –10 0mA TO –5mA LOAD –20 –30 –40 –50 –40 125 Figure 10. ADR441 Line Regulation vs. Temperature –25 –10 5 20 35 50 65 TEMPERATURE (°C) 80 95 110 125 Figure 13. ADR445 Load Regulation vs. Temperature 60 0.7 0.6 DIFFERENTIAL VOLTAGE (V) 55 50 IL = 0mA TO 10 mA 45 VIN = 6V 40 35 30 –40 –25 –10 5 20 35 50 65 TEMPERATURE (°C) 80 95 110 +125°C 0.5 0.4 +25°C 0.3 –40°C 0.2 0.1 0 –10 125 05428-014 VIN = 18V 05428-011 LOAD REGULATION (ppm/mA) 05428-013 LOAD REGULATION (ppm/mA) LINE REGULATION (ppm/V) 40 8 –5 0 LOAD CURRENT (mA) 5 Figure 14. ADR441 Minimum Input/Output Differential Voltage vs. Load Current Figure 11. ADR441 Load Regulation vs. Temperature Rev. 0 | Page 10 of 20 10 ADR440/ADR441/ADR443/ADR444/ADR445 0.5 CIN, COUT = 0.1μF NO LOAD MINIMUM HEADROOM (V) 0.4 VIN = 5V/DIV 0.3 0.2 0.1 –25 –10 5 20 35 50 65 TEMPERATURE (°C) 80 95 110 TIME = 10μs/DIV 125 Figure 15. ADR441 Minimum Headroom vs. Temperature 05428-018 05428-015 0 –40 VOUT = 1V/DIV Figure 18. ADR441 Turn-On Response 1.0 CIN, COUT = 0.1μF 0.8 +125°C 0.7 VIN = 5V/DIV 0.6 0.5 +25°C 0.4 –40°C 0.3 0.2 05428-016 0.1 0 –5 0 5 LOAD CURRENT (mA) VOUT = 1V/DIV 10 05428-019 DIFFERENTIAL VOLTAGE (V) 0.9 TIME = 200μs/DIV Figure 19. ADR441 Turn-Off Response Figure 16. ADR445 Minimum Input/Output Differential Voltage vs. Load Current CIN = 0.1μF COUT = 10μF 0.5 NO LOAD VIN = 5V/DIV 0.3 0.2 0 –40 –25 –10 5 20 35 50 65 TEMPERATURE (°C) 80 95 110 TIME = 200μs/DIV 125 Figure 20. ADR441 Turn-On Response Figure 17. ADR445 Minimum Headroom vs. Temperature Rev. 0 | Page 11 of 20 05428-020 VOUT = 1V/DIV 0.1 05428-017 MINIMUM HEADROOM (V) 0.4 ADR440/ADR441/ADR443/ADR444/ADR445 CIN = 0.1μF COUT = 10μF 2V/DIV 4V 1μV/DIV CH1 p-p 1.18μV TIME = 1s/DIV Figure 21. ADR441 Line Transient Response 05428-024 100μs/DIV 05428-021 2mV/DIV Figure 24. ADR441 0.1 Hz to 10.0 Hz Voltage Noise CIN, COUT = 0.1μF LOAD OFF LOAD ON 50μV/DIV CH1 p-p 49μV 1 05428-025 200μs/DIV 05428-022 5mV/DIV TIME = 1s/DIV Figure 22. ADR441 Load Transient Response Figure 25. ADR441 10 Hz to 10 kHz Voltage Noise CIN = 0.1μF COUT = 10μF LOAD OFF LOAD ON 1μV/DIV CH1 p-p 2.24μV TIME = 1s/DIV Figure 26. ADR445 0.1 Hz to 10.0 Hz Voltage Noise Figure 23. ADR441 Load Transient Response Rev. 0 | Page 12 of 20 05428-026 200μs/DIV 05428-023 5mV/DIV ADR440/ADR441/ADR443/ADR444/ADR445 10 9 50μV/DIV CH1 p-p 66μV OUTPUT IMPEDANCE (Ω) 8 7 ADR445 6 5 ADR443 4 3 ADR441 1 0 05428-027 TIME = 1s/DIV 100 1k FREQUENCY (Hz) 10k 100k Figure 29. Output Impedance vs. Frequency Figure 27. ADR445 10 Hz to 10 kHz Voltage Noise 16 0 –10 12 –20 RIPPLE REJECTION (dB) 14 10 8 6 4 –30 –40 –50 –60 –70 05428-028 –90 –100 150 130 90 110 70 50 30 10 –10 –30 –50 –70 –90 –110 –130 0 05428-030 –80 2 –150 NUMBER OF PARTS 10 05428-029 2 DEVIATION (PPM) 100 1k 10k FREQUENCY (Hz) 100k Figure 30. Ripple Rejection vs. Frequency Figure 28. ADR441 Typical Hysteresis Rev. 0 | Page 13 of 20 1M ADR440/ADR441/ADR443/ADR444/ADR445 THEORY OF OPERATION The intrinsic reference voltage is around 0.5 V with a negative temperature coefficient of about –120 ppm/°C. This slope is essentially constant to the dielectric constant of silicon and can be closely compensated for by adding a correction term generated in the same fashion as the proportional-to-temperature (PTAT) term used to compensate band gap references. The advantage of an XFET reference is the correction term is approximately 20 times lower and requires less correction than a band gap reference. This results in much lower noise, because most of the noise of a band gap reference results from the temperature compensation circuitry. POWER DISSIPATION CONSIDERATIONS The ADR44x family of references is guaranteed to deliver load currents to 10 mA with an input voltage that ranges from 2.6 V to 18 V. When these devices are used in applications at higher currents, users should use the following equation to account for the temperature effects due to the power dissipation increases. TJ = PD × θ JA + TA where: TJ and TA are the junction and ambient temperatures. PD is the device power dissipation. θJA is the device package thermal resistance. BASIC VOLTAGE REFERENCE CONNECTIONS The ADR44x family requires a 0.1 μF capacitor on the input and output for stability. While not required for operation, a 10 μF capacitor at the input can help with line voltage transient performance. TP 1 VIN ) 2 + Figure 31 shows the basic topology of the ADR44x series. The temperature correction term is provided by a current source with a value designed to be proportional to absolute temperature. The general equation is VOUT = G × (ΔVP − R1 × I PTAT (2) 10μF 0.1μF ADR44x 8 TP 7 NIC OUTPUT NIC 3 TOP VIEW 6 (Not to Scale) 4 5 TRIM NOTES 1. NIC = NO INTERNAL CONNECTION 2. TP = TEST PIN (DO NOT CONNECT) (1) 0.1μF 05428-034 The ADR44x series of references uses a new reference generation technique known as XFET (eXtra implanted junction FET). This technique yields a reference with low dropout, good thermal hysteresis, and exceptionally low noise. The core of the XFET reference consists of two junction field-effect transistors (JFETs), one of which has an extra channel implant to raise its pinch-off voltage. By running the two JFETs at the same drain current, the difference in pinch-off voltage can be amplified and used to form a highly stable voltage reference. Figure 32. Basic Voltage Reference Configuration where: G is the gain of the reciprocal of the divider ratio. ΔVP is the difference in pinch-off voltage between the two JFETs. IPTAT is the positive temperature coefficient correction current. ADR44x devices are created by on-chip adjustment of R2 and R3 to achieve the different voltage option at the reference output. VIN I1 NOISE PERFORMANCE The noise generated by the ADR44x family of references is typically less than 1.4 μV p-p over the 0.1 Hz to 10.0 Hz band for ADR440, ADR441, and ADR443. Figure 24 shows the 0.1 Hz to 10 Hz noise of the ADR441, which is only 1.2 μV p-p. The noise measurement is made with a band-pass filter made of a 2pole high-pass filter with a corner frequency at 0.1 Hz and a 2pole low-pass filter with a corner frequency at 10.0 Hz. I1 TURN-ON TIME ADR44x IPTAT VOUT R2 1 R1 R3 1EXTRA CHANNEL IMPLANT VOUT = G(ΔVP – R1 × IPTAT) GND 05428-033 ΔVP Upon application of power (cold start), the time required for the output voltage to reach its final value within a specified error band is defined as the turn-on settling time. Two components normally associated with this are the time for the active circuits to settle, and the time for the thermal gradients on the chip to stabilize. Figure 18 and Figure 19 show the turn-on and turn-off settling times for the ADR441. Figure 31. Simplified Schematic Device Rev. 0 | Page 14 of 20 ADR440/ADR441/ADR443/ADR444/ADR445 +VDD APPLICATIONS OUTPUT ADJUSTMENT 2 VIN The ADR44x family features a TRIM pin that allows the user to adjust the output voltage of the part over a limited range. This allows both errors from the reference and overall system errors to be trimmed out by connecting a potentiometer between the output and ground, with the wiper connected to the TRIM pin. Figure 33 shows the optimal trim configuration. R1 allows fine adjustment of the output and is not always required. RP should be sufficiently large so that the maximum output current from the ADR44x is not exceeded. 0.1μF ADR445 VOUT 6 +5V 0.1μF GND R1 R2 10kΩ 10kΩ 4 +10V 05428-036 –5V R3 5kΩ –10V Figure 34. ADR 44x Bipolar Outputs 0.1μF NEGATIVE REFERENCE 2 VIN R1 RP R2 05428-035 4 Figure 33. ADR44x Trim Function Using the trim function had a negligible effect on the temperature performance of the ADR44x family. However, all resistors used need to be low temperature coefficient resistors, or errors can occur. +VDD 2 VIN 6 BIPOLAR OUTPUTS By connecting the output of the ADR44x to the inverting terminal of an op amp, it is possible to obtain both positive and negative reference voltages. Care must be taken when choosing Resistor R1 and Resistor R2 (see Figure 34). They must be matched as closely as possible to ensure minimal differences between the negative and positive outputs. In addition, care must be taken to ensure performance over temperature. Use low temperature coefficient resistors if the circuit is to be used over temperature; otherwise, differences will exist between the two outputs. VOUT ADR44x GND 4 –VREF –VDD 05428-037 0.1μF ADR44x TRIM 5 GND Figure 35 shows how to connect the ADR44x and a standard op amp, such as the OP1177, to provide negative voltage. This configuration provides two main advantages: First, it only requires two devices; therefore, it does not require excessive board space. Second, and more importantly, it does not require any external resistors. This means the performance of this circuit does not rely on choosing low TC resistors to ensure accuracy. VO = ±0.5% VOUT 6 Figure 35. Negative Reference VOUT is at virtual ground, and the negative reference is taken directly from the output of the op amp. If the negative supply voltage is close to the reference output, the op amp must be dual supply and have low offset and rail-to-rail capability. Rev. 0 | Page 15 of 20 ADR440/ADR441/ADR443/ADR444/ADR445 PROGRAMMABLE VOLTAGE SOURCE PROGRAMMABLE CURRENT SOURCE To obtain different voltages than those offered by the ADR44x, some extra components are needed. In Figure 36, two potentiometers are used to set the desired voltage, while the buffering amplifier provides current drive. The potentiometer connected between VOUT and ground, with its wiper connected to the noninverting input of the op amp, takes care of coarse trim. The second potentiometer, with its wiper connected to the trim terminal of the ADR44x, is used for fine adjustment. Resolution depends on the end-to-end resistance value and the resolution of the selected potentiometer. It is possible to build a programmable current source using a similar setup as the programmable voltage source, as shown in Figure 37. The constant voltage on the gate of the transistor sets the current through the load. Varying the voltage on the gate changes the current. This circuit does not require a dual digital potentiometer. VCC 0.1μF 2 VIN RSENSE VOUT 6 +VDD GND 0.1μF 4 2 AD5259 VIN LOAD VOUT 6 R1 R2 10kΩ 10kΩ Figure 37. Programmable Current Source 05428-038 4 HIGH VOLTAGE FLOATING CURRENT SOURCE Figure 36. Programmable Voltage Source For a completely programmable solution, replace the two potentiometers in Figure 36 with one of ADI’s dual digital potentiometers, which offer either SPI® or I2C interfaces. These interfaces set the position of the wiper on both potentiometers and allow the output voltage to be set. Table 9 lists compatible ADI digital potentiometers. Use the circuit in Figure 38 to generate a floating current source with minimal self-heating. This particular configuration can operate on high supply voltages determined by the breakdown voltage of the N-channel JFET. Table 9. Digital Potentiometer Parts Part No. AD5251 AD5207 AD5242 AD5262 AD5282 AD5252 AD5232 AD5235 ADN2850 1 No. Chan 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 No. Pos 64.00 256.00 256.00 256.00 256.00 256.00 256.00 1024.00 1024.00 ITF I2C SPI I2C SPI I2C I2C SPI SPI SPI +VS SST111 VISHAY 2 R (kΩ) 1, 10, 50, 100 10, 50, 100 10, 100, 1M 20, 50, 200 20, 50, 100 1, 10, 50, 200 10, 50, 100 25, 250 25, 250 VDD1 5.5 5.5 5.5 15 15 5.5 5.5 5.5 5.5 Can also use a negative supply. By adding a negative supply to the op amp, it is possible for the user to also produce a negative programmable reference by connecting the reference output to the inverting terminal of the op amp. Choose feedback resistors to minimize errors over temperature. Rev. 0 | Page 16 of 20 VIN ADR44x VOUT 6 OP90 2N3904 GND 4 –VS Figure 38. Floating Current Source 05428-040 GND 05428-039 ADJ VREF ADR445 ADR440/ADR441/ADR443/ADR444/ADR445 PRECISION OUTPUT REGULATOR (BOOSTED REFERENCE) VIN 2 VIN 15V ADR44x VOUT 6 GND 4 VO COUT 0.1μF RL 200Ω CL 1μF –V 05428-041 CIN 0.1μF 2N7002 Figure 39. Boosted Output Reference Higher current drive capability without sacrificing accuracy can be obtained using the circuit in Figure 39. The op amp regulates the MOSFET turn-on, which forces VO to equal the VREF. Current is then drawn from VIN, which allows increased current drive capability. The circuit allows a 50 mA load; if higher current drive is required, use a larger MOSFET. For fast transient response, add a buffer at VO to aid with capacitive loading. Rev. 0 | Page 17 of 20 ADR440/ADR441/ADR443/ADR444/ADR445 OUTLINE DIMENSIONS 5.00 (0.1968) 4.80 (0.1890) 8 5 4.00 (0.1574) 3.80 (0.1497) 1 4 6.20 (0.2440) 5.80 (0.2284) 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) 0.50 (0.0196) × 45° 0.25 (0.0099) 1.75 (0.0688) 1.35 (0.0532) 0.51 (0.0201) COPLANARITY SEATING 0.31 (0.0122) 0.10 PLANE 8° 0.25 (0.0098) 0° 1.27 (0.0500) 0.40 (0.0157) 0.17 (0.0067) COMPLIANT TO JEDEC STANDARDS MS-012-AA CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN Figure 40. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches) 3.00 BSC 8 3.00 BSC 1 5 4.90 BSC 4 PIN 1 0.65 BSC 1.10 MAX 0.15 0.00 0.38 0.22 COPLANARITY 0.10 0.23 0.08 8° 0° SEATING PLANE COMPLIANT TO JEDEC STANDARDS MO-187-AA Figure 41. 8-Lead Mini Small Outline Package [MSOP} (RM-8) Dimensions show in millimeters Rev. 0 | Page 18 of 20 0.80 0.60 0.40 ADR440/ADR441/ADR443/ADR444/ADR445 ORDERING GUIDE Model ADR440ARZ 1 ADR440ARZ-REEL71 ADR440ARMZ1 ADR440ARMZ-REEL71 ADR440BRZ1 ADR440BRZ-REEL71 ADR441ARZ1 ADR441ARZ-REEL71 ADR441ARMZ1 ADR441ARMZ-REEL71 ADR441BRZ1 ADR441BRZ-REEL71 ADR443ARZ1 ADR443ARZ-REEL71 ADR443ARMZ1 ADR443ARMZ-REEL71 ADR443BRZ1 ADR443BRZ-REEL71 ADR444ARZ1 ADR444ARZ-REEL71 ADR444ARMZ1 ADR444ARMZ-REEL71 ADR444BRZ1 ADR444BRZ-REEL71 ADR445ARZ1 ADR445ARZ-REEL71 ADR445ARMZ1 ADR445ARMZ-REEL71 ADR445BRZ1 ADR445BRZ-REEL71 1 Output Voltage (VO) V 2.048 2.048 2.048 2.048 2.048 2.048 2.500 2.500 2.500 2.500 2.500 2.500 3.000 3.000 3.000 3.000 3.000 3.000 4.096 4.096 4.096 4.096 4.096 4.096 5.000 5.000 5.000 5.000 5.000 5.000 Initial Accuracy (mV) (%) 3 0.15 3 0.15 3 0.15 3 0.15 1 0.05 1 0.05 3 0.12 3 0.12 3 0.12 3 0.12 1 0.04 1 0.04 4 0.12 4 0.12 4 0.12 4 0.12 1.2 0.05 1.2 0.05 5 0.13 5 0.13 5 0.13 5 0.13 1.6 0.04 1.6 0.04 6 0.12 6 0.12 6 0.12 6 0.12 2 0.04 2 0.04 Temperature Coefficient Package (ppm/°C) 10 10 10 10 3 3 10 10 10 10 3 3 10 10 10 10 3F 3 10 10 10 10 3 3 10 10 10 10 3 3 Package Description 8-lead SOIC_N 8-Lead SOIC_N 8-Lead MSOP 8-Lead MSOP 8-lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead MSOP 8-Lead MSOP 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead MSOP 8-Lead MSOP 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead MSOP 8-Lead MSOP 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead MSOP 8-Lead MSOP 8-Lead SOIC_N 8-Lead SOIC_N Z = Pb-free part. Rev. 0 | Page 19 of 20 Branding R01 R01 R02 R02 R03 R03 R04 R04 R05 R05 Temperature Range (°C) –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40°C to +125°C –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40 to +125 –40 to +125 Ordering Quantity 98 1,000 98 1,000 98 1,000 98 1,000 98 1,000 98 1,000 98 1,000 98 1,000 98 1,000 98 1,000 98 1,000 98 1,000 98 1,000 98 1,000 98 1,000 ADR440/ADR441/ADR443/ADR444/ADR445 NOTES Purchase of licensed I2C components of Analog Devices or one of its sublicensed Associated Companies conveys a license for the purchaser under the Philips I2C Patent Rights to use these components in an I2C system, provided that the system conforms to the I2C Standard Specification as defined by Philips. © 2005 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D05428-0-10/05(0) Rev. 0 | Page 20 of 20