Low Noise, Micropower 5.0 V Precision Voltage Reference ADR293 FEATURES PIN CONFIGURATIONS 6.0 V to 15 V supply range Supply current: 15 A maximum Low noise: 15 V p-p typical (0.1 Hz to 10 Hz) High output current: 5 mA Temperature range: -40C to +125C Pin-compatible with the REF02/REF19x NC 1 VIN 2 8 ADR293 NC NC TOP VIEW 6 VOUT (Not to Scale) 5 NC GND 4 7 NC = NO CONNECT 00164-001 NC 3 Figure 1. 8-Lead Narrow Body SOIC (R-8) Portable instrumentation Precision reference for 5 V systems ADC and DAC reference Solar-powered applications Loop-current powered instruments NC 1 8 NC VIN 2 ADR293 7 NC NC 3 TOP VIEW (Not to Scale) 6 VOUT GND 4 5 NC NC = NO CONNECT 00164-002 APPLICATIONS Figure 2. 8-Lead TSSOP (RU-8) GENERAL DESCRIPTION The ADR293 is a low noise, micropower precision voltage reference that utilizes an XFET(R) (eXtra implanted junction FET) reference circuit. The XFET architecture offers significant performance improvements over traditional band gap and buried Zener-based references. Improvements include one quarter the voltage noise output of band gap references operating at the same current, very low and ultralinear temperature drift, low thermal hysteresis, and excellent longterm stability. The ADR293 is a series voltage reference providing stable and accurate output voltage from a 6.0 V supply. Quiescent current is only 15 A maximum, making this device ideal for battery powered instrumentation. Three electrical grades are available offering initial output accuracy of 3 mV, 6 mV, and 10 mV. Temperature coefficients for the three grades are 8 ppm/C, 15 ppm/C, and 25 ppm/C maximum. Line regulation and load regulation are typically 30 ppm/V and 30 ppm/mA, respectively, maintaining the reference's overall high performance. The ADR293 is specified over the extended industrial temperature range of -40C to +125C. This device is available in the 8-lead SOIC and 8-lead TSSOP packages. Table 1. ADR29x Products Device ADR291 ADR292 ADR293 Output Voltage (V) 2.500 4.096 5.000 Initial Accuracy (%) 0.08, 0.12, 0.24 0.07, 0.10, 0.15 0.06, 0.12, 0.20 Temperature Coefficient (ppm/C max) 8, 15, 25 8, 15, 25 8, 15, 25 Rev. D 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)2001-2011 Analog Devices, Inc. All rights reserved. ADR293 TABLE OF CONTENTS Features .............................................................................................. 1 Terminology .......................................................................................9 Applications ....................................................................................... 1 Theory of Operation ...................................................................... 10 Pin Configurations ........................................................................... 1 Device Power Dissipation Considerations .............................. 10 General Description ......................................................................... 1 Basic Voltage Reference Connections ..................................... 10 Revision History ............................................................................... 2 Noise Performance ..................................................................... 10 Specifications..................................................................................... 3 Turn-On Time ............................................................................ 10 Electrical Specifications ............................................................... 3 Applications..................................................................................... 11 Absolute Maximum Ratings............................................................ 5 Kelvin Connections .................................................................... 11 Thermal Resistance ...................................................................... 5 Voltage Regulator for Portable Equipment ............................. 11 ESD Caution .................................................................................. 5 Outline Dimensions ....................................................................... 12 Typical Performance Characteristics ............................................. 6 Ordering Guide .......................................................................... 12 REVISION HISTORY 5/11--Rev. C to Rev. D Delete Negative Precision Reference Without Precision Resistors Section ............................................................................. 11 Delete Figure 23 and Figure 24, Renumbered Sequentially ...... 11 9/10--Rev. B to Rev. C Changes to Table 2 and Table 3 ....................................................... 3 Changes to Table 4 ............................................................................ 4 Changes to Figure 10, Figure 11, Figure 13 ................................... 7 Changes to Captions for Figure 17 to Figure 19 ........................... 8 6/07--Rev. A to Rev. B Updated Format .................................................................. Universal Changes to Table 1.............................................................................1 Updated Outline Dimensions ....................................................... 13 Changes to Ordering Guide .......................................................... 13 3/01--Rev. 0 to Rev. A Rev. D | Page 2 of 12 ADR293 SPECIFICATIONS ELECTRICAL SPECIFICATIONS VS = 6.0 V, TA = 25C, unless otherwise noted. Table 2. Parameter OUTPUT VOLTAGE E Grade F Grade G Grade INITIAL ACCURACY E Grade Symbol VOUT Conditions IOUT = 0 mA Min Typ Max Unit 4.997 4.994 4.990 5.000 5.000 5.000 5.003 5.006 5.010 V V V +3 0.06 +6 0.12 +10 0.20 mV % mV % mV % 30 40 100 150 ppm/V ppm/V 30 40 50 15 640 100 150 ppm/mA ppm/mA ppm V p-p nV/Hz IOUT = 0 mA -3 F Grade -6 G Grade -10 LINE REGULATION E, F Grades G Grade LOAD REGULATION E, F Grades G Grade LONG-TERM STABILITY VOLTAGE NOISE VOLTAGE NOISE DENSITY VOUT /VIN VOUT /ILOAD VOUT eN p-p eN 6.0 V to 15 V, IOUT = 0 mA VS = 6.0 V, IOUT = 0 mA to 5 mA After 1000 hours of operation @ 125C f = 0.1 Hz to 10 Hz f = 1 kHz VS = 6.0 V, TA = -25C to +85C, unless otherwise noted. Table 3. Parameter TEMPERATURE COEFFICIENT E Grade F Grade G Grade LINE REGULATION E, F Grades G Grade LOAD REGULATION E, F Grades G Grade Symbol TCVOUT VOUT/VIN VOUT/ILOAD Conditions IOUT = 0 mA Min Typ Max Unit 3 5 10 8 15 25 ppm/C ppm/C ppm/C 35 50 150 200 ppm/V ppm/V 20 30 150 200 ppm/mA ppm/mA 6.0 V to 15 V, IOUT = 0 mA VS = 6.0 V, IOUT = 0 mA to 5 mA Rev. D | Page 3 of 12 ADR293 VS = 6.0 V, TA = -40C to +125C, unless otherwise noted. Table 4. Parameter TEMPERATURE COEFFICIENT E Grade F Grade G Grade LINE REGULATION E, F Grades G Grade LOAD REGULATION E, F Grades G Grade SUPPLY CURRENT THERMAL HYSTERESIS Symbol TCVOUT VOUT/VIN VOUT/ILOAD IS VOUT-HYS Conditions IOUT = 0 mA Min Typ Max Unit 3 5 10 10 20 30 ppm/C ppm/C ppm/C 40 70 200 250 ppm/V ppm/V @ 25C 20 30 11 200 300 15 ppm/mA ppm/mA A 20 8-lead SOIC_N 8-lead TSSOP 15 72 157 A ppm ppm 6.0 V to 15 V, IOUT = 0 mA VS = 6.0 V, IOUT = 0 mA to 5 mA Rev. D | Page 4 of 12 ADR293 ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE Table 5. Parameter Supply Voltage Output Short-Circuit Duration to GND Storage Temperature Range Operating Temperature Range Junction Temperature Range Lead Temperature (Soldering, 60 sec) Rating 18 V Indefinite -65C to +150C -40C to +125C -65C to +150C 300C 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. JA is specified for worst-case conditions; that is, JA is specified for the device in socket testing. In practice, JA is specified for the device soldered in a circuit board. Table 6. Thermal Resistance Package Type 8-Lead SOIC_N (R-8) 8-Lead TSSOP (RU-8) ESD CAUTION Rev. D | Page 5 of 12 JA 158 240 JC 43 43 Unit C/W C/W ADR293 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25C, unless otherwise noted. 5.006 100 VS = 6V 3 TYPICAL PARTS VS = 6V TO 15V LINE REGULATION (ppm/V) 5.002 5.000 4.998 80 60 40 20 4.996 -25 0 25 50 TEMPERATURE (C) 75 100 125 0 -50 00164-003 4.994 -50 Figure 3. VOUT vs. Temperature 0 25 50 TEMPERATURE (C) 75 100 125 Figure 6. Line Regulation vs. Temperature 100 16 14 TA = +125C 12 TA = +25C IOUT = 0mA VS = 6V TO 9V LINE REGULATION (ppm/V) SUPPLY CURRENT (A) -25 00164-006 OUTPUT VOLTAGE (V) 5.004 10 TA = -40C 8 6 4 80 60 40 20 2 4 6 8 10 INPUT VOLTAGE (V) 12 14 16 0 -50 0 25 50 TEMPERATURE (C) 75 100 125 5.0 Figure 7. Line Regulation vs. Temperature Figure 4. Supply Current vs. Input Voltage 0.7 16 VS = 6V 0.6 DIFFERENTIAL VOLTAGE (V) 14 12 10 8 0.5 TA = +125C 0.4 TA = +25C 0.3 TA = -40C 0.2 0.1 6 -50 -25 0 25 50 TEMPERATURE (C) 75 100 Figure 5. Supply Current vs. Temperature 125 0 00164-005 SUPPLY CURRENT (A) -25 00164-007 0 00164-008 0 00164-004 2 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 LOAD CURRENT (mA) 4.0 4.5 Figure 8. Minimum Input/Output Voltage Differential vs. Load Current Rev. D | Page 6 of 12 ADR293 120 200 VS = 6V 100 160 RIPPLE REJECTION (dB) LOAD REGULATION (ppm/mA) VS = 6V 120 80 IOUT = 5mA 80 60 40 40 20 -25 0 25 50 TEMPERATURE (C) 75 100 125 0 10 00164-009 0 -50 100 FREQUENCY (Hz) 1k 00164-012 IOUT = 1mA Figure 12. Ripple Rejection vs. Frequency Figure 9. Load Regulation vs. Temperature 100 2 VS = 6V IL = 0mA TA = +25C 0 -1 OUTPUT IMPEDANCE () VOUT FROM NOMINAL (mV) 1 TA = +125C TA = -40C -2 10 1 SOURCING LOAD CURRENT (mA) 10 1 10 00164-010 -4 0.1 100 1k FREQUENCY (Hz) 10k 00164-013 -3 Figure 13. Output Impedance vs. Frequency Figure 10. VOUT from Nominal vs. Load Current 1k 1s/DIV 100 10 100 FREQUENCY (Hz) 1k Figure 14. 0.1 Hz to 10 Hz Noise Figure 11. Voltage Noise Density vs. Frequency Rev. D | Page 7 of 12 00164-014 10V p-p 00164-011 VOLTAGE NOISE DENSITY (nV/ Hz) VIN = 15V TA = 25C ADR293 II = 5mA CL = 1nF IL = 5mA 5V/DIV 00164-018 50s/DIV 00164-015 2V/DIV 1ms/DIV Figure 15. Turn-On Time Figure 18. Load Transient Response IL = 5mA II = 5mA CL = 100nF 5V/DIV 00164-019 50s/DIV 00164-016 2V/DIV 1ms/DIV Figure 16. Turn-Off Time Figure 19. Load Transient Response 18 TEMPERATURE +25C -40C +85C +25C 16 FREQUENCY IN NUMBER OF UNITS IL = 5mA 14 12 10 8 6 4 0 -200 -160 -120 -80 Figure 17. Load Transient Response -40 0 40 80 120 VOUT DEVIATION (ppm) 160 200 Figure 20. Typical Hysteresis for the ADR29x Product Rev. D | Page 8 of 12 240 00164-020 1ms/DIV 00164-017 2 ADR293 TERMINOLOGY Line Regulation The change in output voltage due to a specified change in input voltage. It includes the effects of self-heating. Line regulation is expressed in percent per volt, parts per million per volt, or microvolts per volt change in input voltage. Load Regulation The change in output voltage due to a specified change in load current. It includes the effects of self-heating. Load regulation is expressed in microvolts per milliampere, parts per million per milliampere, or ohms of dc output resistance. Long-Term Stability Typical shift of output voltage of 25C on a sample of parts subjected to high temperature operating life test of 1000 hours at 125C. VOUT = VOUT (t 0 ) - VOUT (t 1 ) VOUT [ppm ] = VOUT (t 0 ) - VOUT (t 1 ) VOUT (t 0 ) Temperature Coefficient The change of output voltage over the operating temperature change and normalized by the output voltage at 25C, expressed in ppm/C. TCVOUT [ppm/ C ] = VOUT ( 2 ) - VOUT (T1 ) VOUT ( 25C ) x (T2 ) - T1 x 10 6 where: VOUT (25C) = VOUT at 25C. VOUT (T1) = VOUT at Temperature 1. VOUT (T2) = VOUT at Temperature 2. Thermal Hysteresis Thermal hysteresis is defined as the change of output voltage after the device is cycled through temperatures from +25C to -40C to +85C and back to +25C. This is a typical value from a sample of parts put through such a cycle. VOUT - HYS = VOUT ( 25C ) - VOUT -TC x 10 6 VOUT - HYS [ppm ] = where: VOUT (t0) = VOUT at 25C at time 0. VOUT (t1) = VOUT at 25C after 1000 hours operation at 125C. NC = No Connect There are in fact connections at NC pins, which are reserved for manufacturing purposes. Users should not connect anything at NC pins. VOUT ( 25C ) - VOUT -TC VOUT ( 25C ) x 10 6 where: VOUT (25C) = VOUT at 25C. VOUT-TC = VOUT (25C) after temperature cycle at +25C to -40C to +85C and back to +25C. Rev. D | Page 9 of 12 ADR293 THEORY OF OPERATION The core of the XFET reference consists of two junction field effect transistors, one of which has an extra channel implant to raise its pinch-off voltage. By running the two JFETs at the same drain current, the difference in pinch-off voltage can be amplified and used to form a highly stable voltage reference. The intrinsic reference voltage is around 0.5 V with a negative temperature coefficient of about -120 ppm/K. This slope is essentially locked to the dielectric constant of silicon and can be closely compensated by adding a correction term generated in the same fashion as the proportional-to-temperature (PTAT) term used to compensate band gap references. The big advantage over a band gap reference is that the intrinsic temperature coefficient is some 30 times lower (therefore, less correction is needed) and this results in much lower noise, because most of the noise of a band gap reference comes from the temperature compensation circuitry. The simplified schematic in Figure 21 shows the basic topology of the ADR293. The temperature correction term is provided by a current source with value designed to be proportional to absolute temperature. The general equation is DEVICE POWER DISSIPATION CONSIDERATIONS The ADR293 is guaranteed to deliver load currents to 5 mA with an input voltage that ranges from 5.5 V to 15 V. When this device is used in applications with large input voltages, care should be exercised to avoid exceeding the published specifications for maximum power dissipation or junction temperature that could result in premature device failure. The following formula should be used to calculate a device's maximum junction temperature or dissipation: PD = TJ - TA JA where: TJ and TA are the junction temperature and ambient temperature, respectively. PD is the device power dissipation. JA is the device package thermal resistance. BASIC VOLTAGE REFERENCE CONNECTIONS References, in general, require a bypass capacitor connected from the VOUT pin to the GND pin. The circuit in Figure 22 illustrates the basic configuration for the ADR293. Note that the decoupling capacitors are not required for circuit stability. NC 1 R1 + R2 + R3 VOUT = VP + (I PTAT ) ( R3 ) R1 2 where: VP is the difference in pinch-off voltage between the two FETs. IPTAT is the positive temperature coefficient correction current. The process used for the XFET reference also features vertical NPN and PNP transistors, the latter of which are used as output devices to provide a very low dropout voltage. VIN I1 I1 1 VOUT VP IPTAT VOUT = GND R1 + R2 + R3 x VP + IPTAT x R3 R1 Figure 21. Simplified Schematic 00164-021 R3 1 EXTRA CHANNEL IMPLANT 10F 0.1F NC 7 NC NC 3 6 4 5 VOUT 0.1F NC NC = NO CONNECT Figure 22. Basic Voltage Reference Configuration NOISE PERFORMANCE The noise generated by the ADR293 is typically less than 15 V p-p over the 0.1 Hz to 10 Hz band. 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 Hz. TURN-ON TIME R1 R2 + ADR293 8 00164-022 The ADR293 uses a new reference generation technique known as XFET, which yields a reference with low noise, low supply current, and very low thermal hysteresis. 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 15 shows the typical turn-on time for the ADR293. Rev. D | Page 10 of 12 ADR293 APPLICATIONS KELVIN CONNECTIONS In many portable instrumentation applications where PC board cost and area go hand-in-hand, circuit interconnects are very often of dimensionally minimum width. These narrow lines can cause large voltage drops if the voltage reference is required to provide load currents to various functions. In fact, a circuit's interconnects can exhibit a typical line resistance of 0.45 m/square (1 oz. Cu, for example). Force and sense connections, also referred to as Kelvin connections, offer a convenient method of eliminating the effects of voltage drops in circuit wires. Load currents flowing through wiring resistance produce an error (VERROR = R x IL) at the load. However, the Kelvin connection in Figure 23 overcomes the problem by including the wiring resistance within the forcing loop of the op amp. Because the op amp senses the load voltage, op amp loop control forces the output to compensate for the wiring error and to produce the correct voltage at the load. 2 +VOUT SENSE VIN The ADR293 is ideal for providing a stable, low cost, and low power reference voltage in portable equipment power supplies. Figure 24 shows how the ADR293 can be used in a voltage regulator that not only has low output noise (as compared to switch mode design) and low power, but also a very fast recovery after current surges. Some precautions should be taken in the selection of the output capacitors. Too high an ESR (effective series resistance) could endanger the stability of the circuit. A solid tantalum capacitor, 16 V or higher, and an aluminum electrolytic capacitor, 10 V or higher, are recommended for C1 and C2, respectively. In addition, the path from the ground side of C1 and C2 to the ground side of R1 should be kept as short as possible. CHARGER INPUT 0.1F R3 510k 2 VIN ADR293 A1 VOUT 6 RLW ADR293 +VOUT FORCE 6V RL 1F LEAD-ACID BATTERY 100k VOUT 6 2 7 OP20 GND 3 6 IRF9530 4 4 GND 5V, 100mA 00164-025 4 + R1 402k 1% Figure 23. Advantage of Kelvin Connection R2 402k 1% C1 68F TANT + + C2 1000F ELECT Figure 24. Voltage Regulator for Portable Equipment Rev. D | Page 11 of 12 00164-026 RLW VIN VOLTAGE REGULATOR FOR PORTABLE EQUIPMENT ADR293 OUTLINE DIMENSIONS 5.00 (0.1968) 4.80 (0.1890) 5 1 6.20 (0.2441) 5.80 (0.2284) 4 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) 0.51 (0.0201) 0.31 (0.0122) COPLANARITY 0.10 SEATING PLANE 0.50 (0.0196) 0.25 (0.0099) 1.75 (0.0688) 1.35 (0.0532) 45 8 0 0.25 (0.0098) 0.17 (0.0067) 1.27 (0.0500) 0.40 (0.0157) 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. 012407-A 8 4.00 (0.1574) 3.80 (0.1497) Figure 25. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches) 3.10 3.00 2.90 8 5 4.50 4.40 4.30 1 6.40 BSC 4 PIN 1 0.65 BSC 0.15 0.05 1.20 MAX COPLANARITY 0.10 0.30 0.19 SEATING 0.20 PLANE 0.09 8 0 0.75 0.60 0.45 COMPLIANT TO JEDEC STANDARDS MO-153-AA Figure 26. 8-Lead Thin Shrink Small Outline Package [TSSOP] (RU-8) Dimensions shown in millimeters ORDERING GUIDE Model 1 ADR293ERZ ADR293ERZ-REEL ADR293GRZ ADR293GRZ-REEL7 ADR293GRUZ ADR293GRUZ-REEL ADR293GRUZ-REEL7 1 Output Voltage (V) 5.00 5.00 5.00 5.00 5.00 5.00 5.00 Initial Accuracy (%) 0.06 0.06 0.20 0.20 0.20 0.20 0.20 Temperature Coefficient (ppm/C max) 8 8 25 25 25 25 25 Temperature Range -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C Z = RoHS Compliant Part. (c)2001-2011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D00164-0-5/11(D) Rev. D | Page 12 of 12 Package Description 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead TSSOP 8-Lead TSSOP 8-Lead TSSOP Package Option R-8 R-8 R-8 R-8 RU-8 RU-8 RU-8 Ordering Quantity 98 2,500 98 1,000 96 2,500 1,000