Two-Terminal IC Temperature Transducer AD590 FLATPACK TO-52 FEATURES – Linear current output: 1 µA/K Wide temperature range: −55°C to +150°C Probe compatible ceramic sensor package 2-terminal device: voltage in/current out Laser trimmed to ±0.5°C calibration accuracy (AD590M) Excellent linearity: ±0.3°C over full range (AD590M) Wide power supply range: 4 V to 30 V Sensor isolation from case Low cost SOIC-8 NC 1 8 NC 7 NC TOP VIEW V– 3 (Not to Scale) 6 NC V+ 2 + NC 4 5 NC + 00533-C-001 NC = NO CONNECT – Figure 1. Pin Designations GENERAL DESCRIPTION The AD590 is a 2-terminal integrated circuit temperature transducer that produces an output current proportional to absolute temperature. For supply voltages between 4 V and 30 V the device acts as a high-impedance, constant current regulator passing 1 µA/K. Laser trimming of the chip’s thin-film resistors is used to calibrate the device to 298.2 µA output at 298.2 K (25°C). receiving circuitry. The output characteristics also make the AD590 easy to multiplex: the current can be switched by a CMOS multiplexer or the supply voltage can be switched by a logic gate output. PRODUCT HIGHLIGHTS 1. The AD590 should be used in any temperature-sensing application below 150°C in which conventional electrical temperature sensors are currently employed. The inherent low cost of a monolithic integrated circuit combined with the elimination of support circuitry makes the AD590 an attractive alternative for many temperature measurement situations. Linearization circuitry, precision voltage amplifiers, resistance measuring circuitry, and cold junction compensation are not needed in applying the AD590. The AD590 is a calibrated, 2-terminal temperature sensor requiring only a dc voltage supply (4 V to 30 V). Costly transmitters, filters, lead wire compensation, and linearization circuits are all unnecessary in applying the device. 2. State-of-the-art laser trimming at the wafer level in conjunction with extensive final testing ensures that AD590 units are easily interchangeable. 3. In addition to temperature measurement, applications include temperature compensation or correction of discrete components, biasing proportional to absolute temperature, flow rate measurement, level detection of fluids and anemometry. The AD590 is available in chip form, making it suitable for hybrid circuits and fast temperature measurements in protected environments. Superior interface rejection occurs, because the output is a current rather than a voltage. In addition, power requirements are low (1.5 mWs @ 5 V @ 25°C). These features make the AD590 easy to apply as a remote sensor. 4. The high output impedance (>10 MΩ) provides excellent rejection of supply voltage drift and ripple. For instance, changing the power supply from 5 V to 10 V results in only a 1 µA maximum current change, or 1°C equivalent error. 5. The AD590 is electrically durable: it withstands a forward voltage of up to 44 V and a reverse voltage of 20 V. Therefore, supply irregularities or pin reversal does not damage the device. The AD590 is particularly useful in remote sensing applications. The device is insensitive to voltage drops over long lines due to its high impedance current output. Any well-insulated twisted pair is sufficient for operation at hundreds of feet from the Rev. C 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: 781.326.8703 © 2003 Analog Devices, Inc. All rights reserved. AD590 TABLE OF CONTENTS Specifications..................................................................................... 3 AD590J and AD590K Specifications ......................................... 3 AD590L and AD590M Specifications........................................ 4 Absolute Maximum Ratings............................................................ 5 ESD Caution.................................................................................. 5 Product Description......................................................................... 6 Circuit Description....................................................................... 6 Explanation of Temperature Sensor Specifications ................. 6 Error Versus Temperature: with Calibration Error Trimmed Out...................................................................................................7 Error Versus Temperature: No User Trims ................................7 Nonlinearity ...................................................................................7 Voltage and Thermal Environment Effects ...............................8 General Applications...................................................................... 10 Outline Dimensions ....................................................................... 13 Ordering Guide .......................................................................... 14 Calibration Error .......................................................................... 7 REVISION HISTORY Revision C 9/03—Data Sheet Changed from REV. B to REV. C. Added SOIC-8 package…………………………Universal Change to Figure 1…………………………………….…1 Updated OUTLINE DIMENSIONS…………...……….13 Added ORDERING GUIDE………………...………….14 Rev. C | Page 2 of 16 AD590 SPECIFICATIONS AD590J AND AD590K SPECIFICATIONS Table 1. @ 25°C and VS = 5 V unless otherwise noted Parameter POWER SUPPLY Operating Voltage Range OUTPUT Nominal Current Output @ 25°C (298.2K) Nominal Temperature Coefficient Calibration Error @ 25°C Absolute Error (over rated performance temperature range) Without External Calibration Adjustment With 25°C Calibration Error Set to Zero Nonlinearity For TO-52 and Flatpack packages For 8-Lead SOIC package Repeatability1 Long-Term Drift2 Current Noise Power Supply Rejection 4 V ≤ VS ≤ 5 V 5 V ≤ VS ≤ 15 V 15 V ≤ VS ≤ 30 V Case Isolation to Either Lead Effective Shunt Capacitance Electrical Turn-On Time Reverse Bias Leakage Current3 (Reverse Voltage = 10 V) Min AD590J Typ 4 1 Max Min 30 4 AD590K Typ Max Unit 30 Volts ±5.0 ±2.5 µA µA/K °C ±10 ±3.0 ±5.5 ±2.0 °C °C ±1.5 ±1.5 ±0.1 ±0.1 ±0.8 ±1.0 ±0.1 ±0.1 298.2 1 298.2 1 40 40 °C °C °C °C pA/√Hz 0.5 0.2 0.1 1010 100 20 0.5 0.2 0.1 1010 100 20 µA/V µV/V µA/V Ω pF µs 10 10 pA Maximum deviation between +25°C readings after temperature cycling between –55°C and +150°C; guaranteed, not tested. Conditions: constant 5 V, constant 125°C; guaranteed, not tested. 3 Leakage current doubles every 10°C. Specifications shown in boldface are tested on all production units at final electrical test. Results from those tests are used to calculate outgoing quality levels. All min and max specifications are guaranteed, although only those shown in boldface are tested on all production units. 2 Rev. C | Page 3 of 16 AD590 AD590L AND AD590M SPECIFICATIONS Table 2. @ 25°C and VS = 5 V unless otherwise noted Parameter POWER SUPPLY Operating Voltage Range OUTPUT Nominal Current Output @ 25°C (298.2K) Nominal Temperature Coefficient Calibration Error @ +25°C Absolute Error (over rated performance temperature range) Without External Calibration Adjustment With ± 25°C Calibration Error Set to Zero Nonlinearity Repeatability1 Long-Term Drift2 Current Noise Power Supply Rejection 4 V ≤ VS ≤ 5 V 5 V ≤ VS ≤ 15 V 15 V ≤ VS ≤ 30 V Case Isolation to Either Lead Effective Shunt Capacitance Electrical Turn-On Time Reverse Bias Leakage Current3 (Reverse Voltage = 10 V) Min AD590L Typ Max Min 30 4 AD590M Typ Max 30 4 298.2 1 298.2 1 Unit Volts 40 40 µA µA/K °C °C °C °C °C °C °C pA/√Hz 0.5 0.2 0.1 1010 100 20 0.5 0.2 0.1 1010 100 20 µA/V µA/V µA/V Ω pF µs 10 10 pA ±1.0 ±0.5 ±3.0 ±1.6 ±0.4 ±0.1 ±0.1 ±1.7 ±1.0 ±0.3 ±0.1 ±0.1 1 Maximum deviation between +25°C readings after temperature cycling between –55°C and +150°C; guaranteed, not tested. Conditions: constant 5 V, constant 125°C; guaranteed, not tested. 3 Leakage current doubles every 10°C. Specifications shown in boldface are tested on all production units at final electrical test. Results from those tests are used to calculate outgoing quality levels. All min and max specifications are guaranteed, although only those shown in boldface are tested on all production units. °K +223° °C –50° +273° +298° +323° 0° °F –100° 0° +32° +25° +50° +100° +70° +373° +423° +100° +150° +200° +212° 5 o ( F − 32) K = oC + 273.15 9 9 o F = (oC + 32 ) oR = oF + 459.7 5 o C= Figure 2. Temperature Scale Conversion Equations Rev. C | Page 4 of 16 +300° 00533-C-002 2 AD590 ABSOLUTE MAXIMUM RATINGS Table 3. Parameter Forward Voltage ( E+ or E–) Reverse Voltage (E+ to E–) Breakdown Voltage (Case E+ or E–) Rated Performance Temperature Range1 Storage Temperature Range1 Lead Temperature (Soldering, 10 sec) Rating 44 V −20 V ±200 V −55°C to +150°C −65°C to +155°C 300°C Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only and 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. 1 The AD590 has been used at –100°C and +200°C for short periods of measurement with no physical damage to the device. However, the absolute errors specified apply to only the rated performance temperature range. 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. C | Page 5 of 16 AD590 PRODUCT DESCRIPTION The AD590H has 60 µ inches of gold plating on its Kovar leads and Kovar header. A resistance welder is used to seal the nickel cap to the header. The AD590 chip is eutectically mounted to the header and ultrasonically bonded to with 1 mil aluminum wire. Kovar composition: 53% iron nominal; 29% ±1% nickel; 17% ±1% cobalt; 0.65% manganese max; 0.20% silicon max; 0.10% aluminum max; 0.10% magnesium max; 0.10% zirconium max; 0.10% titanium max; 0.06% carbon max. PTAT current. Figure 4 is the schematic diagram of the AD590. In this figure, Q8 and Q11 are the transistors that produce the PTAT voltage. R5 and R6 convert the voltage to current. Q10, whose collector current tracks the collector currents in Q9 and Q11, supplies all the bias and substrate leakage current for the rest of the circuit, forcing the total current to be PTAT. R5 and R6 are laser-trimmed on the wafer to calibrate the device at 25°C. The AD590F is a ceramic package with gold plating on its Kovar leads, Kovar lid, and chip cavity. Solder of 80/20 Au/Sn composition is used for the 1.5 mil thick solder ring under the lid. The chip cavity has a nickel underlay between the metallization and the gold plating. The AD590 chip is eutectically mounted in the chip cavity at 410°C and ultrasonically bonded to with 1 mil aluminum wire. Note that the chip is in direct contact with the ceramic base, not the metal lid. When using the AD590 in die form, the chip substrate must be kept electrically isolated (floating) for correct circuit operation. Figure 5 shows the typical V–I characteristic of the circuit at 25°C and the temperature extremes. + Q2 R2 1040Ω Q5 Q3 Q6 Q12 Q7 CHIP SUBSTRATE 66MILS Q9 V+ 8 Q4 C1 26pF Q8 R3 5kΩ R4 11kΩ Q10 Q11 R5 1 146Ω R6 820Ω 1 00533-C-004 Q1 R1 260Ω – 42MILS Figure 4. Schematic Diagram V– IOUT (µA) 00533-C-003 THE AD590 IS AVAILABLE IN LASER-TRIMMED CHIP FORM; CONSULT THE CHIP CATALOG FOR DETAILS Figure 3. Metalization Diagram CIRCUIT DESCRIPTION 1 1 For a more detailed description, see M.P. Timko, “A Two-Terminal IC Temperature Transducer,” IEEE J. Solid State Circuits, Vol. SC-11, p. 784-788, Dec. 1976. Understanding the Specifications–AD590. +25°C 298 –55°C 218 00533-C-005 The AD590 uses a fundamental property of the silicon transistors from which it is made to realize its temperature proportional characteristic: if two identical transistors are operated at a constant ratio of collector current densities, r, then the difference in their base-emitter voltage will be (kT/q)(In r). Since both k (Boltzman’s constant) and q (the charge of an electron) are constant, the resulting voltage is directly proportional to absolute temperature (PTAT). In the AD590, this PTAT voltage is converted to a PTAT current by low temperature coefficient thin-film resistors. The total current of the device is then forced to be a multiple of this +150°C 423 0 1 2 3 4 5 SUPPLY VOLTAGE (V) 6 30 Figure 5. V-1 Plot EXPLANATION OF TEMPERATURE SENSOR SPECIFICATIONS The way in which the AD590 is specified makes it easy to apply in a wide variety of applications. It is important to understand the meaning of the various specifications and the effects of supply voltage and thermal environment on accuracy. Rev. C | Page 6 of 16 AD590 CALIBRATION ERROR At final factory test, the difference between the indicated temperature and the actual temperature is called the calibration error. Since this is a scale factory error, its contribution to the total error of the device is PTAT. For example, the effect of the 1°C specified maximum error of the AD590L varies from 0.73°C at –55°C to 1.42°C at 150°C. Figure 6 shows how an exaggerated calibration error would vary from the ideal over temperature. 5V + AD590 – R 100Ω – – ERROR VERSUS TEMPERATURE: WITH CALIBRATION ERROR TRIMMED OUT Each AD590 is tested for error over the temperature range with the calibration error trimmed out. This specification could also be called the “variance from PTAT,” because it is the maximum difference between the actual current over temperature and a PTAT multiplication of the actual current at 25°C. This error consists of a slope error and some curvature, mostly at the temperature extremes. Figure 8 shows a typical AD590K temperature curve before and after calibration error trimming. 2 BEFORE CALIBRATION TRIM CALIBRATION ERROR 0 AFTER CALIBRATION TRIM –2 00533-C-008 ABSOLUTE ERROR (°C) IDEAL TRANSFER FUNCTION 298.2 TEMPERATURE (°K) –55 150 TEMPERATURE (°C) Figure 8. Effect to Scale Factor Trim on Accuracy Figure 6. Calibration Error vs. Temperature The calibration error is a primary contributor to maximum total error in all AD590 grades. However, since it is a scale factor error, it is particularly easy to trim. Figure 7 shows the most elementary way of accomplishing this. To trim this circuit, the temperature of the AD590 is measured by a reference temperature sensor and R is trimmed so that VT = 1 mV/K at that temperature. Note that when this error is trimmed out at one temperature, its effect is zero over the entire temperature range. In most applications there is a current-to-voltage conversion resistor (or, as with a current input ADC, a reference) that can be trimmed for scale factor adjustment. 1 VT = 1mV/K Figure 7. One Temperature Trim 00533-C-006 IOUT (µA) CALIBRATION ERROR 298.2 + 950Ω ACTUAL TRANSFER FUNCTION IACTUAL + 00533-C-007 The AD590 is basically a PTAT (proportional to absolute temperature)1 current regulator. That is, the output current is equal to a scale factor times the temperature of the sensor in degrees Kelvin. This scale factor is trimmed to 1 µA/K at the factory, by adjusting the indicated temperature (that is, the output current) to agree with the actual temperature. This is done with 5 V across the device at a temperature within a few degrees of 25°C (298.2K). The device is then packaged and tested for accuracy over temperature. ERROR VERSUS TEMPERATURE: NO USER TRIMS Using the AD590 by simply measuring the current, the total error is the variance from PTAT, described above, plus the effect of the calibration error over temperature. For example, the AD590L maximum total error varies from 2.33°C at –55°C to 3.02°C at 150°C. For simplicity, only the large figure is shown on the specification page. NONLINEARITY Nonlinearity as it applies to the AD590 is the maximum deviation of current over temperature from a best-fit straight line. The nonlinearity of the AD590 over the −55°C to +150°C range is superior to all conventional electrical temperature sensors such as thermocouples, RTDs, and thermistors. Figure 9 shows the nonlinearity of the typical AD590K from Figure 8. T(°C) = T(K) –273.2. Zero on the Kelvin scale is “absolute zero”; there is no lower temperature. Rev. C | Page 7 of 16 AD590 VOLTAGE AND THERMAL ENVIRONMENT EFFECTS The power supply rejection specifications show the maximum expected change in output current versus input voltage changes. The insensitivity of the output to input voltage allows the use of unregulated supplies. It also means that hundreds of ohms of resistance (such as a CMOS multiplexer) can be tolerated in series with the device. 0.8 0.8°C MAX 0 0.8°C MAX 0.8°C MAX It is important to note that using a supply voltage other than 5 V does not change the PTAT nature of the AD590. In other words, this change is equivalent to a calibration error and can be removed by the scale factor trim (see Figure 8). 00533-C-009 –0.8 –1.6 –55 150 TEMPERATURE (°C) Figure 9. Nonlinearity Figure 10 shows a circuit in which the nonlinearity is the major contributor to error over temperature. The circuit is trimmed by adjusting R1 for a 0 V output with the AD590 at 0°C. R2 is then adjusted for 10 V out with the sensor at 100°C. Other pairs of temperatures may be used with this procedure as long as they are measured accurately by a reference sensor. Note that for 15 V output (150°C) the V+ of the op amp must be greater than 17 V. Also note that V− should be at least −4 V; if V− is ground, there is no voltage applied across the device. The AD590 specifications are guaranteed for use in a low thermal resistance environment with 5 V across the sensor. Large changes in the thermal resistance of the sensor’s environment change the amount of self-heating and result in changes in the output, which are predictable but not necessarily desirable. The thermal environment in which the AD590 is used determines two important characteristics: the effect of selfheating and the response of the sensor with time. Figure 12 is a model of the AD590 that demonstrates these characteristics. TJ θJC θCA TC 15V 35.7kΩ AD581 R1 2kΩ 97.6kΩ + R2 5kΩ P 30pF CC – TA Figure 12. Thermal Circuit Model 27kΩ As an example, for the TO-52 package, θJC is the thermal resistance between the chip and the case, about 26°C/W. θCA is the thermal resistance between the case and the surroundings and is determined by the characteristics of the thermal connection. Power source P represents the power dissipated on the chip. The rise of the junction temperature, TJ, above the ambient temperature TA is 100mV/°C VT = 100mV/°C 00533-C-010 AD707A AD590 V– Figure 10. 2-Temperature Trim TJ − TA = P (θ JC + θ CA ) 2 Equation 1. 0 –2 00533-C-011 TEMPERATURE (°C) CCH 00533-C-012 ABSOLUTE ERROR (°C) 1.6 –55 0 100 TEMPERATURE (°C) Figure 11. Typical 2-Trim Accuracy 150 Table 4 gives the sum of θJC and θCA for several common thermal media for both the H and F packages. The heat sink used was a common clip-on. Using Equation 1, the temperature rise of an AD590 H package in a stirred bath at 25°C, when driven with a 5 V supply, is 0.06°C. However, for the same conditions in still air, the temperature rise is 0.72°C. For a given supply voltage, the temperature rise varies with the current and is PTAT. Therefore, if an application circuit is trimmed with the sensor in the same thermal environment in which it will be used, the scale factor trim compensates for this effect over the entire temperature range. Rev. C | Page 8 of 16 AD590 response, T (t). Table 4 shows the effective time constant, τ, for several media. Table 4. Thermal Resistance θJC + θCA (°C/Watt) H F 30 10 42 60 H 0.6 1.4 τ (sec) F 0.1 0.6 45 115 – 190 5.0 13.5 – 10.0 191 480 – 650 108 60 – 30 TFINAL SENSED TEMPERATURE Medium Aluminum Block Stirred Oil2 Moving Air3 With Heat Sink Without Heat Sink Still Air With Heat Sink Without Heat Sink 1 T(t) = TINITIAL + (TFINAL – TINITIAL) × (1 – e–t/τ) τ is dependent upon velocity of oil; average of several velocities listed above. Air velocity @ 9 ft/sec. 3 The time constant is defined as the time required to reach 63.2% of an instantaneous temperature change. 00533-C-013 1 2 TINITIAL The time response of the AD590 to a step change in temperature is determined by the thermal resistances and the thermal capacities of the chip, CCH, and the case, CC. CCH is about 0.04 Ws/°C for the AD590. CC varies with the measured medium, because it includes anything that is in direct thermal contact with the case. The single time constant exponential curve of Figure 13 is usually sufficient to describe the time Rev. C | Page 9 of 16 τ 4τ TIME Figure 13. Time Response Curve AD590 GENERAL APPLICATIONS V+ Figure 14 demonstrates the use of a low cost digital panel meter for the display of temperature on either the Kelvin, Celsius, or Fahrenheit scales. For Kelvin temperature, Pins 9, 4, and 2 are grounded; for Fahrenheit temperature, Pins 4 and 2 are left open. R3 10kΩ + AD590L #2 – – + 8 9 OFFSET CALIBRATION AD2040 4 GAIN SCALING 2 OFFSET SCALING 6 AD590 – 5 3 GND R2 50kΩ (T1 – T2) × (10mV/°C) + R4 10kΩ V– Figure 16. Differential Measurements 00533-C-014 + AD707A R1 5MΩ 00533-C-016 AD590L #1 – 5V Figure 14. Variable Scale Display The above configuration yields a 3-digit display with 1°C or 1°F resolution, in addition to an absolute accuracy of ±2.0°C over the −55°C to +125°C temperature range, if a one-temperature calibration is performed on an AD590K, AD590L, or AD590M. Connecting several AD590 units in series as shown in Figure 15 allows the minimum of all the sensed temperatures to be indicated. In contrast, using the sensors in parallel yields the average of the sensed temperatures. Figure 17 is an example of a cold junction compensation circuit for a Type J thermocouple using the AD590 to monitor the reference junction temperature. This circuit replaces an ice-bath as the thermocouple reference for ambient temperatures between 15°C and 35°C. The circuit is calibrated by adjusting RT for a proper meter reading with the measuring junction at a known reference temperature and the circuit near 25°C. Using components with the TCs as specified in Figure 17, compensation accuracy is within ±0.5°C for circuit temperatures between 15°C and 35°C. Other thermocouple types can be accommodated with different resistor values. Note that the TCs of the voltage reference and the resistors are the primary contributors to error. 7.5V 15V + 5V + AD590 + + + – + – – – – AD590 + – 333.3Ω (0.1%) + VT AVG – + AD580 00533-C-015 10kΩ (0.1%) + VT MIN CONSTANTAN AD590 AD590 – IRON REFERENCE JUNCTION 52.3Ω VOUT – 8.66kΩ RT 1kΩ Figure 15. Series and Parallel Connection The circuit in Figure 16 demonstrates one method by which differential temperature measurements can be made. R1 and R2 can be used to trim the output of the op amp to indicate a desired temperature difference. For example, the inherent offset between the two devices can be trimmed in. If V+ and V− are radically different, then the difference in internal dissipation causes a differential internal temperature rise. This effect can be used to measure the ambient thermal resistance seen by the sensors in applications such as fluid-level detectors or anemometry. – CU + – MEASURING JUNCTION METER RESISTORS ARE 1%, 50PPM/°C 00533-C-017 AD590 – + Figure 17. Cold Junction Compensation Circuit for Type J Thermocouple Figure 18 is an example of a current transmitter designed to be used with 40 V, 1 kΩ systems; it uses its full current range of 4 mA to 20 mA for a narrow span of measured temperatures. In this example, the 1 µA/K output of the AD590 is amplified to 1 mA/°C and offset so that 4 mA is equivalent to 17°C and 20 mA is equivalent to 33°C. RT is trimmed for proper reading at an intermediate reference temperature. With a suitable choice of resistors, any temperature range within the operating limits of the AD590 may be chosen. Rev. C | Page 10 of 16 AD590 V+ + AD581 – VOUT 1.25kΩ 35.7kΩ AD707A – + 12.7kΩ 10kΩ 500Ω 10Ω 00533-C-018 0.01µF 5kΩ V– BIT 2 BIT 7 200Ω, 15T +5V BIT 3 BIT 6 +2.5V BIT 4 BIT 5 + V+ V+ 10V V– RH AD590 + – RSET RB HEATING ELEMENTS 7 2 – AD590 – C1 AD580 200Ω +5V 1kΩ 3 8 LM311 2 1 4 7 OUTPUT HIGHTEMPERATURE ABOVE SET POINT OUTPUT LOWTEMPERATURE BELOW SET POINT 5.1MΩ –15V 6.8kΩ Figure 20. DAC Set Point The voltage compliance and the reverse blocking characteristic of the AD590 allows it to be powered directly from 5 V CMOS logic. This permits easy multiplexing, switching, or pulsing for minimum internal heat dissipation. In Figure 21, any AD590 connected to a logic high passes a signal current through the current measuring circuitry, while those connected to a logic zero pass insignificant current. The outputs used to drive the AD590s may be employed for other purposes, but the additional capacitance due to the AD590 should be taken into account. 5V 1 4 10kΩ GND 00533-C-019 3 + +5V –15V LM311 RL 1.15kΩ BIT 8 1kΩ, 15T Figure 19 is an example of a variable temperature control circuit (thermostat) using the AD590. RH and RL are selected to set the high and low limits for RSET. RSET could be a simple pot, a calibrated multiturn pot, or a switched resistive divider. Powering the AD590 from the 10 V reference isolates the AD590 from supply variations while maintaining a reasonable voltage (~7 V) across it. Capacitor C1 is often needed to filter extraneous noise from remote sensors. RB is determined by the β of the power transistor and the current requirements of the load. +5V BIT 1 6.98kΩ Figure 18. 4 mA to 20 mA Current Transmitter AD581 OUT MC 1408/1508 DAC OUT – 00533-C-020 30pF RT 5kΩ + AD590 REF –15V + CMOS GATES Figure 19. Simple Temperature Control Circuit + + Figure 20 shows that the AD590 can be configured with an 8-bit DAC to produce a digitally controlled set point. This particular circuit operates from 0°C (all inputs high) to 51.0°C (all inputs low) in 0.2°C steps. The comparator is shown with 1.0°C hysteresis, which is usually necessary to guard-band for extraneous noise. Omitting the 5.1 MΩ resistor results in no hysteresis. + – AD590 – – – 1kΩ (0.1%) 00533-C-021 4mA = 17°C 12mA = 25°C 20mA = 33°C 20pF Figure 21. AD590 Driven from CMOS Logic CMOS analog multiplexers can also be used to switch AD590 current. Due to the AD590’s current mode, the resistance of such switches is unimportant as long as 4 V is maintained across the transducer. Figure 22 shows a circuit that combines the principle demonstrated in Figure 21 with an 8-channel CMOS multiplexer. The resulting circuit can select 1–80 sensors over only 18 wires with a 7-bit binary word. Rev. C | Page 11 of 16 AD590 The inhibit input on the multiplexer turns all sensors off for minimum dissipation while idling. up to eight channels of ±0.5°C absolute accuracy over the temperature range of −55°C to +125°C. The high temperature restriction of 125°C is due to the output range of the op amps; output to 150°C can be achieved by using a 20 V supply for the op amp. Figure 23 demonstrates a method of multiplexing the AD590 in the two-trim mode (see Figure 10 and Figure 11). Additional AD590s and their associated resistors can be added to multiplex 10V 16 4028 CMOS BCD-TODECIMAL 11 DECODER 12 13 10 8 ROW SELECT 0 1 2 3 14 2 + + + + – – 22 02 + – 12 16 9 10 11 6 INHIBIT + – 11 01 + 2 1 0 15 14 13 – 21 – 10V COLUMN SELECT + + – – 20 LOGIC LEVEL INTERFACE – 10 AD590 00 4051 CMOS ANALOG MULTIPLEXER BINARY TO 1-OF-8 DECODER 7 8 00533-C-022 10kΩ 10mV/°C Figure 22. Matrix Multiplexer +15V 35.7kΩ + 35.7kΩ – 5kΩ 2kΩ 5kΩ 97.6kΩ 97.6kΩ VOUT V+ S1 AD707A S2 DECODER/ DRIVER 27kΩ 10mV/°C –15V S8 +15V AD7501 –15V + AD590L – + – TTL/DTL TO CMOS INTERFACE EN AD590L BINARY CHANNEL SELECT –5V TO –15V Figure 23. 8-Channel Multiplexer Rev. C | Page 12 of 16 00533-C-023 AD581 2kΩ AD590 OUTLINE DIMENSIONS 0.230 (5.84) 0.209 (5.31) 0.195 (4.95) 0.178 (4.52) 0.150 (3.81) 0.115 (2.92) 0.050 (1.27) MAX 0.030 (0.76) MAX 0.019 (0.48) 0.016 (0.41) 0.050 (1.27) T.P. 0.093 (2.36) 0.081 (2.06) 0.055 (1.40) 0.050 (1.27) 0.045 (1.14) 0.250 (6.35) MIN 0.021 (0.53) MAX POSITIVE LEAD INDICATOR 0.019 (0.48) 0.017 (0.43) 0.015 (0.38) 0.500 (12.70) MIN 0.500 (12.69) MIN 3 0.100 (2.54) T.P. 2 0.050 (1.27) T.P. 0.230 (5.84) 0.250 (6.35) 0.0065 (0.17) 0.0050 (0.13) 0.0045 (0.12) 0.050 (1.27) 0.041 (1.04) 0.046 (1.17) 0.036 (0.91) 1 45 T.P. CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETERS DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN Figure 25. 3-Pin Metal Header Package [TO-52] (H-03) Dimensions shown in inches and (millimeters) Figure 24. 2-Lead Ceramic Flat Package [CQFP] (F-2) Dimensions shown in inches and (millimeters) 5.00 (0.1968) 4.80 (0.1890) 8 4.00 (0.1574) 3.80 (0.1497) 1 5 4 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) 0.048 (1.22) 0.028 (0.71) 6.20 (0.2440) 5.80 (0.2284) 1.75 (0.0688) 1.35 (0.0532) 0.51 (0.0201) COPLANARITY SEATING 0.31 (0.0122) 0.10 PLANE 0.50 (0.0196) × 45° 0.25 (0.0099) 8° 0.25 (0.0098) 0° 1.27 (0.0500) 0.40 (0.0157) 0.17 (0.0067) COMPLIANT TO JEDEC STANDARDS MS-012AA 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 26. 8-Lead Standard Small Outline Package [SOIC] Narrow Body (R-8) Dimensions shown in millimeters and (inches) Rev. C | Page 13 of 16 AD590 ORDERING GUIDE Model AD590JH1 AD590JF1 AD590JR AD590KH1 AD590KF1 AD590KR AD590LH1 AD590LF1 AD590MH1 AD590MF1 AD590JR-REEL AD590KR-REEL AD590JCHIPS Temperature Range −55°C to +150°C −55°C to +150°C −55°C to +150°C −55°C to +150°C −55°C to +150°C −55°C to +150°C −55°C to +150°C −55°C to +150°C −55°C to +150°C −55°C to +150°C −55°C to +150°C −55°C to +150°C −55°C to +150°C Package Description TO-52 Flatpack 8-Lead SOIC TO-52 Flatpack 8-Lead SOIC TO-52 Flatpack TO-52 Flatpack 8-Lead SOIC 8-Lead SOIC TO-52 1 Available in 883B; consult factory for data sheet. Rev. C | Page 14 of 16 Package Option H-03A F-2A SOIC-8 H-03A F-2A SOIC-8 H-03A F-2A H-03A F-2A SOIC-8 SOIC-8 H-03A AD590 NOTES Rev. C | Page 15 of 16 AD590 NOTES © 2003 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. C00533–0–9/03(C) Rev. C | Page 16 of 16