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| Two-Terminal IC Temperature Transducer AD590 FLATPACK TO-52 - NC 1 V+ 2 + NC 4 SOIC-8 8 FEATURES Linear current output: 1 A/K Wide temperature range: -55C to +150C Probe compatible ceramic sensor package 2-terminal device: voltage in/current out Laser trimmed to 0.5C calibration accuracy (AD590M) Excellent linearity: 0.3C over full range (AD590M) Wide power supply range: 4 V to 30 V Sensor isolation from case Low cost NC 7 NC TOP VIEW V- 3 (Not to Scale) 6 NC 5 NC 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 A/K. Laser trimming of the chip's thin-film resistors is used to calibrate the device to 298.2 A output at 298.2 K (25C). The AD590 should be used in any temperature-sensing application below 150C 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. 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. 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 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 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. State-of-the-art laser trimming at the wafer level in conjunction with extensive final testing ensures that AD590 units are easily interchangeable. 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 @ 25C). These features make the AD590 easy to apply as a remote sensor. The high output impedance (>10 M) 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 A maximum current change, or 1C equivalent error. 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. 2. 3. 4. 5. 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 (c) 2003 Analog Devices, Inc. All rights reserved. 00533-C-001 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 Calibration Error .......................................................................... 7 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 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. @ 25C and VS = 5 V unless otherwise noted Parameter POWER SUPPLY Operating Voltage Range OUTPUT Nominal Current Output @ 25C (298.2K) Nominal Temperature Coefficient Calibration Error @ 25C Absolute Error (over rated performance temperature range) Without External Calibration Adjustment With 25C 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 4 298.2 1 5.0 10 3.0 1.5 1.5 0.1 0.1 40 0.5 0.2 0.1 1010 100 20 10 40 0.5 0.2 0.1 1010 100 20 10 AD590J Typ Max 30 Min 4 298.2 1 2.5 5.5 2.0 0.8 1.0 0.1 0.1 AD590K Typ Max 30 Unit Volts A A/K C C C C C C C pA/Hz A/V V/V A/V pF s pA 1 2 Maximum deviation between +25C readings after temperature cycling between -55C and +150C; guaranteed, not tested. Conditions: constant 5 V, constant 125C; guaranteed, not tested. 3 Leakage current doubles every 10C. 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. Rev. C | Page 3 of 16 AD590 AD590L AND AD590M SPECIFICATIONS Table 2. @ 25C and VS = 5 V unless otherwise noted Parameter POWER SUPPLY Operating Voltage Range OUTPUT Nominal Current Output @ 25C (298.2K) Nominal Temperature Coefficient Calibration Error @ +25C Absolute Error (over rated performance temperature range) Without External Calibration Adjustment With 25C 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 4 298.2 1 1.0 3.0 1.6 0.4 0.1 0.1 40 0.5 0.2 0.1 1010 100 20 10 40 0.5 0.2 0.1 1010 100 20 10 AD590L Typ Max 30 Min 4 298.2 1 0.5 1.7 1.0 0.3 0.1 0.1 AD590M Typ Max 30 Unit Volts A A/K C C C C C C C pA/Hz A/V A/V A/V pF s pA 1 2 Maximum deviation between +25C readings after temperature cycling between -55C and +150C; guaranteed, not tested. Conditions: constant 5 V, constant 125C; guaranteed, not tested. 3 Leakage current doubles every 10C. 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 C +223 -50 +273 +298 +323 0 +25 +50 +373 +100 +423 +150 F -100 0 +32 +100 +70 +200 +212 +300 5o ( 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 00533-C-002 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) 1 Rating 44 V -20 V 200 V -55C to +150C -65C to +155C 300C 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. The AD590 has been used at -100C and +200C 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 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. 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 410C 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. 66MILS 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 25C. Figure 5 shows the typical V-I characteristic of the circuit at 25C and the temperature extremes. + R1 260 Q1 Q2 Q6 Q7 Q12 Q5 R2 1040 Q3 C1 26pF Q8 Q4 CHIP SUBSTRATE Q9 V+ R3 5k Q10 R4 11k Q11 1 00533-C-004 8 R6 820 - R5 1 146 42MILS Figure 4. Schematic Diagram V- IOUT (A) THE AD590 IS AVAILABLE IN LASER-TRIMMED CHIP FORM; CONSULT THE CHIP CATALOG FOR DETAILS 00533-C-003 423 +150C 298 +25C -55C Figure 3. Metalization Diagram CIRCUIT DESCRIPTION 1 218 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 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. 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. Rev. C | Page 6 of 16 00533-C-005 AD590 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 A/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 25C (298.2K). The device is then packaged and tested for accuracy over temperature. 5V + + AD590 - R 100 950 - - + Figure 7. One Temperature Trim 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 1C specified maximum error of the AD590L varies from 0.73C at -55C to 1.42C at 150C. Figure 6 shows how an exaggerated calibration error would vary from the ideal over temperature. 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 25C. 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. ABSOLUTE ERROR (C) ACTUAL TRANSFER FUNCTION 2 BEFORE CALIBRATION TRIM CALIBRATION ERROR 0 AFTER CALIBRATION TRIM 00533-C-008 IOUT (A) IACTUAL CALIBRATION ERROR 298.2 IDEAL TRANSFER FUNCTION 00533-C-006 -2 298.2 TEMPERATURE (K) -55 TEMPERATURE (C) 00533-C-007 VT = 1mV/K 150 Figure 6. Calibration Error vs. Temperature Figure 8. Effect to Scale Factor Trim on Accuracy 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. 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 2.33C at -55C to 3.02C at 150C. 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 -55C to +150C 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. 1 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 1.6 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. 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). 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 15V 35.7k R1 2k 97.6k R2 5k 30pF 27k AD707A AD590 V- ABSOLUTE ERROR (C) 0.8 0.8C MAX 0 0.8C MAX -0.8 00533-C-009 0.8C MAX -1.6 -55 TEMPERATURE (C) 150 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 0C. R2 is then adjusted for 10 V out with the sensor at 100C. 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 (150C) 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. JC TC CA + TA 00533-C-012 P CCH CC AD581 - Figure 12. Thermal Circuit Model 100mV/C VT = 100mV/C 00533-C-010 Figure 10. 2-Temperature Trim As an example, for the TO-52 package, JC is the thermal resistance between the chip and the case, about 26C/W. CA 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 TJ - TA = P ( JC + CA ) Equation 1. 2 TEMPERATURE (C) 0 -2 -55 0 TEMPERATURE (C) 100 150 Figure 11. Typical 2-Trim Accuracy Table 4 gives the sum of JC and CA 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 25C, when driven with a 5 V supply, is 0.06C. However, for the same conditions in still air, the temperature rise is 0.72C. 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. 00533-C-011 Rev. C | Page 8 of 16 AD590 Table 4. Thermal Resistance Medium Aluminum Block Stirred Oil2 Moving Air3 With Heat Sink Without Heat Sink Still Air With Heat Sink Without Heat Sink 1 2 JC + CA (C/Watt) H F 30 10 42 60 45 115 191 480 - 190 - 650 H 0.6 1.4 5.0 13.5 108 60 (sec) F 0.1 0.6 - 10.0 - 30 1 response, T (t). Table 4 shows the effective time constant, , for several media. TFINAL SENSED TEMPERATURE T(t) = TINITIAL + (TFINAL - TINITIAL) x (1 - e-t/) 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. 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 4 TIME Figure 13. Time Response Curve Rev. C | Page 9 of 16 00533-C-013 AD590 GENERAL APPLICATIONS 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. 5V 8 OFFSET CALIBRATION GAIN SCALING OFFSET SCALING 00533-C-014 V+ + R3 10k AD590L #2 - - + AD590L #1 - 9 4 2 R2 50k R1 5M R4 10k V- AD707A + (T1 - T2) x (10mV/C) 00533-C-016 + 6 AD590 - 5 AD2040 3 Figure 16. Differential Measurements GND Figure 14. Variable Scale Display The above configuration yields a 3-digit display with 1C or 1F resolution, in addition to an absolute accuracy of 2.0C over the -55C to +125C 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. 15V + 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 15C and 35C. 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 25C. Using components with the TCs as specified in Figure 17, compensation accuracy is within 0.5C for circuit temperatures between 15C and 35C. 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 AD590 - + 5V + REFERENCE JUNCTION IRON CONSTANTAN AD590 - + + - + - + AD590 - + + AD580 00533-C-015 AD590 - + VT AVG - 52.3 AD590 - 10k (0.1%) + VT MIN - 333.3 (0.1%) CU + METER - - MEASURING JUNCTION - VOUT 8.66k RT 1k 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. RESISTORS ARE 1%, 50PPM/C 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 k 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 A/K output of the AD590 is amplified to 1 mA/C and offset so that 4 mA is equivalent to 17C and 20 mA is equivalent to 33C. 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 00533-C-017 AD590 V+ + - 20pF 4mA = 17C 12mA = 25C 20mA = 33C AD581 VOUT 35.7k RT 5k 30pF - 1.25k -15V DAC OUT BIT 1 500 REF + AD590 MC 1408/1508 +5V 1.15k BIT 8 BIT 7 BIT 6 BIT 5 200, 15T +5V +2.5V - AD707A + 12.7k 5k BIT 2 BIT 3 BIT 4 00533-C-018 AD580 0.01F 10k 10 200 V- 6.98k 1k, 15T + 3 +5V +5V 1k Figure 18. 4 mA to 20 mA Current Transmitter 8 7 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 of the power transistor and the current requirements of the load. V+ V+ V- RH RSET RL C1 AD581 OUT 10V - AD590 LM311 2 1 4 -15V 6.8k OUTPUT HIGHTEMPERATURE ABOVE SET POINT OUTPUT LOWTEMPERATURE BELOW SET POINT 5.1M 00533-C-020 -15V Figure 20. DAC Set Point AD590 + - 2- 7 RB HEATING ELEMENTS 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 LM311 3+ 10k GND 1 4 00533-C-019 + CMOS GATES + + - - AD590 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 0C (all inputs high) to 51.0C (all inputs low) in 0.2C steps. The comparator is shown with 1.0C hysteresis, which is usually necessary to guard-band for extraneous noise. Omitting the 5.1 M resistor results in no hysteresis. + - - 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 00533-C-021 1k (0.1%) AD590 The inhibit input on the multiplexer turns all sensors off for minimum dissipation while idling. 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 up to eight channels of 0.5C absolute accuracy over the temperature range of -55C to +125C. The high temperature restriction of 125C is due to the output range of the op amps; output to 150C can be achieved by using a 20 V supply for the op amp. 10V 16 3 14 2 0 1 2 + + + - - 22 - 12 02 + - + - 21 - 11 01 + - + + - 20 - 10 + ROW SELECT 4028 CMOS BCD-TODECIMAL 11 DECODER 12 13 10 8 10V 16 9 10 11 6 AD590 00 2 15 1 14 0 13 COLUMN SELECT INHIBIT LOGIC LEVEL INTERFACE BINARY TO 1-OF-8 DECODER 7 8 4051 CMOS ANALOG MULTIPLEXER Figure 22. Matrix Multiplexer +15V + 35.7k 35.7k 2k 2k 5k 5k 97.6k 97.6k V+ AD581 - VOUT S1 S2 DECODER/ DRIVER S8 AD707A 10mV/C 27k -15V +15V -15V AD7501 TTL/DTL TO CMOS INTERFACE + + - EN AD590L - AD590L -5V TO -15V Figure 23. 8-Channel Multiplexer Rev. C | Page 12 of 16 00533-C-023 BINARY CHANNEL SELECT 00533-C-022 10k 10mV/C AD590 OUTLINE DIMENSIONS 0.230 (5.84) 0.209 (5.31) 0.195 (4.95) 0.178 (4.52) 0.030 (0.76) MAX 0.050 (1.27) MAX 0.150 (3.81) 0.115 (2.92) 0.019 (0.48) 0.016 (0.41) 0.021 (0.53) MAX 0.250 (6.35) MIN 0.500 (12.70) MIN 0.019 (0.48) 0.017 (0.43) 0.015 (0.38) POSITIVE LEAD INDICATOR 0.050 (1.27) T.P. 0.093 (2.36) 0.081 (2.06) 3 0.100 (2.54) T.P. 0.050 (1.27) T.P. 2 1 0.048 (1.22) 0.028 (0.71) 0.046 (1.17) 0.036 (0.91) 45 T.P. 0.055 (1.40) 0.050 (1.27) 0.045 (1.14) 0.500 (12.69) MIN 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) 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 24. 2-Lead Ceramic Flat Package [CQFP] (F-2) Dimensions shown in inches and (millimeters) Figure 25. 3-Pin Metal Header Package [TO-52] (H-03) Dimensions shown in inches and (millimeters) 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-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 1 Temperature Range -55C to +150C -55C to +150C -55C to +150C -55C to +150C -55C to +150C -55C to +150C -55C to +150C -55C to +150C -55C to +150C -55C to +150C -55C to +150C -55C to +150C -55C to +150C 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 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 Available in 883B; consult factory for data sheet. Rev. C | Page 14 of 16 AD590 NOTES Rev. C | Page 15 of 16 AD590 NOTES (c) 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 This datasheet has been download from: www..com Datasheets for electronics components. |
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