2-Terminal IC Temperature Transducer AD590 FEATURES PIN CONFIGURATIONS 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 NC 1 NC – 00533-024 + NC 4 5 NC NC = NO CONNECT 00533-001 7 NC TOP VIEW V– 3 (Not to Scale) 6 NC Figure 1. 2-Lead FLATPACK Figure 2. 8-Lead SOIC – 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). 00533-025 + Figure 3. 3-Pin TO-52 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. PRODUCT HIGHLIGHTS 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. 8 V+ 2 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. 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. Superior interface rejection occurs because the output is a current rather than a voltage. In addition, power requirements are low (1.5 mW @ 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. Rev. E 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 ©2006–2009 Analog Devices, Inc. All rights reserved. AD590 TABLE OF CONTENTS Features .............................................................................................. 1 Product Description ..........................................................................6 General Description ......................................................................... 1 Explanation of Temperature Sensor Specifications ..................7 Pin Configurations ........................................................................... 1 Calibration Error ...........................................................................7 Product Highlights ........................................................................... 1 Error vs. Temperature: Calibration Error Trimmed Out .........7 Revision History ............................................................................... 2 Error vs. Temperature: No User Trims .......................................7 Specifications..................................................................................... 3 Nonlinearity ...................................................................................7 AD590J and AD590K Specifications ......................................... 3 Voltage and Thermal Environment Effects ...............................8 AD590L and AD590M Specifications ....................................... 4 General Applications...................................................................... 10 Absolute Maximum Ratings............................................................ 5 Outline Dimensions ....................................................................... 13 ESD Caution .................................................................................. 5 Ordering Guide .......................................................................... 14 REVISION HISTORY 9/09—Rev. D to Rev. E Changes to Product Description Section ...................................... 6 Updated Outline Dimensions ....................................................... 13 Changes to Ordering Guide .......................................................... 14 1/06—Rev. C to Rev. D Updated Format .................................................................. Universal Changes to Figure 4 Equation ......................................................... 4 9/03—Rev. B to Rev. C Added SOIC-8 Package...................................................... Universal Change to Figure 1 ........................................................................... 1 Updated Outline Dimensions ....................................................... 13 Added Ordering Guide .................................................................. 14 Rev. E | Page 2 of 16 AD590 SPECIFICATIONS AD590J AND AD590K SPECIFICATIONS 25°C and VS = 5 V, unless otherwise noted.1 Table 1. 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 Repeatability2 Long-Term Drift3 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 Current (Reverse Voltage = 10 V)4 Min AD590J Typ Max 30 4 1 Min AD590K Typ Max Unit 30 V ±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 4 298.2 1 40 40 °C °C °C °C pA/√Hz 0.5 0.2 0.1 1010 100 20 10 0.5 0.2 0.1 1010 100 20 10 μA/V μV/V μA/V Ω pF μs pA 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 minimum and maximum specifications are guaranteed, although only those shown in boldface are tested on all production units. 2 Maximum deviation between +25°C readings after temperature cycling between −55°C and +150°C; guaranteed, not tested. 3 Conditions: constant 5 V, constant 125°C; guaranteed, not tested. 4 Leakage current doubles every 10°C. Rev. E | Page 3 of 16 AD590 AD590L AND AD590M SPECIFICATIONS 25°C and VS = 5 V, unless otherwise noted.1 Table 2. 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 Repeatability2 Long-Term Drift3 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 Current (Reverse Voltage = 10 V)4 Min AD590L Typ Max Min 30 4 AD590M Typ Max 30 4 298.2 1 298.2 1 Unit V 40 40 μA μA/K °C °C °C °C °C °C °C pA/√Hz 0.5 0.2 0.1 1010 100 20 10 0.5 0.2 0.1 1010 100 20 10 μA/V μA/V μA/V Ω pF μs 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 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 minimum and maximum specifications are guaranteed, although only those shown in boldface are tested on all production units. Maximum deviation between +25°C readings after temperature cycling between −55°C and +150°C; guaranteed, not tested. 3 Conditions: constant 5 V, constant 125°C; guaranteed, not tested. 4 Leakage current doubles every 10°C. °K +223° °C –50° °F –100° +273° +298° +323° 0° +25° 0° +32° o o C= +50° +100° +70° +373° +423° +100° +150° +200° +212° 5 o ( F − 32) K = oC + 273.15 9 9 F = ⎛⎜ oC + 32 ⎞⎟ oR = o F + 459.7 ⎝5 ⎠ Figure 4. Temperature Scale Conversion Equations Rev. E | Page 4 of 16 +300° 00533-002 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 Range 1 Storage Temperature Range1 Lead Temperature (Soldering, 10 sec) 1 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. The AD590 was 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. E | Page 5 of 16 AD590 PRODUCT DESCRIPTION The AD590 is a 2-terminal temperature-to-voltage transducer. It is available in a variety of accuracy grades and packages. When using the AD590 in die form, the chip substrate must be kept electrically isolated (floating) for correct circuit operation. Figure 7 shows the typical V–I characteristic of the circuit at 25°C and the temperature extremes. + 66MILS Q2 Q1 R1 260Ω R2 1040Ω Q5 Q3 V+ Q4 C1 26pF Q6 Q12 Q7 Q8 42MILS V– Q9 8 R4 11kΩ Q10 R5 146Ω R6 820Ω 00533-003 THE AD590 IS AVAILABLE IN LASER-TRIMMED CHIP FORM; CONSULT THE CHIP CATALOG FOR DETAILS R3 5kΩ Q11 1 1 00533-004 CHIP SUBSTRATE – Figure 6. Schematic Diagram Figure 5. Metallization Diagram 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 is (kT/q)(In r). Because both k (Boltzman’s constant) and q (the charge of an electron) are constant, the resulting voltage is directly proportional to absolute temperature (PTAT). 1 +150°C IOUT (µA) 423 –55°C 218 00533-005 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 PTAT current. Figure 6 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. +25°C 298 0 1 2 3 4 5 SUPPLY VOLTAGE (V) 6 30 Figure 7. V–I Plot 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. E | Page 6 of 16 AD590 5V + EXPLANATION OF TEMPERATURE SENSOR SPECIFICATIONS + AD590 The way in which the AD590 is specified makes it easy to apply it in a wide variety of applications. It is important to understand the meaning of the various specifications and the effects of the supply voltage and thermal environment on accuracy. R 100Ω + VT = 1mV/K 950Ω – – 00533-007 – Figure 9. One Temperature Trim 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 8 shows how an exaggerated calibration error would vary from the ideal over temperature. 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 10 shows a typical AD590K temperature curve before and after calibration error trimming. 2 IOUT (µA) ACTUAL TRANSFER FUNCTION IACTUAL CALIBRATION ERROR 298.2 IDEAL TRANSFER FUNCTION BEFORE CALIBRATION TRIM CALIBRATION ERROR 0 AFTER CALIBRATION TRIM –2 00533-008 CALIBRATION ERROR ERROR VS. TEMPERATURE: CALIBRATION ERROR TRIMMED OUT ABSOLUTE ERROR (°C) The AD590 is a PTAT 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. –55 150 TEMPERATURE (°C) 00533-006 Figure 10. Effect to Scale Factor Trim on Accuracy 298.2 TEMPERATURE (°K) Figure 8. Calibration Error vs. Temperature The calibration error is a primary contributor to the maximum total error in all AD590 grades. However, because it is a scale factor error, it is particularly easy to trim. Figure 9 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 VS. 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 11 shows the nonlinearity of the typical AD590K from Figure 10. 1 T(°C) = T(K) − 273.2. Zero on the Kelvin scale is absolute zero; there is no lower temperature. Rev. E | Page 7 of 16 AD590 VOLTAGE AND THERMAL ENVIRONMENT EFFECTS The power supply rejection specifications show the maximum expected change in output current vs. 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 10). 00533-009 –0.8 –1.6 –55 150 TEMPERATURE (°C) Figure 11. Nonlinearity Figure 12 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 output with the sensor at 100°C. Other pairs of temperatures can 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 14 is a model of the AD590 that demonstrates these characteristics. TJ TC θCA + 15V P 35.7kΩ AD581 θJC R1 2kΩ 97.6kΩ CCH R2 5kΩ CC – TA 00533-012 ABSOLUTE ERROR (°C) 1.6 Figure 14. Thermal Circuit Model 30pF 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 AD707A 00533-010 AD590 V– Figure 12. 2-Temperature Trim TJ − TA = P(θJC + θCA) 0 –2 00533-011 TEMPERATURE (°C) 2 –55 0 100 TEMPERATURE (°C) 150 (1) 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 is used, the scale factor trim compensates for this effect over the entire temperature range. Figure 13. Typical 2-Trim Accuracy Rev. E | Page 8 of 16 AD590 Table 4. Thermal Resistance 45 115 – 190 5.0 13.5 – 10.0 191 480 – 650 108 60 – 30 TFINAL T(t) = TINITIAL + (TFINAL – TINITIAL) × (1 – e–t/τ) 00533-013 τ (sec)1 H F 0.6 0.1 1.4 0.6 SENSED TEMPERATURE Medium Aluminum Block Stirred Oil2 Moving Air3 With Heat Sink Without Heat Sink Still Air With Heat Sink Without Heat Sink θJC + θCA (°C/Watt) H F 30 10 42 60 1 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. 2 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 15 is usually sufficient to describe the time response, T (t). Table 4 shows the effective time constant, τ, for several media. Rev. E | Page 9 of 16 TINITIAL τ 4τ TIME Figure 15. Time Response Curve AD590 GENERAL APPLICATIONS V+ Figure 16 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, Pin 9, Pin 4, and Pin 2 are grounded; for Fahrenheit temperature, Pin 4 and Pin 2 are left open. R3 10kΩ + AD590L #2 – – + 8 9 OFFSET CALIBRATION AD2040 4 GAIN SCALING 6 AD590 – 5 GND Figure 16. 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 17, 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 19 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 19, 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 – + AD580 333.3Ω (0.1%) + VT AVG – – 00533-015 + VT MIN CONSTANTAN AD590 AD590 – IRON REFERENCE JUNCTION 52.3Ω VOUT 8.66kΩ RT 1kΩ Figure 17. Series and Parallel Connection The circuit in Figure 18 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 00533-017 AD590 10kΩ (0.1%) (T1 – T2) × (10mV/°C) + R4 10kΩ V– OFFSET SCALING 2 3 R2 50kΩ Figure 18. Differential Measurements 00533-014 + AD707A R1 5MΩ 00533-016 AD590L #1 – 5V Figure 19. Cold Junction Compensation Circuit for Type J Thermocouple Rev. E | Page 10 of 16 AD590 20pF Figure 20 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 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 can be chosen. 1.25kΩ AD581 – VOUT AD590 30pF BIT 2 BIT 7 200Ω, 15T +5V BIT 3 BIT 6 +2.5V BIT 4 BIT 5 + – AD590 – AD707A – + 12.7kΩ +5V 10kΩ AD580 200Ω +5V 1kΩ 3 8 LM311 2 1 4 –15V 5kΩ 7 OUTPUT HIGHTEMPERATURE ABOVE SETPOINT OUTPUT LOWTEMPERATURE BELOW SETPOINT 5.1MΩ –15V 500Ω 6.8kΩ 10Ω Figure 22. DAC Setpoint 00533-018 0.01µF BIT 8 1kΩ, 15T RT 5kΩ + 1.15kΩ BIT 1 6.98kΩ 35.7kΩ +5V 00533-020 + MC 1408/1508 DAC OUT V+ 4mA = 17°C 12mA = 25°C 20mA = 33°C REF –15V V– Figure 20. 4 to 20 mA Current Transmitter Figure 21 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. The voltage compliance and the reverse blocking characteristic of the AD590 allow it to be powered directly from 5 V CMOS logic. This permits easy multiplexing, switching, or pulsing for minimum internal heat dissipation. In Figure 23, 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 can be employed for other purposes, but the additional capacitance due to the AD590 should be taken into account. 5V V+ V+ AD581 OUT + 10V V– RH AD590 + – RSET RB 2 HEATING ELEMENTS + + 1 – AD590 – – – 4 1kΩ (0.1%) GND 00533-021 10kΩ 00533-019 3 + C1 + 7 – LM311 RL CMOS GATES Figure 21. Simple Temperature Control Circuit Figure 23. AD590 Driven from CMOS Logic Figure 22 shows that the AD590 can be configured with an 8-bit DAC to produce a digitally controlled setpoint. 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. Rev. E | Page 11 of 16 AD590 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 24 shows a circuit that combines the principle demonstrated in Figure 23 with an 8-channel CMOS multiplexer. The resulting circuit can select 1 to 80 sensors over only 18 wires with a 7-bit binary word. The inhibit input on the multiplexer turns all sensors off for minimum dissipation while idling. Figure 25 demonstrates a method of multiplexing the AD590 in the 2-trim mode (see Figure 12 and Figure 13). Additional AD590s and their associated resistors can be added to multiplex 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. 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 00533-022 10kΩ 10mV/°C Figure 24. 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 25. 8-Channel Multiplexer Rev. E | Page 12 of 16 00533-023 AD581 2kΩ AD590 OUTLINE DIMENSIONS 0.030 (0.76) TYP POSITIVE LEAD INDICATOR 0.019 (0.48) 0.017 (0.43) 0.015 (0.38) 0.093 (2.36) 0.081 (2.06) 0.055 (1.40) 0.050 (1.27) 0.045 (1.14) 0.500 (12.69) MIN 0.240 (6.10) 0.230 (5.84) 0.220 (5.59) 0.0065 (0.17) 0.0050 (0.13) 0.0045 (0.12) 0.210 (5.34) 0.200 (5.08) 0.190 (4.83) 0.050 (1.27) 0.041 (1.04) 0.015 (0.38) TYP Figure 26. 2-Lead Ceramic Flat Package [FLATPACK] (F-2) Dimensions shown in inches and (millimeters) 0.150 (3.81) 0.115 (2.92) 0.500 (12.70) MIN 0.250 (6.35) MIN 0.050 (1.27) T.P. 0.100 (2.54) T.P. 0.019 (0.48) 0.016 (0.41) 0.030 (0.76) MAX 0.048 (1.22) 0.028 (0.71) 3 0.195 (4.95) 0.178 (4.52) 0.021 (0.53) MAX 2 0.050 (1.27) T.P. 0.046 (1.17) 0.036 (0.91) 1 45° T.P. BASE & SEATING PLANE CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN. Figure 27. 3-Pin Metal Header Package [TO-52] (H-03-1) Dimensions shown in inches and (millimeters) Rev. E | Page 13 of 16 022306-A 0.230 (5.84) 0.209 (5.31) 0.050 (1.27) MAX AD590 5.00 (0.1968) 4.80 (0.1890) 8 1 5 4 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) COPLANARITY 0.10 SEATING PLANE 6.20 (0.2441) 5.80 (0.2284) 1.75 (0.0688) 1.35 (0.0532) 0.51 (0.0201) 0.31 (0.0122) 0.50 (0.0196) 0.25 (0.0099) 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-A A 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 4.00 (0.1574) 3.80 (0.1497) Figure 28. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches) ORDERING GUIDE Model AD590JF 1 AD590JH1 AD590JR AD590JRZ 2 AD590JRZ-RL2 AD590KF1 AD590KH1 AD590KR AD590KR-REEL AD590KRZ2 AD590KRZ-RL2 AD590LF1 AD590LH1 AD590MF1 AD590MH1 AD590JCHIPS 1 2 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 −55°C to +150°C −55°C to +150°C −55°C to +150°C Package Description 2-Lead FLATPACK 3-Pin TO-52 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 2-Lead FLATPACK 3-Pin TO-52 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 2-Lead FLATPACK 3-Pin TO-52 2-Lead FLATPACK 3-Pin TO-52 3-Pin TO-52 Available in 883B; consult sales for data sheet. Z = RoHS Compliant Part. Rev. E | Page 14 of 16 Package Option F-2 H-03-1 R-8 R-8 R-8 F-2 H-03-1 R-8 R-8 R-8 R-8 F-2 H-03-1 F-2 H-03-1 H-03-1 AD590 NOTES Rev. E | Page 15 of 16 AD590 NOTES ©2006–2009 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D00533-0-9/09(E) Rev. E | Page 16 of 16