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| AD590 August 1997 2-Wire, Current Output Temperature Transducer Description The AD590 is an integrated-circuit temperature transducer which produces an output current proportional to absolute temperature. The device acts as a high impedance constant current regulator, passing 1A/oK for supply voltages between +4V and +30V. Laser trimming of the chip's thin film resistors is used to calibrate the device to 298.2A output at 298.2oK (25oC). The AD590 should be used in any temperature-sensing application between -55oC to 150oC 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 the simplest application, a resistor, a power source and any voltmeter can be used to measure temperature. In addition to temperature measurement, applications include temperature compensation or correction of discrete components, and biasing proportional to absolute temperature. 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 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. Features * Linear Current Output . . . . . . . . . . . . . . . . . . . . 1A/oK * Wide Temperature Range . . . . . . . . . . . -55oC to 150oC * Two-Terminal Device Voltage In/Current Out * Wide Power Supply Range . . . . . . . . . . . . . +4V to +30V * Sensor Isolation From Case * Low Cost Ordering Information NONPART LINEARITY TEMP. RANGE NUMBER (oC) (oC) AD590IH 3.0 1.5 -55 to 150 PKG. NO. T3.A PACKAGE 3 Ld Metal Can (TO-52) 3 Ld Metal Can (TO-52) AD590JH -55 to 150 T3.A Pinout AD590 (METAL CAN) Functional Diagram + R1 260 + Q2 Q6 C1 26pF R2 1040 Q5 Q3 Q4 1 3 CASE Q1 Q7 Q12 Q8 - 2 CHIP SUBSTRATE R3 5k Q10 1 R6 820 R5 146 R4 11k Q9 8 Q11 1 - CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. http://www.intersil.com or 407-727-9207 | Copyright (c) Intersil Corporation 1999 File Number 3171.1 12-3 AD590 Absolute Maximum Ratings TA = 25oC Thermal Information Thermal Resistance (Typical, Note 1) JA (oC/W) JC (oC/W) Metal Can Package . . . . . . . . . . . . . . . 200 120 Maximum Junction Temperature (Metal Can Package) . . . . . . . 175oC Maximum Storage Temperature Range . . . . . . . . . .-65oC to 150oC Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . . 300oC Supply Forward Voltage (V+ to V-) . . . . . . . . . . . . . . . . . . . . . . +44V Supply Reverse Voltage (V+ to V-) . . . . . . . . . . . . . . . . . . . . . . .-20V Breakdown Voltage (Case to V+ to V-) . . . . . . . . . . . . . . . . . . 200V Rated Performance Temperature Range TO-52. . . . -55oC to 150oC Operating Conditions Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . -55oC to 150oC CAUTION: Stresses above those listed in "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. NOTE: 1. JA is measured with the component mounted on an evaluation PC board in free air. Electrical Specifications PARAMETER Typical Values at TA = 25C, V+ = 5V, Unless Otherwise Specified TEST CONDITIONS AD590I 298.2 1.0 Notes 1, 5 -55oC to 150oC, Note 7 20.0 Max 5.8 Max Note 6 Notes 2, 6 Notes 3, 6 3.0 Max 0.1 Max 0.1 Max 40 10.0 Max 3.0 Max 1.5 Max 0.1 Max 0.1 Max 40 oC oC oC oC oC/Month AD590J 298.2 1.0 5.0 Max UNITS A A/oK oC Nominal Output Current at 2oC (298.2oK) Nominal Temperature Coefficient Calibration Error at 25oC Absolute Error Without External Calibration Adjustment With External Calibration Adjustment Non-Linearity Repeatability Long Term Drift Current Noise Power Supply Rejection +4V < V+ < +5V +5V < V+ < +15V +15V < V+ < +30V Case Isolation to Either Lead Effective Shunt Capacitance Electrical Turn-On Time Reverse Bias Leakage Current Power Supply Range NOTES: 2. Does not include self heating effects. Note 1 Note 4 10.0 Max pA/Hz 0.5 0.2 0.1 1010 100 20 10 +4 to +30 0.5 0.2 0.1 1010 100 20 10 +4 to +30 A/V A/V A/V pF s pA V 3. Maximum deviation between 25oC reading after temperature cycling between -55oC and 150oC. 4. Conditions constant +5V, constant 125oC. 5. Leakage current doubles every 10oC. 6. Mechanical strain on package may disturb calibration of device. 7. Guaranteed but not tested. 8. -55oC Guaranteed by testing at 25oC and 150oC. 12-4 AD590 Trimming Out Errors The ideal graph of current versus temperature for the AD590 is a straight line, but as Figure 1 shows, the actual shape is slightly different. Since the sensor is limited to the range of -55oC to 150oC, it is possible to optimize the accuracy by trimming. Trimming also permits extracting maximum performance from the lower-cost sensors. The circuit of Figure 2 trims the slope of the AD590 output. The effect of this is shown in Figure 3. The circuit of Figure 4 trims both the slope and the offset. This is shown in Figure 5. The diagrams are exaggerated to show effects, but it should be clear that these trims can be used to minimize errors over the whole range, or over any selected part of the range. In fact, it is possible to adjust the I-grade device to give less than 0.1oC error over the range 0oC to 90oC and less than 0.05oC error from 25oC to 60oC. IDEAL 35.7k R1 2k + AD590 VOUT = 100mV/ oC +10V 97.6k R2 5k VR1 = OFFSET R2 = SLOPE FIGURE 4. SLOPE AND OFFSET TRIMMING I (A) ACTUAL (GREATLY EXAGGERATED) FIGURE 5A. UNTRIMMED T (oK) FIGURE 1. TRIMMING OUT ERRORS +5V + + AD590 + R 100 VOUT = 1mV/ oK R = SLOPE 950 FIGURE 5B. TRIM ONE: OFFSET FIGURE 2. SLOPE TRIMMING IDEAL ACTUAL I (A) TRIMMED T (oK) FIGURE 5C. TRIM TWO: SLOPE FIGURE 3. EFFECT OF SLOPE TRIM 12-5 AD590 Accuracy Maximum errors over limited temperature spans, with VS = +5V, are listed by device grade in the following tables. The tables reflect the worst-case linearities, which invariably occur at the extremities of the specified temperature range. The trimming conditions for the data in the tables are shown in Figure 2 and Figure 4. All errors listed in the tables are oC. For example, if 1oC maximum error is required over the 25oC to 75oC range (i.e., lowest temperature of 25oC and span of 50oC), then the trimming of a J-grade device, using the single-trim circuit (Figure 2), will result in output having the required accuracy over the stated range. An I-grade device with two trims (Figure 4) will have less than 0.2oC error. If the requirement is for less than 1.4oC maximum error, from -25oC to 75oC (100oC span from -25oC), it can be satisfied by an I-grade device with two trims. FIGURE 5D. TRIM THREE: OFFSET AGAIN FIGURE 5. EFFECT OF SLOPE AND OFFSET TRIMMING I Grade Maximum Errors (oC) LOWEST TEMPERATURE IN SPAN (oC) NUMBER OF TRIMS None None None None None None One One One One One One Two Two Two Two Two Two NOTE: 9. Less than 0.05oC. TEMPERATURE SPAN (oC) 10 25 50 100 150 205 10 25 50 100 150 205 10 25 50 100 150 205 -55 8.4 10.0 13.0 15.2 18.4 20.0 0.6 1.8 3.8 4.8 5.5 5.8 0.3 0.5 1.2 1.8 2.6 3.0 -25 9.2 10.4 13.0 16.0 19.0 0.4 1.2 3.0 4.5 4.8 0.2 0.3 0.6 1.4 2.0 0 10.0 11.0 12.8 16.6 19.2 0.4 1.0 2.0 4.2 5.5 0.1 0.2 0.4 1.0 2.8 25 10.8 11.8 13.8 17.4 0.4 1.0 2.0 4.2 (Note 9) (Note 9) 0.2 2.0 50 11.6 12.0 14.6 18.8 0.4 1.0 2.0 5.0 (Note 9) 0.1 0.2 2.5 75 12.4 13.8 16.4 0.4 1.2 3.0 0.1 0.2 0.3 100 13.2 15.0 18.0 0.4 1.6 3.8 0.2 0.3 0.7 125 14.4 16.0 0.6 1.8 0.3 0.5 - 12-6 AD590 J Grade Maximum Errors (oC) NUMBER OF TRIMS None None None None None None One One One One One One Two Two Two Two Two Two NOTE: 10. Less than 0.05oC. TEMPERATURE SPAN (oC) 10 25 50 100 150 205 10 25 50 100 150 205 10 25 50 100 150 205 LOWEST TEMPERATURE IN SPAN (oC) -55 4.2 5.0 6.5 7.7 9.2 10.0 0.3 0.9 1.9 2.3 2.5 3.0 0.1 0.2 0.4 0.7 1.0 1.6 -25 4.6 5.2 6.5 8.0 9.5 0.2 0.6 1.5 2.2 2.4 (Note 10) 0.1 0.2 0.5 0.7 0 5.0 5.5 6.4 8.3 9.6 0.2 0.5 1.0 2.0 2.5 (Note 10) (Note 10) 0.1 0.3 1.2 25 5.4 5.9 6.9 8.7 0.2 0.5 1.0 2.0 (Note 10) (Note 10) (Note 10) 0.7 50 5.8 6.0 7.3 9.4 0.2 0.5 1.0 2.3 (Note 10) (Note 10) (Note 10) 1.0 75 6.2 6.9 8.2 0.2 0.6 1.5 (Note 10) (Note 10) 0.1 100 6.6 7.5 9.0 0.2 0.8 1.9 (Note 10) 0.1 0.2 125 7.2 8.0 0.3 0.9 0.1 0.2 (Note 10) - NOTES 1. Maximum errors over all ranges are guaranteed based on the known behavior characteristic of the AD590. 2. For one-trim accuracy specifications, the 205oC span is assumed to be trimmed at 25oC; for all other spans, it is assumed that the device is trimmed at the midpoint. 3. For the 205oC span, it is assumed that the two-trim temperatures are in the vicinity of 0oC and 140oC; for all other spans, the specified trims are at the endpoints. 4. In precision applications, the actual errors encountered are usually dependent upon sources of error which are often overlooked in error budgets. These typically include: a. Trim error in the calibration technique used b. Repeatability error c. Long term drift errors Trim Error is usually the largest error source. This error arises from such causes as poor thermal coupling between the device to be calibrated and the reference sensor; reference sensor errors; lack of adequate time for the device being calibrated to settle to the final temperature; radically different thermal resistances between the case and the surroundings (RCA) when trimming and when applying the device. Repeatability Errors arise from a strain hysteresis of the package. The magnitude of this error is solely a function of the magnitude of the temperature span over which the device is used. For example, thermal shocks between 0oC and 100oC involve extremely low hysteresis and result in repeatability errors of less than 0.05oC. When the thermalshock excursion is widened to -55oC to 150oC, the device will typIcally exhibit a repeatability error of 0.05oC (0.10 guaranteed maximum). Long Term Drift Errors are related to the average operating temperature and the magnitude of the thermal-shocks experienced by the device. Extended use of the AD590 at temperatures above 100oC typically results in long-term drift of 0.03oC per month; the guaranteed maximum is 0.10oC per month. Continuous operation at temperatures below 100oC induces no measurable drifts in the device. Besides the effects of operating temperature, the severity of thermal shocks incurred will also affect absolute stability. For thermal-shock excursions less than 100oC, the drift is difficult to measure (<0.03oC). However, for 200oC excursions, the device may drift by as much as 0.10oC after twenty such shocks. If severe, quick shocks are necessary in the application of the device, realistic simulated life tests are recommended for a thorough evaluation of the error introduced by such shocks. 12-7 AD590 Typical Applications +5V + +15V + + (ADDITIONAL SENSORS) + AD590 VOUT = 1mV/ oK 1k - - VOUT (AVG) = (R) i n - 333.3 0.1% (FOR 3 SENSORS) FIGURE 8. AVERAGE TEMPERATURE SENSING SCHEME FIGURE 6A. The sum of the AD590 currents appears across R, which is chosen by the formula: R = 10k , -------------n where n = the number of sensors. See Figure 8. OUTPUT CURRENT (A) 423 +15V 298.2 + AD590 218 RB LM311 3 R1 218oK (-55oC) 298.2oK (25oC) TEMPERATURE 423oK (150oC) R 0.1% 2 4 C R2 ICL8069 1.23V R VZERO 3 HEATER ELEMENT - 7 1 FIGURE 6B. FIGURE 6. SIMPLE CONNECTION. OUTPUT IS PROPORTIONAL TO ABSOLUTE TEMPERATURE FIGURE 9. SINGLE SETPOINT TEMPERATURE CONTROLLER +15V + + AD590 (AS MANY AS DESIRED) The AD590 produces a temperature-dependent voltage across R (C is for filtering noise). Setting R2 produces a scale-zero voltage. For the celsius scale, make R = 1k and VZERO = 0.273V. For Fahrenheit, R = 1.8k and VZERO = 0.460V. See Figure 9. 500A M + + 4V < VBATT <30V + AD590 VOUT (MIN) 10k 0.1% - FIGURE 7. LOWEST TEMPERATURE SENSING SCHEME. AVAILABLE CURRENT IS THAT OF THE "COLDEST" SENSOR FIGURE 10. SIMPLEST THERMOMETER Meter displays current output directly in degrees Kelvin. using the AD590J, sensor output is within 10 degrees over the entire range. See Figure 10. 12-8 - + AD590 V+ R1 REF HI R2 R R3 R4 R5 COMMON + AD590 IN LO REF LO The Kelvin scale version reads from 0 to 1999oK theoretically, and from 223oK to 473oK actually. The 2.26k resistor brings the input within the ICL7106 VCM range: 2 general-purpose silicon diodes or an LED may be substituted. See Figure 12 and notes below. ICL8069 1.235V 7.5k 12k ZERO ADJ 5k 1.000V 5k 15k 402 26.1k IN HI ICL7106 SCALE ADJ REF HI REF LO ICL7106 IN HI V+ V- FIGURE 11. BASIC DIGITAL THERMOMETER, CELSIUS AND FAHRENHEIT SCALES + 1k 0.1% COMMON IN LO AD590 R oF oC 5 R1 4.02 4.02 R2 2.0 2.0 R3 12.4 5.11 R4 10.0 5.0 R5 0 11.8 9.00 5.00 V- n=1 R n = 28k nominal FIGURE 13. BASIC DIGITAL THERMOMETER, KELVIN SCALE WITH ZERO ADJUST ALL values are in k. The ICL7106 has a VIN span of 2.0V and a VCM range of (V+ -0.5V) to (V- +1V). R is scaled to bring each range within VCM while not exceeding VIN . VREF for both scales is 500mV maximum rending on the celsius range 199.9oC limited by the (short-term) maximum allowable sensor temperature. Maximum reading on the fahrenheit range is 199.9oF (93.3oC) limited by the number of display digits. See Figure 11 and notes below. V+ 7.5k 5k 2.26k 15k SCALE ADJ This circuit allows "zero adjustment" as well as slope adjustment. the ICL8069 brings the input within the common-mode range, while the 5k pots trim any offset at 218oK (-55oC), and set the scale factor. See Figure 13 and notes below. Notes for Figure 11, Figure 12 and Figure 13 Since all 3 scales have narrow VlN spans, some optimization of ICL7106 components can be made to lower noise and preserve CMR. The table below shows the suggested values. Similar scaling can be used with the ICL7126 and ICL7136. SCALE VlN RANGE (V) 0.223 to 0.473 -0.25 to +1.0 -0.29 to +0.996 RlNT (k) 220 220 220 CAZ (F) 0.47 0.1 0.1 REF HI REF LO ICL7106 K C F IN HI 1.00k + AD590 COMMON IN LO For all: CREF = 0.1F ClNT = 0.22F COSC =100pF ROSC = 100k V- FIGURE 12. BASIC DIGITAL THERMOMETER, KELVIN SCALE 12-9 AD590 +15V + AD590 1k ZERO SET NO. 1 44.2k 10mV/ oC + ICL7611 V+ 5M 50k + NO. 2 + - (8V MIN) 118k 20k FULL-SCALE ADJUST M +100A V- 741 + 10k - - VOUT = (T2 - T1) x (10mV/ oC) 115k 10k 0.1% - 10k 100 10k 2.7315V - FIGURE 15. DIFFERENTIAL THERMOMETER FIGURE 14. CENTIGRADE THERMOMETER (0oC-100oC) The ultra-low bias current of the ICL7611 allows the use of large value gain resistors, keeping meter current error under 1/ %, and therefore saving the expense of an extra meter 2 driving amplifier. See Figure 14. The 50k pot trims offsets in the devices whether internal or external, so it can be used to set the size of the difference interval. this also makes it useful for liquid level detection (where there will be a measurable temperature difference). See Figure 15. The reference junction(s) should be in close thermal contact with the AD590 case. V+ must be at least 4V, while ICL8069 current should be set at 1mA - 2mA. Calibration does not require shorting or removal of the thermocouple: set R1 for V2 = 10.98mV. If very precise measurements are needed, adjust R2 to the exact Seebeck coefficient for the thermocouple used (measured or from table) note V1 , and set R1 to buck out this voltage (i.e., set V2 = V1). For other thermocouple types, adjust values to the appropriate Seebeck coefficient. See Figure 16. V+ + 1A/ oK - TC = 40V/ oK + V1 = 10.98mV SEEBECK COEFFICIENT = 40V/ oK TYPE K V+ + VOUT R2 40.2 1.235V R1 4521 40.2 ICL8069 4.7F V2 = 10.98mV FIGURE 16. COLD JUNCTION COMPENSATION FOR TYPE K THERMOCOUPLE 12-10 AD590 COLUMN SELECT +15V R (OPTIONAL) 13 8 D HI-0548 8-CHANNEL MUX 4 3 11 12 7 15 16 1 ENABLE +15V 2 13 ROW SELECT ENABLE 15 16 1 2 1 0 2 GND V- 7 14 3 9 6 10 5 2 6 1 5 0 4 4 0 5 1 6 2 HI-0548 8-CHANNEL MUX 3 7 12 4 11 5 10 6 9 7 D 8 R (OPTIONAL) VGND 14 3 10k 0.1% AD590 (64) VOUT FIGURE 17. MULTIPLEXING SENSORS If shorted sensors are possible, a series resistor in series with the D line will limit the current (shown as R, above: only one is needed). A six-bit digital word will select one of 64 sensors. 12-11 AD590 Die Characteristics DIE DIMENSIONS: 37 mils x 58 mils x 14 mils 1 mil METALLIZATION: Type: Aluminum 100% Thickness: 15kA 1kA PASSIVATION: Type: PSG/Nitride PSG Thickness: 7kA 1.4kA Nitride Thickness: 8kA 1.2kA Metallization Mask Layout AD590 All Intersil semiconductor products are manufactured, assembled and tested under ISO9000 quality systems certification. Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries. For information regarding Intersil Corporation and its products, see web site http://www.intersil.com 12-12 |
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