TMP17F/G-SPECIFICATIONS (V = 5.0 V, -40C T 105C, unless otherwise noted.) S Parameter Symbol A Conditions ACCURACY TMP17F TMP17G TMP17F TMP17G Min Typ TA = 25C1 TA = 25C1 Over Rated Temperature Over Rated Temperature POWER SUPPLY REJECTION RATIO 4 V < VS < 5 V 5 V < VS < 15 V 15 V < VS < 30 V Nonlinearity POWER SUPPLY Supply Range Unit 2.5 3.5 3.5 4.5 C C C C 0.5 0.3 0.3 Over Rated Temperature2 0.5 C/V C/V C/V C TA = 25C (298.2 K) Over Rated Temperature Note 3 TA = 150C for 500 Hrs4 298.2 1 0.2 0.2 A A/C C C/month PSRR PSRR PSRR OUTPUT Nominal Current Output Scale Factor Repeatability Long Term Stability Max +VS 4 30 V NOTES 1 An external calibration trim can be used to zero the error @ 25 C. 2 Defined as the maximum deviation from a mathematically best fit line. 3 Maximum deviation between 25C readings after a temperature cycle between -40C and +105C. Errors of this type are noncumulative. 4 Operation at 150C. Errors of this type are noncumulative. Specifications subject to change without notice. METALLIZATION DIAGRAM ABSOLUTE MAXIMUM RATINGS* Maximum Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . 30 V Operating Temperature Range . . . . . . . . . . . -40C to +105C Maximum Forward Voltage (1 to 2) . . . . . . . . . . . . . . . . . 44 V Maximum Reverse Voltage (2 to 1) . . . . . . . . . . . . . . . . . . 20 V Dice Junction Temperature . . . . . . . . . . . . . . . . . . . . . . 175C Storage Temperature Range . . . . . . . . . . . . . -65C to +160C Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . . . 300C 62mils V+ 37mils *Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only and functional operation at or above this specification is not implied. Exposure to the above maximum rating conditions for extended periods may affect device reliability. V- TEMPERATURE SCALE CONVERSION EQUATIONS K C +223 -50 F -100 +273 +298 +323 0 +25 +50 0 C = +32 5 (F - 32) 9 +100 +200 +70 F = +373 +100 ORDERING GUIDE +423 +150 Model +300 TMP17FS 2.5C TMP17GS 3.5C +212 9 C + 32 5 Max Cal Error @ +25C K = C + 273.15 Max Error Nonlinearity -40C to -40C to Package +105C +105C Option 3.5C 4.5C 0.5C 0.5C R-8 R-8 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 the TMP17 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. -2- REV. A Typical Performance Characteristics-TMP17 6 500 5 IOUT = 378A 400 3 OUTPUT CURRENT - A TEMPERATURE ERROR - C CONSTANT IOUT UP TO 30V 450 MAX LIMIT V+ = +5V 4 1 2 1 2 3 0 -1 -2 4 5 -3 350 IOUT = 298A 300 IOUT = 233A 250 TA = +105C 200 TA = +25C 150 100 -4 TA = -40C MIN LIMIT -5 -6 -50 -25 0 25 50 TEMPERATURE - C 75 50 100 0 125 TPC 1. Accuracy vs. Temperature 0 1 2 3 4 SUPPLY VOLTAGE - V 5 TPC 4. V-I Characteristics 100 90 80 PERCENT OF CHANGE - % 2s V+ = +5V SOIC PACKAGE SOLDERED TO 0.5" 0.3" Cu PCB 70 100 90 60 50 40 30 10 0% 20 200mV 10 0 0 5 10 15 TIME - sec 20 25 30 TPC 2. Thermal Response in Stirred Oil Bath TPC 5. Output Turn-On Settling Time 60 TRANSITION FROM 100C STIRRED BATH TO FORCED 25C AIR V = 5V 50 TIME CONSTANT - sec SOIC PACKAGE SOLDERED TO 0.5" 0.3" Cu PCB 40 30 20 10 0 0 100 200 300 400 AIR VELOCITY - FPM 500 600 TPC 3. Thermal Time Constant in Forced Air REV. A VIN = 0V TO 5V RL = 1k TA = 25C -3- 6 TMP17 0.2 THEORY OF OPERATION The TMP17 uses a fundamental property of silicon transistors to realize its temperature proportional output. If two identical transistors are operated at a constant ratio of collector current densities, r, then the difference in base-emitter voltages will be (kT/q)(ln r). Since both k, Boltzmann's constant, and q, the charge of an electron, are constant, the resulting voltage is directly Proportional to Absolute Temperature (PTAT). In the TMP17, this difference voltage is converted to a PTAT current by low temperature coefficient thin film resistors. This PTAT current is then used to force the total output current to be proportional to degrees Kelvin. The result is a current source with an output equal to a scale factor times the temperature (K) of the sensor. A typical V-I plot of the circuit at 125C and the temperature extremes is shown in TPC 4. TYPICAL NONLINEARITY NONLINEARITY - C 0.1 0 -0.1 -0.2 -0.3 -40 Factory trimming of the scale factor to 1 A/K is accomplished at the wafer level by adjusting the TMP17's temperature reading so it corresponds to the actual temperature. During laser trimming, the IC is at a temperature within a few degrees of 25C and is powered by a 5 V supply. The device is then packaged and automatically temperature tested to specification. -25 0 25 TEMPERATURE - C 70 105 Figure 2. Nonlinearity Error TRIMMING FOR HIGHER ACCURACY Calibration error at 25C can be removed with a single temperature trim. Figure 3 shows how to adjust the TMP17's scale factor in the basic voltage output circuit. FACTORS AFFECTING TMP17 SYSTEM PRECISION +V The accuracy limits in the Specifications table make the TMP17 easy to apply in a variety of diverse applications. To calculate a total error budget in a given system, it is important to correctly interpret the accuracy specifications, nonlinearity errors, the response of the circuit to supply voltage variations, and the effect of the surrounding thermal environment. As with other electronic designs, external component selection will have a major effect on accuracy. + TMP17 - + R 100 VOUT = 1mV/K 950 - Figure 3. Basic Voltage Output (Single Temperature Trim) CALIBRATION ERROR, ABSOLUTE ACCURACY, AND NONLINEARITY SPECIFICATIONS To trim the circuit, the temperature must be measured by a reference sensor and the value of R should be adjusted so the output (VOUT) corresponds to 1 mV/K. Note that the trim procedure should be implemented as close as possible to the temperature for which highest accuracy is desired. In most applications, if a single temperature trim is desired, it can be implemented where the TMP17 current-to-output voltage conversion takes place (e.g., output resistor, offset to an op amp). Figure 4 illustrates the effect on total error when using this technique. Two primary limits of error are given for the TMP17 such that the correct grade for any given application can easily be chosen for the overall level of accuracy required. They are the calibration accuracy at +25C and the error over temperature from -40C to +105C. These specifications correspond to the actual error the user would see if the current output of a TMP17 were converted to a voltage with a precision resistor. Note that the maximum error at room temperature or over an extended range, including the boiling point of water, can be read directly from the Specifications table. The error limits are a combination of initial error, scale factor variation, and nonlinearity deviation from the ideal 1 A/K output. TPC 1 graphically depicts the guaranteed limits of accuracy for a TMP17GS. 1.0 ACCURACY WITHOUT TRIM TOTAL ERROR - C 0.5 The TMP17 has a highly linear output in comparison to older technology sensors (i.e., thermistors, RTDs, and thermocouples), thus a nonlinearity error specification is separated from the absolute accuracy given over temperature. As a maximum deviation from a best-fit straight line, this specification represents the only error that cannot be trimmed out. Figure 2 is a plot of typical TMP17 nonlinearity over the full rated temperature range. 0 AFTER SINGLE TEMPERATURE CALIBRATION -0.5 -1.0 -40 -25 0 25 TEMPERATURE - C 105 Figure 4. Effect of Scale Factor Trim on Accuracy -4- REV. A TMP17 If greater accuracy is desired, initial calibration and scale factor errors can be removed by using the TMP17 in the circuit of Figure 5. +5V 8.66k 97.6k R1 1k under several conditions. Table I shows how the magnitude of self-heating error varies relative to the environment. In typical free air applications at 25C with a 5 V supply, the magnitude of the error is 0.2C or less. A small glued-on heat sink will reduce the temperature error in high temperature, large supply voltage situations. R2 5k REF43 OP196 7.87k + TMP17 Table I. Thermal Characteristics + VOUT = 100mV/C - - V- Figure 5. Two Temperature Trim Circuit JA (C/W) (sec)* Still Air Moving Air @ 500 FPM Fluorinert Liquid 158 60 35 52 10 2 * is an average of one time constant (63.2% of final value). In cases where the thermal response is not a simple exponential function, the actual thermal response may be better than indicated. With the transducer at 0C, adjustment of R1 for a 0 V output nulls the initial calibration error and shifts the output from K to C. Tweaking the gain of the circuit at an elevated temperature by adjusting R2 trims out scale factor error. The only error remaining over the temperature range being trimmed for is nonlinearity. A typical plot of two trim accuracy is given in Figure 6. Response of the TMP17 output to abrupt changes in ambient temperature can be modeled by a single time constant exponential function. TPC 2 and TPC 3 show typical response time plots for media of interest. The time constant, , is dependent on JA and on the thermal capacities of the chip and the package. Table I lists the effective (time to reach 63.2% of the final value) for several different media. Copper printed circuit board connections will sink or conduct heat directly through the TMP17's soldered leads. When faster response is required, a thermally conductive grease or glue between the TMP17 and the surface temperature being measured should be used. 0.2 0.1 TOTAL ERROR - C Medium 0 -0.1 MOUNTING CONSIDERATIONS If the TMP17 is thermally attached and properly protected, it can be used in any temperature measuring situation where the maximum range of temperatures encountered is between -40C and +105C. Thermally conductive epoxy or glue is recommended under typical mounting conditions. In wet environments, condensation at cold temperatures can cause leakage current related errors and should be avoided by sealing the device in nonconductive epoxy paint or conformal coating. -0.2 -0.3 -40 -25 0 25 TEMPERATURE - C 75 105 Figure 6. Typical Two Trim Accuracy SUPPLY VOLTAGE AND THERMAL ENVIRONMENT EFFECTS APPLICATIONS The power supply rejection characteristics of the TMP17 minimize errors due to voltage irregularity, ripple, and noise. If a supply is used other than 5 V (used in factory trimming), the power supply error can be removed with a single temperature trim. The PTAT nature of the TMP17 will remain unchanged. The general insensitivity of the output allows the use of lower cost unregulated supplies and means that a series resistance of several hundred ohms (e.g., CMOS multiplexer, meter coil resistance) will not degrade the overall performance. Connecting several TMP17 devices in parallel adds the currents through them and produces a reading proportional to the average temperature. TMP17s connected in series will indicate the lowest temperature, because the coldest device limits the series current flowing through the sensors. Both of these circuits are depicted in Figure 7. +15V +5V TMP17 The thermal environment in which the TMP17 is used determines two performance traits: the effect of self-heating on accuracy and the response time of the sensor to rapid changes in temperature. In the first case, a rise in the IC junction temperature above the ambient temperature is a function of two variables: the power consumption level of the circuit and the thermal resistance between the chip and the ambient environment (JA). Self-heating error in C can be derived by multiplying the power dissipation by JA. Because errors of this type can vary widely for surroundings with different heat sinking capacities, it is necessary to specify JA REV. A + + + + - - - - + TMP17 TMP17 - + TMP17 333.3 (0.1%) VTAVG (1mV/1K) - 10k (0.1%) VTAVG (10mV/1K) Figure 7. Average and Minimum Temperature Connections -5- TMP17 In this circuit the 1 A/K output of the TMP17 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 TMP17 may be chosen. The circuit in Figure 8 demonstrates a method in which a voltage output can be derived in a differential temperature measurement. +V 10k + TMP17 - + R1 50k TMP17 - 5M + OP196 10k +20V + VOUT = (T1 - T2 ) (10mV/C) 17C 33C REF01E - - -V 35.7k + 10mV/C TMP17 RT 5k 4mA 20mA 1mA/C OP97 - Figure 8. Differential Measurements R1 can be used to trim out the inherent offset between the two devices. By increasing the gain resistor (10 k), temperature measurements can be made with higher resolution. If the magnitude of V1 and V2 is not the same, the difference in power consumption between the two devices can cause a differential self-heating error. C +7.5V MEASURING JUNCTION REF43 Cu 1k 2.5V TMP17 Cu REFERENCE JUNCTION 500 + VT - -20V Figure 10. Temperature to 4 -20 mA Current Transmitter Reading temperature with a TMP17 in a microprocessor based system can be implemented with the circuit shown in Figure 11. APPROX. R VALUE 52 41 41 61 6 6 ROFFSET +5V R 2.5V REF43 C F RGAIN ROFFSET RGAIN 9 .1 k 100k 180k 9.8k RCAL + OP196 ROFFSET/R GAIN VOUT = 100mV/(C OR F) + 10k - TMP17 - + - 5k 10 Cold junction compensation (CJC) used in thermocouple signal conditioning can be implemented using a TMP17 in the circuit configuration of Figure 9. Expensive simulated ice baths or hard to trim, inaccurate bridge circuits are no longer required. THERMOCOUPLE TYPE J K T E S R 12.7k 10k OP193 100k RG2 (1k) VOUT V- Figure 11. Temperature to Digital Output RG1 By using a differential input A/D converter and choosing the current to voltage conversion resistor correctly, any range of temperatures (up to the 145C span the TMP17 is rated for) centered at any point can be measured using a minimal number of components. In this configuration, the system will resolve up to 1C. R Figure 9. Thermocouple Cold Junction Compensation The circuit shown can be optimized for any ambient temperature range or thermocouple type by simply selecting the correct value for the scaling resistor R. The TMP17 output (1 A/K) R should approximate the line best fit to the thermocouple curve (slope in V/C) over the most likely ambient temperature range. Additionally, the output sensitivity can be chosen by selecting the resistors RG1 and RG2 for the desired noninverting gain. The offset adjustment shown simply references the TMP17 to C. Note that the TC of the reference and the resistors are the primary contributors to error. Temperature rejection of 40 to 1 can be easily achieved using the above technique. A variable temperature controlling thermostat can easily be built using the TMP17 in the circuit in Figure 12. +15V 10V REF01E + RHIGH 62.7k - RSET 10k TMP17 RPULL-UP AD790 COMPARATOR TEMP > SETPOINT OUTPUT HIGH RHYST Although the TMP17 offers a noise immune current output, it is not compatible with process control/industrial automation current loop standards. Figure 10 is an example of a temperature to 4-20 mA transmitter for use with 40 V, 1 k systems. 10k C RLOW 27.3k TEMP < SETPOINT OUTPUT LOW (OPTIONAL) C Figure 12. Variable Temperature Thermostat -6- REV. A TMP17 RHIGH and RLOW determine the limits of temperature controlled by the potentiometer RSET. The circuit shown operates over the temperature range -25C to +105C. The reference maintains a constant set point voltage and ensures that approximately 7 V appear across the sensor. If it is necessary to guardband for extraneous noise, hysteresis can be added by tying a resistor from the output to the ungrounded end of RLOW. COLUMN SELECT ROW SELECT +15V 4028 BCD TO DECIMAL DECODER VOUT +15V + T8 T2 - + T1 - - S2 S8 EN 80-TMP17s To convert the TMP17 output to C or F, a single inexpensive reference and op amp can be used as shown in Figure 15. Although this circuit is similar to the two temperature trim circuit shown in Figure 5, there are two important differences. First, the gain resistor is fixed, alleviating the need for an elevated temperature trim. Acceptable accuracy can be achieved by choosing an inexpensive resistor with the correct tolerance. Second, the TMP17 calibration error can be trimmed out at a known convenient temperature (e.g., room temperature) with a single potentiometer adjustment. This step is independent of the gain selection. VOUT TMP17s S1 -15V Figure 14. Matrix Multiplexer AD7501 REMOTE +15V -15V DECODER/ DRIVER + 10k AD7501 8-CHANNEL MUX Multiple remote temperatures can be measured using several TMP17s with a CMOS multiplexer or a series of 5 V logic gates because of the device's current-mode output and supply-voltage compliance range. The on resistance of a FET switch or output impedance of a gate will not affect the accuracy, as long as 4 V is maintained across the transducer. Muxes and logic driving circuits should be chosen to minimize leakage current related errors. Figure 13 illustrates a locally controlled mux switching the signal current from several remote TMP17s. CMOS or TTL gates can also be used to switch the TMP17 supply voltages, with the multiplexed signal being transmitted over a single twisted pair to the load. 10k TTL DTL TO CMOS I/O EN CHANNEL SELECT ROFFSET +5V Figure 13. Remote Temperature Multiplexing To minimize the number of muxes required when a large number of TMP17s are being used, the circuit can be configured in a matrix. That is, a decoder can be used to switch the supply voltage to a column of TMP17s while a mux is used to control which row of sensors is being measured. The maximum number of TMP17s that can be used is the product of the number of channels of the decoder and mux. REF43 2.5V R C F ROFFSET RGAIN 9 .1 k 100k 180k 9.8k RCAL OP196 ROFFSET/R GAIN + VOUT = 100mV/(C OR F) + - - V- TMP17 Figure 15. Celsius or Fahrenheit Thermometer An example circuit controlling 80 TMP17s is shown in Figure 14. A 7-bit digital word is all that is required to select one of the sensors. The enable input of the multiplexer turns all the sensors off for minimum dissipation while idling. REV. A RGAIN -7- TMP17 OUTLINE DIMENSIONS 8-Lead Standard Small Outline Package [SOIC] Narrow Body (R-8) C00336-0-1/03(A) Dimensions shown in millimeters and (inches) 5.00 (0.1968) 4.80 (0.1890) 4.00 (0.1574) 3.80 (0.1497) 8 5 1 4 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) COPLANARITY SEATING 0.10 PLANE 6.20 (0.2440) 5.80 (0.2284) 1.75 (0.0688) 1.35 (0.0532) 0.51 (0.0201) 0.33 (0.0130) 0.50 (0.0196) 45 0.25 (0.0099) 8 0.25 (0.0098) 0 1.27 (0.0500) 0.41 (0.0160) 0.19 (0.0075) 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 Revision History Location Page 1/03--Data Sheet changed from REV. 0 to REV. A. Deleted Obsolete TPC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 PRINTED IN U.S.A. Updated OUTLINE DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 -8- REV. A