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functional block diagram 1 2 3 d out v+ gnd vptat v ref temperature sensor digital modulator tmp03/tmp04 rev. a 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 which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of analog devices. a serial digital output thermometers features low cost 3-pin package modulated serial digital output proportional to temperature 1.5 c accuracy (typ) from C25 c to +100 c specified C40 c to +100 c, operation to 150 c power consumption 6.5 mw max at 5 v flexible open-collector output on tmp03 cmos/ttl-compatible output on tmp04 low voltage operation (4.5 v to 7 v) applications isolated sensors environmental control systems computer thermal monitoring thermal protection industrial process control power system monitors tmp03/tmp04 * package types available to-92 1 2 3 d out v+ gnd bottom view (not to scale) tmp03/tmp04 so-8 and ru-8 (tssop) 1 2 3 4 8 7 6 5 top view (not to scale) nc = no connect tmp03/ tmp04 d out nc nc nc nc v+ gnd nc general description the tmp03/tmp04 are monolithic temperature detectors that generate a modulated serial digital output that varies in direct proportion to the temperature of the device. an onboard sensor generates a voltage precisely proportional to absolute tempera- ture which is compared to an internal voltage reference and input to a precision digital modulator. the ratiometric encoding format of the serial digital output is independent of the clock drift errors common to most serial modulation techniques such as voltage-to-frequency converters. overall accuracy is 1.5 c (typical) from ?5 c to +100 c, with excellent transducer lin- earity. the digital output of the tmp04 is cmos/ttl compatible, and is easily interfaced to the serial inputs of most popular microprocessors. the open-collector output of the tmp03 is capable of sinking 5 ma. the tmp03 is best suited for systems requiring isolated circuits utilizing optocouplers or isolation transformers. the tmp03 and tmp04 are specified for operation at supply voltages from 4.5 v to 7 v. operating from 5 v, supply current (unloaded) is less than 1.3 ma. the tmp03/tmp04 are rated for operation over the ?0 c to +100 c temperature range in the low cost to-92, so-8, and tssop-8 surface mount packages. operation extends to 150 c with reduced accuracy. (continued on page 4) * patent pending. one technology way, p.o. box 9106, norwood, ma 02062-9106, u.s.a. tel: 781/329-4700 world wide web site: http://www.analog.com fax: 781/326-8703 ? analog devices, inc., 2002
parameter symbol conditions min typ max unit accuracy temperature error ?5 c < t a < +100 c 1 1.5 4.0 c ?0 c < t a < ?5 c 1 2.0 5.0 c temperature linearity 0.5 c long-term stability 1000 hours at 125 c 0.5 c nominal mark-space ratio t1/t2 t a = 0 c 58.8 % nominal t1 pulsewidth t1 10 ms power supply rejection ratio psrr over rated supply 0.7 1.4 c/v t a = 25 c outputs output low voltage v ol i sink = 1.6 ma 0.2 v output low voltage v ol i sink = 5 ma 2 v 0 c < t a < 100 c output low voltage v ol i sink = 4 ma 2 v ?0 c < t a < 0 c digital output capacitance c out (note 2) 15 pf fall time t hl see test load 150 ns device turn-on time 20 ms power supply supply range v+ 4.5 7 v supply current i sy unloaded 0.9 1.3 ma notes 1 maximum deviation from output transfer function over specified temperature range. 2 guaranteed but not tested. specifications subject to change without notice. test load 10 k ? to 5 v supply, 100 pf to ground tmp04f parameter symbol conditions min typ max unit accuracy temperature error t a = 25 c 1.0 3.0 c ?5 c < t a < +100 c 1 1.5 4.0 c ?0 c < t a < ?5 c 1 2.0 5.0 c temperature linearity 0.5 c long-term stability 1000 hours at 125 c 0.5 c nominal mark-space ratio t1/t2 t a = 0 c 58.8 % nominal t1 pulsewidth t1 10 ms power supply rejection ratio psrr over rated supply 0.7 1.2 c/v t a = 25 c outputs output high voltage v oh i oh = 800 a v+ ?.4 v output low voltage v ol i ol = 800 a 0.4 v digital output capacitance c out (note 2) 15 pf fall time t hl see test load 200 ns rise time t lh see test load 160 ns device turn-on time 20 ms power supply supply range v+ 4.5 7 v supply current i sy unloaded 0.9 1.3 ma notes 1 maximum deviation from output transfer function over specified temperature range. 2 guaranteed but not tested. specifications subject to change without notice. test load 100 pf to ground rev. a tmp03/tmp04?pecifications tmp03f (v+ = 5 v, ?0 c t a 100 c, unless otherwise noted.) C2C (v+ = 5 v, ?0 c t a 100 c, unless otherwise noted.)
tmp03/tmp04 rev. a C3C warning! esd sensitive device 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 tmp03 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. absolute maximum ratings * maximum supply voltage . . . . . . . . . . . . . . . . . . . . . . . . . 9 v maximum output current (tmp03 d out ) . . . . . . . . . 50 ma maximum output current (tmp04 d out ) . . . . . . . . . 10 ma maximum open-collector output voltage (tmp03) . . . 18 v operating temperature range . . . . . . . . . . ?5 c to +150 c dice junction temperature . . . . . . . . . . . . . . . . . . . . . . 175 c storage temperature range . . . . . . . . . . . . ?5 c to +160 c lead temperature (soldering, 60 sec) . . . . . . . . . . . . . 300 c * caution 1 stresses above those listed under absolute maximum ratings may cause perma- nent damage to the device. this is a stress rating only; functional operation at or above this specification is not implied. exposure to the above maximum rating conditions for extended periods may affect device reliability. 2 digital inputs and outputs are protected, however, permanent damage may occur on unprotected units from high-energy electrostatic fields. keep units in conduc- tive foam or packaging at all times until ready to use. use proper antistatic handling procedures. 3 remove power before inserting or removing units from their sockets. package type ja jc units to-92 (t9) 162 1 120 c/w so-8 (s) 158 1 43 c/w tssop (ru) 240 1 43 c/w note 1 ja is specified for device in socket (worst case conditions). ordering guide accuracy temperature model at 25 c range package tmp03ft9 3.0 xind to-92 tmp03fs 3.0 xind so-8 tmp03fru 3.0 xind tssop-8 tmp04ft9 3.0 xind to-92 tmp04fs 3.0 xind so-8
tmp03/tmp04 rev. a C4C (continued from page 1) the tmp03 is a powerful, complete temperature measurement system with digital output, on a single chip. the onboard tem- perature sensor follows in the footsteps of the tmp01 low power programmable temperature controller, offering excellent accuracy and linearity over the entire rated temperature range without correction or calibration by the user. the sensor output is digitized by a first-order sigma-delta modulator, also known as the ?harge balance?type analog-to- digital converter. (see figure 1.) this type of converter utilizes time-domain oversampling and a high accuracy comparator to deliver 12 bits of effective accuracy in an extremely compact circuit. voltage ref and vptat clock generator comparator 1-bit dac integrator modulator digital filter tmp03/04 out (single-bit) figure 1. tmp03 block diagram showing first-order sigma-delta modulator basically, the sigma-delta modulator consists of an input sampler, a summing network, an integrator, a comparator, and a 1-bit dac. similar to the voltage-to-frequency converter, this architecture creates in effect a negative feedback loop whose intent is to minimize the integrator output by changing the duty cycle of the comparator output in response to input voltage changes. the comparator samples the output of the integrator at a much higher rate than the input sampling frequency, called oversampling. this spreads the quantization noise over a much wider band than that of the input signal, improving overall noise performance and increasing accuracy. the modulated output of the comparator is encoded using a circuit technique (patent pending) which results in a serial digi- tal signal with a mark-space ratio format that is easily decoded by any microprocessor into either degrees centigrade or degrees fahrenheit values, and readily transmitted or modulated over a single wire. most importantly, this encoding method neatly avoids major error sources common to other modulation tech- niques, as it is clock-independent. output encoding accurate sampling of an analog signal requires precise spacing of the sampling interval in order to maintain an accurate repre- sentation of the signal in the time domain. this dictates a master clock between the digitizer and the signal processor. in the case of compact, cost-effective data acquisition systems, the addition of a buffered, high speed clock line can represent a significant burden on the overall system design. alternatively, the addition of an onboard clock circuit with the appropriate accuracy and drift performance to an integrated circuit can add significant cost. the modulation and encoding techniques uti- lized in the tmp03 avoid this problem and allow the overall circuit to fit into a compact, 3-pin package. to achieve this, a simple, compact onboard clock and an oversampling digitizer that is insensitive to sampling rate variations are used. most importantly, the digitized signal is encoded into a ratiometric format in which the exact frequency of the tmp03? clock is irrelevant, and the effects of clock variations are effectively can- celed upon decoding by the digital filter. the output of the tmp03 is a square wave with a nominal frequency of 35 hz ( 20%) at 25 c. the output format is readily decoded by the user as follows: t1 t2 figure 2. tmp03 output format temperature ( c) = 235 ? 400 t 1 t 2 ? ? ? ? ? ? temperature ( f) = 455 ? 720 t 1 t 2 ? ? ? ? ? ? the time periods t1 (high period) and t2 (low period) are values easily read by a microprocessor timer/counter port, with the above calculations performed in software. since both peri- ods are obtained consecutively, using the same clock, performing the division indicated in the above formulas results in a ratiometric value that is independent of the exact frequency of, or drift in, either the originating clock of the tmp03 or the user s counting clock.
tmp03/tmp04 rev. a C5C table i. counter size and clock frequency effects on quantization error maximum maximum maximum quantization quantization count available temp required frequency error (25 c) error (77 f) 4096 125 c 94 khz 0.284 c 0.512 f 8192 125 c 188 khz 0.142 c 0.256 f 16384 125 c 376 khz 0.071 c 0.128 f optimizing counter characteristics counter resolution, clock rate, and the resultant temperature decode error that occurs using a counter scheme may be deter- mined from the following calculations: 1. t1 is nominally 10 ms, and compared to t2 is relatively insensitive to temperature changes. a useful worst-case assumption is that t1 will never exceed 12 ms over the specified temperature range. t1 max = 12 ms substituting this value for t1 in the formula, temperature ( c) = 235 ([t1/t2] 400), yields a maximum value of t2 of 44 ms at 125 c. rearranging the formula allows the maximum value of t2 to be calculated at any maximum operating temperature: t2 (temp) = (t1max 400)/(235 temp) in seconds 2. we now need to calculate the maximum clock frequency we can apply to the gated counter so it will not overflow during t2 time measurement. the maximum frequency is calculated using: frequency (max) = counter size/ (t2 at maximum temperature) substituting in the equation using a 12-bit counter gives, fmax = 4096/44 ms 94 khz. 3. now we can calculate the temperature resolution, or quanti- zation error, provided by the counter at the chosen clock frequency and temperature of interest. again, using a 12-bit counter being clocked at 90 khz (to allow for ~5% tempera- ture over-range), the temperature resolution at 25 c is calculated from: quantization error ( c) = 400 ([count 1 /count 2 ] [count 1 ? 1 ]/[count 2 + 1 ]) quantization error ( f) = 720 ([count 1 /count 2 ] [count 1 ? 1 ]/[count 2 + 1 ]) where, count1 = t1max frequency, and count2 = t2 (temp) frequency. at 25 c this gives a resolution of better than 0.3 c. note that the temperature resolution calculated from these equations improves as temperature increases. higher temperature resolution will be obtained by employing larger counters as shown in table i. the internal quantization error of the tmp03 sets a theoretical minimum resolution of approximately 0.1 c at 25 c. self-heating effects the temperature measurement accuracy of the tmp03 may be degraded in some applications due to self-heating. errors intro- duced are from the quiescent dissipation, and power dissipated by the digital output. the magnitude of these temperature er- rors is dependent on the thermal conductivity of the tmp03 package, the mounting technique, and effects of airflow. static dissipation in the tmp03 is typically 4.5 mw operating at 5 v with no load. in the to-92 package mounted in free air, this accounts for a temperature increase due to self-heating of ? t = p diss ja = 4.5 mw 162 c/w = 0.73 c (1.3 f ) for a free-standing surface-mount tssop package, the tem- perature increase due to self-heating would be ? t = p diss ja = 4.5 mw 240 c/w = 1.08 c (1.9 f ) in addition, power is dissipated by the digital output which is capable of sinking 800 a continuous (tmp04). under full load, the output may dissipate p diss = 0.6 v () 0.8 ma () t 2 t 1 + t 2 ? ? ? ? ? ? for example, with t2 = 20 ms and t1 = 10 ms, the power dissipation due to the digital output is approximately 0.32 mw with a 0.8 ma load. in a free-standing tssop package, this accounts for a temperature increase due to output self-heating of ? t = p diss ja = 0.32 mw 240 c/w = 0.08 c (0.14 f ) this temperature increase adds directly to that from the quies- cent dissipation and affects the accuracy of the tmp03 relative to the true ambient temperature. alternatively, when the same package has been bonded to a large plate or other thermal mass (effectively a large heatsink) to measure its temperature, the total self-heating error would be reduced to approximately ? t = p diss jc = (4.5 mw + 0.32 mw ) 43 c/w = 0.21 c (0.37 f ) calibration the tmp03 and tmp04 are laser-trimmed for accuracy and linearity during manufacture and, in most cases, no further adjustments are required. however, some improvement in per- formance can be gained by additional system calibration. to perform a single-point calibration at room temperature, measure the tmp03 output, record the actual measurement tempera- ture, and modify the offset constant (normally 235; see the output encoding section) as follows: offset constant = 235 + ( t observed t tmp03output ) a more complicated 2-point calibration is also possible. this involves measuring the tmp03 output at two temperatures, temp1 and temp2, and modifying the slope constant (normally 400) as follows: slope constant = temp 2 ? temp 1 t 1@ temp 1 t 2@ temp 1 ? ? ? ? ? ? ? t 1@ temp 2 t 2@ temp 2 ? ? ? ? ? ? where t 1 and t 2 are the output high and output low times, respectively.
temperature c 0 ?5 output frequency ?hz 10 v+ = 5v r load = 10k 20 30 40 50 60 70 ?5 25 75 125 175 tpc 1. output frequency vs. temperature temperature c 0 75 time ms 5 v s = 5v r load = 10k 10 15 20 25 30 35 25 25 75 125 175 40 45 t1 t2 tpc 2. t1 and t2 times vs. temperature time scale = 250ns/div voltage scale = 2v/div sample ( t ) t a = 25 c v dd = 5v c load = 100pf r load = 1k running: 200ms/s et ch 1 +width s wfm does not cross ref ch 1 width s wfm does not cross ref ch 1 rise s no valid edge ch 1 fall 209.6ns tpc 3. tmp03 output fall time at 25 c supply voltage volts 0.97 4.5 normalized output frequency t a = 25 c r load = 10k 5 5.5 6 6.5 7 7.5 0.98 0.99 1.00 1.01 1.02 1.03 1.04 1.05 tpc 4. n ormalized output frequency vs. supply voltage time scale = 1 s/div voltage scale = 2v/div sample ( t ) t a = 25 c v dd = 5v c load = 100pf r load = 1k running: 50.0ms/s ch 1 +width s wfm does not cross ref ch 1 width s wfm does not cross ref ch 1 rise 500ns ch 1 fall s no valid edge tpc 5. tmp03 output rise time at 25 c time scale = 1 s/div voltage scale = 2v/div sample ( t ) t a = 125 c v dd = 5v c load = 100pf r load = 1k running: 50.0ms/s ch 1 +width s wfm does not cross ref ch 1 width s wfm does not cross ref ch 1 rise 5380ns ch 1 fall s no valid edge tpc 6. tmp03 output rise time at 125 c rev. a C6C tmp03/tmp04?ypical performance characteristics
tmp03/tmp04 rev. a C7C ch 1 fall 139.5ns ch 1 rise s no valid edge ch 1 width s wfm does not cross ref ch 1 +width s wfm does not cross ref time scale = 250ns/div voltage scale = 2v/div sample ( t ) t a = 125 c v dd = 5v c load = 100pf r load = 1k running: 200ms/s et edge slope tpc 7. tmp03 output fall time at 125 c time scale = 250ns/div voltage scale = 2v/div sample ( t ) t a = 25 c v dd = 5v c load = 100pf r load = 0 running: 200ms/s et ch 1 +width s wfm does not cross ref ch 1 width s wfm does not cross ref ch 1 rise s no valid edge ch 1 fall 127.6ns tpc 8. tmp04 output fall time at 25 c time scale = 250ns/div voltage scale = 2v/div sample ( t ) t a = 125 c v dd = 5v c load = 100pf r load = 0 running: 200ms/s et ch 1 +width s wfm does not cross ref ch 1 width s wfm does not cross ref ch 1 rise s no valid edge ch 1 fall 188.0ns tpc 9. tmp04 output fall time at 125 c time scale = 250ns/div voltage scale = 2v/div sample ( t ) t a = 25 c v dd = 5v c load = 100pf r load = 0 running: 200ms/s et ch 1 +width s wfm does not cross ref ch 1 width s wfm does not cross ref ch 1 rise 110.6ns ch 1 fall s no valid edge tpc 10. tmp04 output rise time at 25 c time scale = 250ns/div voltage scale = 2v/div sample ( t ) t a = 125 c v dd = 5v c load = 100pf r load = 0 running: 200ms/s et ch 1 +width s wfm does not cross ref ch 1 width s wfm does not cross ref ch 1 rise 149.6ns ch 1 fall s no valid edge tpc 11. tmp04 output rise time at 125 c load capacitance pf 0 0 time ns t a = 25 c v s = 5v r load = 500 1000 1500 2000 2500 3000 500 1000 1500 2000 2500 3500 4000 4500 5000 fal l time rise time tpc 12. tmp04 output rise and fall times vs. capacitive load
tmp03/tmp04 rev. a C8C temperature c 5 50 output accuracy c 25 0 25 50 75 100 4 3 2 1 0 125 1 2 3 5 4 v+ = 5v r load = 10k tmp03 tmp04 maximum limit minimum limit measurements in stirred oil bath tpc 13. output accuracy vs. temperature time ms v+ 0 v+ = 5v r load = 10k 10 20 30 40 50 55 15 10 25 20 10 125 35 10 typical values temp t2 t1 c ms ms t1 t2 0, t1 t1 t2 output starts low output starts high 60 70 80 90 100 0, t2 tpc 14. start-up response temperature c 750 75 supply current a v+ = 5v no load 25 25 75 125 175 800 850 900 950 1000 1050 1100 tmp03 tmp04 tpc 15. supply current vs. temperature temperature c 3 75 start-up supply voltage volts 25 25 75 125 175 3.5 4 4.5 5 r load = 10k start-up voltage defined as output reading being within 5 c of output at 4.5v supply tpc 16. start-up voltage vs. temperature supply voltage volts 0 0 supply current a t a = 25 c no load 1 2 3 4 5 200 400 600 800 1000 1200 1400 678 1600 tpc 17. supply current vs. supply voltage temperature c 0 75 power supply rejection c/v 25 25 75 125 175 0.5 1 1.5 2 v+ = 4.5v to 7v r load = 10k 2.5 3.5 3 4 tpc 18. power supply rejection vs. temperature
tmp03/tmp04 rev. a C9C deviation in temperature c frequency hz 1 1 1 10 0 0.5 0.5 100 1k 100k 1m 10m 10k normal pssr v+ = 5v dc 50mv ac r load = 10k tpc 19. power supply rejection vs. frequency temperature c 0 75 open-collector output voltage mv 25 25 75 125 175 50 100 150 200 v+ = 5v 250 350 300 400 i load = 5ma i load = 1ma i load = 0.5ma tpc 20. tmp03 open-collector output voltage vs. temperature air velocity fpm 0 0 time constant sec 100 200 300 400 500 20 40 60 80 v+ = 5v r load = 10k 100 140 120 transition from 100 c oil bath to forced 25 c air soic - no socket 600 700 to 92 - with socket to 92 - no socket tpc 21. thermal time constant in forced air temperature c 2 75 sink current ma 25 25 75 125 150 8 10 12 14 v ol = 1v v+ = 5v 16 20 18 6 4 ')1"" '()*#/.1
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time sec 25 0 output temperature c 25 50 75 100 125 30 35 v s = 5v r load = 10k 105 100 transition from 100 c stirred oil bath to still 25 c air 150 175 soic to 92 ~ 23 sec (soic, no socket) ~ 40 sec (to 92, no socket) 40 45 50 55 60 65 70 75 80 85 90 95 200 225 250 275 300 tpc 23. thermal response time in still air time sec 25 0 output temperature c 10 20 30 40 50 v+ = 5v r load = 10k 100 transition from still 25 c air to stirred 100 c oil bath 60 soic to 92 1.25 sec (soic in socket) 2 sec (to 92 in socket) ')1"$ '
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tmp03/tmp04 rev. a C10C applications information supply bypassing precision analog products, such as the tmp03, require a well- filtered power source. since the tmp03 operate from a single 5 v supply, it seems convenient to simply tap into the digital logic power supply. unfortunately, the logic supply is often a switch- mode design, which generates noise in the 20 khz to 1 mhz range. in addition, fast logic gates can generate glitches hundred of millivolts in amplitude due to wiring resistance and induc- tance. if possible, the tmp03 should be powered directly from the system power supply. this arrangement, shown in figure 3, will isolate the analog section from the logic switching transients. even if a separate power supply trace is not available, however, gener- ous supply bypassing will reduce supply-line induced errors. local supply bypassing consisting of a 10 f tantalum electro- lytic in parallel with a 0.1 f ceramic capacitor is recommended (figure 4a). ttl/cmos logic circuits tmp03/ tmp04 10 f tant 0.1 f 5v power supply + figure 3. use separate traces to reduce power supply noise tmp03/ tmp04 10 f 0.1 f v+ d out gnd 5v tmp03/ tmp04 10 f 0.1 f v+ d out gnd 5v 50 a. b. figure 4. recommended supply bypassing for the tmp03 the quiescent power supply current requirement of the tmp03 is typically only 900 a. the supply current will not change appreciably when driving a light load (such as a cmos gate), so a simple rc filter can be added to further reduce power supply noise (figure 4b). tmp03 output configurations the tmp03 (figure 5a) has an open-collector npn output which is suitable for driving a high current load, such as an opto-isolator. since the output source current is set by the pull- up resistor, output capacitance should be minimized in tmp03 applications. otherwise, unequal rise and fall times will skew the pulsewidth and introduce measurement errors. the npn tran- sistor has a breakdown voltage of 18 v. v+ d out d out tmp03 tmp04 a. b. figure 5. tmp03 digital output structure the tmp04 has a totem-pole cmos output (figure 5b) and provides rail-to-rail output drive for logic interfaces. the rise and fall times of the tmp04 output are closely matched, so that errors caused by capacitive loading are minimized. if load ca- pacitance is large, for example when driving a long cable, an external buffer may improve accuracy. see the remote tem- perature measurement section of this data sheet for suggestions. interfacing the tmp03 to low voltage logic the tmp03 s open-collector output is ideal for driving logic gates that operate from low supply voltages, such as 3.3 v. as shown in figure 6, a pull-up resistor is connected from the low voltage logic supply (2.9 v, 3 v, etc.) to the tmp03 output. current through the pull-up resistor should be limited to about 1 ma, which will maintain an output low logic level of <200 mv. tmp03 5v d out gnd 3.3v 3.3k v+ to low voltage logic gate input figure 6. interfacing to low voltage logic remote temperature measurement when measuring a temperature in situations where high com- mon-mode voltages exist, an opto-isolator can be used to isolate the output (figure 7a). the tmp03 is recommended in this application because its open-collector npn transistor has a higher current sink capability than the cmos output of the tmp04. to maintain the integrity of the measurement, the opto-isolator must have relatively equal turn-on and turn-off times. some darlington opto-isolators, such as the 4n32, have a turn-off time that is much longer than their turn-on time. in this case, the t1 time will be longer than t2, and an erroneous reading will result. a pnp transistor can be used to provide greater current drive to the opto-isolator (figure 7b). an opto- isolator with an integral logic gate output, such as the h11l1 from quality technology, can also be used (figure 8).
tmp03/tmp04 rev. a C11C d out tmp03 5v v logic gnd 4.7k v+ opto-coupler 620 a. d out tmp03 5v v logic gnd 430 v+ opto-coupler 270 4.3k 10k 2n2907 b. figure 7. optically isolating the digital output d out tmp03 5v gnd 4.7k v+ h11l1 680 5v figure 8. an opto-isolator with schmitt trigger logic gate improves output rise and fall times the tmp03 and tmp04 are superior to analog-output trans- ducers for measuring temperature at remote locations, because the digital output provides better noise immunity than an analog signal. when measuring temperature at a remote location, the ratio of the output pulses must be maintained. to maintain the integrity of the pulsewidth, an external buffer can be added. for example, adding a differential line driver such as the adm485 permits precise temperature measurements at distances up to 4000 ft. (figure 9). the adm485 driver and receiver skew is only 5 ns maximum, so the tmp04 duty cycle is not degraded. up to 32 adm485s can be multiplexed onto one line by pro- viding additional decoding. as previously mentioned, the digital output of the tmp03 provides excellent noise immunity in remote measurement appli- cations. the user should be aware, however, that heat from an external cable can be conducted back to the tmp03. this heat conduction through the connecting wires can influence the temperature of the tmp03. if large temperature differences exist within the sensor environment, an opto-isolator, level shifter or other thermal barrier can be used to minimize measure- ment errors. d out tmp04 5v gnd v+ adm485 a b v cc de di nc 5v figure 9. a differential line driver for remote tempera- ture measurement microcomputer interfaces the tmp03 output is easily decoded with a microcomputer. the microcomputer simply measures the t1 and t2 periods in software or hardware, and then calculates the temperature using the equation in the output encoding section of this data sheet. since the tmp03 s output is ratiometric, precise control of the counting frequency is not required. the only timing require- ments are that the clock frequency be high enough to provide the required measurement resolution (see the output encoding section for details) and that the clock source be stable. the ratiometric output of the tmp03 is an advantage because the microcomputer s crystal clock frequency is often dictated by the serial baud rate or other timing considerations. pulsewidth timing is usually done with the microcomputer s on-chip timer. a typical example, using the 80c51, is shown in figure 10. this circuit requires only one input pin on the micro- computer, which highlights the efficiency of the tmp04 s pulsewidth output format. traditional serial input protocols, with data line, clock and chip select, usually require three or more i/o pins. d out tmp04 5v gnd v+ input port 1.0 osc 12 timer 0 (16-bits) timer 1 (16-bits) 80c51 microcomputer tmod register tcon register timer 0 timer 1 timer 0 timer 1 figure 10. a tmp04 interface to the 80c51 microcomputer the 80c51 has two 16-bit timers. the clock source for the timers is the crystal oscillator frequency divided by 12. thus, a crystal frequency of 12 mhz or greater will provide resolution of 1 s or less. the 80c51 timers are controlled by two dedicated registers. the tmod register controls the timer mode of operation, while tcon controls the start and stop times. both the tmod and tcon registers must be set to start the timer.
tmp03/tmp04 rev. a C12C listing 1. an 80c51 software routine for the tmp04 ; ; test of a tmp04 interface to the 8051, ; using timer 0 and timer 1 to measure the duty cycle ; ; this program has three steps: ; 1. clear the timer registers, then wait for a low-to- ; high transition on input p1.0 (which is connected ; to the output of the tmp04). ; 2. when p1.0 goes high, timer 0 starts. the program ; then loops, testing p1.0. ; 3. when p1.0 goes low, timer 0 stops & timer 1 starts. the ; program loops until p1.0 goes low, when timer 1 stops ; and the tmp04? t1 and t2 values are stored in special ; function registers 8ah through 8dh (tl0 through th1). ; ; ; primary controls $mod51 $title(tmp04 interface, using t0 and t1) $pagewidth(80) $debug $object ; ; variable declarations ; port1 data 90h ;sfr register for port 1 ;tcon data 88h ;timer control ;tmod data 89h ;timer mode ;th0 data 8ch ;timer 0 hi byte ;th1 data 8dh ;timer 1 hi byte ;tl0 data 8ah ;timer 0 lo byte ;tl1 data 8bh ;timer 1 low byte ; ; org 100h ;arbitrary start ; read_tmp04: mov a,#00 ;clear the mov th0,a ; counters mov th1,a ; first mov tl0,a ; mov tl1,a ; wait_lo: jb port1.0,wait_lo ;wait for tmp04 output to go low mov a,#11h ;get ready to start timer0 mov tmod,a wait_hi: jnb port1.0,wait_hi ;wait for output to go high ; ;timer 0 runs while tmp04 output is high ; setb tcon.4 ;start timer 0 waittimer0: jb port1.0,waittimer0 clr tcon.4 ;shut off timer 0 ; ;timer 1 runs while tmp04 output is low ; setb tcon.6 ;start timer 1 waittimer1: jnb port1.0,waittimer1 clr tcon.6 ;stop timer 1 mov a,#0h ;get ready to disable timers mov tmod,a ret end software for the interface is shown in listing 1. the program monitors the tmp04 output, and turns the counters on and off to measure the duty cycle. the time that the output is high is mea- sured by timer 0, and the time that the output is low is m easured by timer 1. when the routine finishes, the results are available in special function registers (sfrs) 08ah through 08dh.
tmp03/tmp04 rev. a C13C when the read_tmp04 routine is called, the counter registers are cleared. the program sets the counters to their 16-bit mode, and then waits for the tmp04 output to go high. when the input port returns a logic high level, timer 0 starts. the timer continues to run while the program monitors the input port. when the tmp04 output goes low, timer 0 stops and timer 1 starts. timer 1 runs until the tmp04 output goes high, at which time the tmp04 interface is complete. when the subroutine ends, the timer values are stored in their respective sfrs and the tmp04 s temperature can be calculated in software. since the 80c51 operates asynchronously to the tmp04, there is a delay between the tmp04 output transition and the start of the timer. this delay can vary between 0 s and the execution time of the instruction that recognized the transition. the 80c51 s jump on port.bit instructions (jb and jnb) require 24 clock cycles for execution. with a 12 mhz clock, this pro- duces an uncertainty of 2 s (24 clock cycles/12 mhz) at each transition of the tmp04 output. the worst case condition occurs when t1 is 4 s shorter than the actual value and t2 is 4 s longer. for a 25 c reading ( room temperature ), the nominal error caused by the 2 s delay is only about 0.15 c. the tmp04 is also easily interfaced to digital signal processors (dsps), such as the adsp210x series. again, only a single i/o pin is required for the interface (figure 11). d out tmp04 5v gnd v+ fi (flag in) 10mhz n 16-bit down counter clock oscillator adsp-210x timer enable figure 11. interfacing the tmp04 to the adsp-210x digital signal processor the adsp2101 only has one counter, so the interface software differs somewhat from the 80c51 example. the lack of two counters is not a limitation, however, because the dsp archi- tecture provides very high execution speed. the adsp-2101 executes one instruction for each clock cycle, versus one instruc- tion for twelve clock cycles in the 80c51, so the adsp-2101 actually produces a more accurate conversion while using a lower oscillator frequency. the timer of the adsp2101 is implemented as a down counter. when enabled by means of a software instruction, the counter is decremented at the clock rate divided by a programmable pres- caler. loading the value n 1 into the prescaler register will divide the crystal oscillator frequency by n . for the circuit of figure 11, therefore, loading 4 into the prescaler will divide the 10 mhz crystal oscillator by 5 and thereby decrement the counter at a 2 mhz rate. the tmp04 output is ratiometric, of course, so the exact clock frequency is not important. a typical software routine for interfacing the tmp04 to the adsp2101 is shown in listing 2. the program begins by initial- izing the prescaler and loading the counter with 0ffff h . the adsp2101 monitors the fi flag input to establish the falling edge of the tmp04 output, and starts the counter. when the tmp04 output goes high, the counter is stopped. the counter value is then subtracted from 0ffff h to obtain the actual number of counts, and the count is saved. then the counter is reloaded and runs until the tmp04 output goes low. finally, the tmp04 pulsewidths are converted to temperature using the scale factor of equation 1. some applications may require a hardware interface for the tmp04. one such application could be to monitor the tempera- ture of a high power microprocessor. the tmp04 interface would be included as part of the system asic, so that the micro- processor would not be burdened with the overhead of timing the output pulsewidths. a typical hardware interface for the tmp04 is shown in figure 12. the circuit measures the output pulsewidths with a resolu- tion of 1 s. the tmp04 t1 and t2 periods are measured with two cascaded 74hc4520 8-bit counters. the counters, accumulating clock pulses from the 1 mhz external oscillator, have a maximum period of 65 ms. the logic interface is straightforward. on both the rising and falling edges of the tmp04 output, an exclusive-or gate gener- ates a pulse. this pulse triggers one half of a 74hc4538 dual one-shot. the pulse from the one-shot is anded with the tmp04 output polarity to store the counter contents in the appropriate output registers. the falling edge of this pulse also triggers the second one-shot, which generates a reset pulse for the counters. after the reset pulse, the counters will begin to count the next tmp04 output phase. as previously mentioned, the counters have a maximum period of 65 ms with a 1 mhz clock input. however, the tmp04 s t1 and t2 times will never exceed 32 ms. therefore, the most significant bit (msb) of counter #2 will not go high in nor- mal operation, and can be used to warn the system that an error condition (such as a broken connection to the tmp04) exists. the circuit of figure 12 will latch and save both the t1 and t2 times simultaneously. this makes the circuit suitable for debug- ging or test purposes as well as for a general purpose hardware interface. in a typical asic application, of course, one set of latches could be eliminated if the latch contents, and the output polarity, were read before the next phase reversal of the tmp04.
tmp03/tmp04 rev. a C14C { adsp-21xx temperature measurement routine temperat.dsp altered registers: ax0, ay0, af, ar, si, sr0, my0, mr0, mr1, mr2. return value: ar ? temperature result in 14.2 format computation time: 2 * tmp04 output period } .module/ram/boot=0 temperat; { beginning temperat program } .entry tempmeas; { entry point of this subroutine } .const prescaler=4; .const timfulscale=0xffff; tempmeas: si=prescaler; { for timer prescaler } sr0=timfulscale; { timer counter full scale } dm(0x3ffb)=si; { timer prescaler set up to 5 } si=timfulscale; { clkin=10mhz,timer period=32.768ms } dm(0x3ffc)=si; { timer counter register to 65535 } dm(0x3ffd)=si; { timer period register to 65535 } imask=0x01; { unmask interrupt timer } test1: if not fi jump test1; { check for fi=1 } test0: if fi jump test0; { check for fi=0 to locate transition } ena timer; { enable timer, count at a 500ns rate } count2: if not fi jump count2; { check for fi=1 to stop count } dis timer; ay0=dm(0x3ffc); { save counter=t2 in alu register } ar=sr0-ay0; ax0=ar; dm(0x3ffc)=si; { reload counter at full scale } ena timer; count1: if fi jump count1; { check for fi=0 to stop count } dis timer; ay0=dm(0x3ffc); { save counter=t1 in alu register } ar=sr0-ay0; my0=400; mr=ar * my0(uu); { mr=400 * t1 } ay0=mr0; { af=msw of dividend, ay0=lsw } ar=mr1; af=pass ar; { ax0=16-bit divisor } compute: astat=0; { to clear aq flag } divq ax0; divq ax0; { division 400 * t1/t2 } divq ax0; divq ax0; { with 0.3 < t1/t2 < 0.7 } divq ax0; divq ax0; divq ax0; divq ax0; divq ax0; divq ax0; divq ax0; divq ax0; divq ax0; divq ax0; divq ax0; divq ax0; divq ax0; divq ax0; { result in ay0 } ax0=0x03ac; { ax0=235 * 4 } ar=ax0-ay0; { ar=235-400 * t1/t2, result in ? } rts; { format 14.2 } .endmod; { end of the subprogram } listing 2. software routine for the tmp04-to-adsp-210x interface ;
tmp03/tmp04 rev. a C15C monitoring electronic equipment the tmp03 are ideal for monitoring the thermal environment within electronic equipment. for example, the surface-mounted package will accurately reflect the exact thermal conditions which affect nearby integrated circuits. the to-92 package, on the other hand, can be mounted above the surface of the board, to measure the temperature of the air flowing over the board. the tmp03 and tmp04 measure and convert the temperature at the surface of their own semiconductor chip. when the tmp03 are used to measure the temperature of a nearby heat source, the thermal impedance between the heat source and the tmp03 must be considered. often, a thermocouple or other tempera- ture sensor is used to measure the temperature of the source d out tmp04 gnd t1 t2 v cc clr b a q q 5v 5v 0.1 f 74hc4538 gnd out 1 10 74hc373 v cc le d1 d2 d3 d4 d5 d6 d7 d8 q1 q2 q3 q4 q5 q6 q7 q8 2 5 6 9 12 15 16 19 3 4 7 8 13 14 17 18 20 11 5v 3 1 2 3 1 2 5 4 74hc08 1 74hc4520 #1 v cc clk q0 q1 q2 q3 q0 q1 q2 q3 3 4 5 6 11 12 13 14 9 7 815 16 5v 10 en en 2 clk gnd reset reset 10 3 13 8 12 11 74hc373 v cc le d1 d2 d3 d4 d5 d6 d7 d8 q1 q2 q3 q4 q5 q6 q7 q8 2 5 6 9 12 15 16 19 3 4 7 8 13 14 17 18 20 11 5v 74hc373 v cc le d1 d2 d3 d4 d5 d6 d7 d8 q1 q2 q3 q4 q5 q6 q7 q8 2 5 6 9 12 15 16 19 3 4 7 8 13 14 17 18 20 11 5v 74hc373 v cc le d1 d2 d3 d4 d5 d6 d7 d8 q1 q2 q3 q4 q5 q6 q7 q8 2 5 6 9 12 15 16 19 3 4 7 8 13 14 17 18 20 11 5v 74hc4520 #2 v cc q0 q1 q2 q3 q0 q1 q2 q3 3456 11121314 17 9 15 16 5v 10 en en 2 clk gnd reset reset 1mhz clock 6 t1 data (microseconds) t2 data (microseconds) gnd t1 t2 clr b a q q 5v 5v 10 f gnd v+ 5v 20pf 3.9k 9 15 14 16 6 7 5 8 4 1k 20pf 74hc86 10pf 10k 4 5 6 nc nc clk 8 gnd out 1 10 gnd out 1 10 gnd out 1 10 figure 12. a hardware interface for the tmp04 while the tmp03 temperature is monitored by measuring t1 and t2. once the thermal impedance is determined, the tem- perature of the heat source can be inferred from the tmp03 output. one example of using the tmp04 to monitor a high power dissipation microprocessor or other ic is shown in figure 13. the tmp04, in a surface mount package, is mounted directly beneath the microprocessor s pin grid array (pga) package. in a typical application, the tmp04 s output would be connected to an asic where the pulsewidth would be measured (see the hardware interface section of this data sheet for a typical inter- face schematic). the tmp04 pulse output provides a significant
tmp03/tmp04 rev. a C16C c00334C0C1/02(a) printed in u.s.a. outline dimensions dimensions shown in inches and (mm). 3-pin to-92 0.105 (2.66) 0.080 (2.42) 0.105 (2.66) 0.080 (2.42) 0.165 (4.19) 0.125 (3.94) square 0.019 (0.482) 0.016 (0.407) 0.105 (2.66) 0.095 (2.42) 0.055 (1.39) 0.045 (1.15) seating plane 0.500 (12.70) min 0.205 (5.20) 0.175 (4.96) 0.210 (5.33) 0.170 (4.38) 12 3 bottom view 0.135 (3.43) min 0.050 (1.27) max 8-pin soic (so-8) 85 4 1 0.1968 (5.00) 0.1890 (4.80) 0.2440 (6.20) 0.2284 (5.80) pin 1 0.1574 (4.00) 0.1497 (3.80) 0.0500 (1.27) bsc 0.0688 (1.75) 0.0532 (1.35) seating plane 0.0098 (0.25) 0.0040 (0.10) 0.0192 (0.49) 0.0138 (0.35) 0.0098 (0.25) 0.0075 (0.19) 0.0500 (1.27) 0.0160 (0.41) 8 0 0.0196 (0.50) 0.0099 (0.25) 45 8-pin tssop (ru-8) 8 5 4 1 0.256 (6.50) 0.246 (6.25) 0.177 (4.50) 0.169 (4.30) pin 1 0.0256 (0.65) bsc 0.122 (3.10) 0.114 (2.90) seating plane 0.006 (0.15) 0.002 (0.05) 0.0118 (0.30) 0.0075 (0.19) 0.0433 (1.10) max 0.0079 (0.20) 0.0035 (0.090) 0.028 (0.70) 0.020 (0.50) 8 0 advantage in this application because it produces a linear tem- perature output while needing only one i/o pin and without requiring an a/d converter. pc board tmp04 in surface mount package fast microprocessor, dsp, etc., in pga package pga socket figure 13. monitoring the temperature of a high power microprocessor improves system reliability thermal response time the time required for a temperature sensor to settle to a speci- fied accuracy is a function of the thermal mass of, and the thermal conductivity between, the sensor and the object being sensed. thermal mass is often considered equivalent to capaci- tance. thermal conductivity is commonly specified using the symbol , and can be thought of as thermal resistance. it is commonly specified in units of degrees per watt of power trans- ferred across the thermal joint. thus, the time required for the tmp03 to settle to the desired accuracy is dependent on the package selected, the thermal contact established in that par- ticular application, and the equivalent power of the heat source. in most applications, the settling time is probably best deter- mined empirically. the tmp03 output operates at a nominal frequency of 35 hz at 25 c, so the minimum settling time reso- lution is 27 ms.

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