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a
FEATURES Low Cost 3-Pin Package Modulated Serial Digital Output Proportional to Temperature 1.5 C Accuracy (typ) from -25 C to +100 C Specified -40 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
Serial Digital Output Thermometers TMP03/TMP04*
FUNCTIONAL BLOCK DIAGRAM
TMP03/TMP04
TEMPERATURE SENSOR VPTAT DIGITAL MODULATOR
VREF
1 DOUT
2 V+
3 GND
PACKAGE TYPES AVAILABLE
TO-92
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 temperature 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 1.5C (typical) from -25C to +100C, with excellent transducer linearity. 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 -40C to +100C temperature range in the low cost TO-92, SO-8, and TSSOP-8 surface mount packages. Operation extends to 150C with reduced accuracy.
(continued on page 4) *Patent pending.
TMP03/TMP04
1 DOUT 2 V+ 3 GND
BOTTOM VIEW (Not to Scale)
SO-8 and RU-8 (TSSOP)
DOUT 1 V+ 2 GND 3
8 NC
TMP03/ TMP04
7 NC
TOP VIEW 6 NC (Not to Scale) 5 NC NC 4 NC = NO CONNECT
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. 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 (c) Analog Devices, Inc., 2002
TMP03/TMP04-SPECIFICATIONS
TMP03F (V+ = 5 V, -40 C T 100 C, unless otherwise noted.)
A
Parameter ACCURACY Temperature Error Temperature Linearity Long-Term Stability Nominal Mark-Space Ratio Nominal T1 Pulsewidth Power Supply Rejection Ratio OUTPUTS Output Low Voltage Output Low Voltage Output Low Voltage Digital Output Capacitance Fall Time Device Turn-On Time POWER SUPPLY Supply Range Supply Current
Symbol
Conditions -25C < TA < +100C1 -40C < TA < -25C1
Min
Typ 1.5 2.0 0.5 0.5 58.8 10 0.7
Max 4.0 5.0
Unit C C C C % ms C/V
T1/T2 T1 PSRR
1000 Hours at 125C TA = 0C Over Rated Supply TA = 25C ISINK = 1.6 mA ISINK = 5 mA 0C < TA < 100C ISINK = 4 mA -40C < TA < 0C (Note 2) See Test Load
1.4
VOL VOL VOL COUT tHL
0.2 2 2 15 150 20 4.5 7 1.3
V V V pF ns ms V mA
V+ ISY
Unloaded
0.9
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
(V+ = 5 V, -40 C TA 100 C, unless otherwise noted.)
Symbol Conditions TA = 25C -25C < TA < +100C1 -40C < TA < -25C1 T1/T2 T1 PSRR 1000 Hours at 125C TA = 0C Over Rated Supply TA = 25C IOH = 800 A IOL = 800 A (Note 2) See Test Load See Test Load V+ -0.4 0.4 15 200 160 20 4.5 Unloaded 0.9 7 1.3 Min Typ 1.0 1.5 2.0 0.5 0.5 58.8 10 0.7 Max 3.0 4.0 5.0 Unit C C C C C % ms C/V
ACCURACY Temperature Error Temperature Linearity Long-Term Stability Nominal Mark-Space Ratio Nominal T1 Pulsewidth Power Supply Rejection Ratio OUTPUTS Output High Voltage Output Low Voltage Digital Output Capacitance Fall Time Rise Time Device Turn-On Time POWER SUPPLY Supply Range Supply Current
1.2
VOH VOL COUT tHL tLH
V V pF ns ns ms V mA
V+ ISY
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
-2-
REV. A
TMP03/TMP04
ABSOLUTE MAXIMUM RATINGS* ORDERING GUIDE
Maximum Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . 9 V Maximum Output Current (TMP03 DOUT) . . . . . . . . . 50 mA Maximum Output Current (TMP04 DOUT) . . . . . . . . . 10 mA Maximum Open-Collector Output Voltage (TMP03) . . . 18 V Operating Temperature Range . . . . . . . . . . -55C to +150C Dice Junction Temperature . . . . . . . . . . . . . . . . . . . . . . 175C Storage Temperature Range . . . . . . . . . . . . -65C to +160C Lead Temperature (Soldering, 60 sec) . . . . . . . . . . . . . 300C
*CAUTION 1 Stresses above those listed under Absolute Maximum Ratings may cause permanent 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 conductive 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.
Model TMP03FT9 TMP03FS TMP03FRU TMP04FT9 TMP04FS
Accuracy at 25 C 3.0 3.0 3.0 3.0 3.0
Temperature Range XIND XIND XIND XIND XIND
Package TO-92 SO-8 TSSOP-8 TO-92 SO-8
Package Type TO-92 (T9) SO-8 (S) TSSOP (RU)
JA
JC 1
Units C/W C/W C/W
162 1581 2401
120 43 43
NOTE 1 JA is specified for device in socket (worst case conditions).
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.
WARNING!
ESD SENSITIVE DEVICE
REV. A
-3-
TMP03/TMP04
(continued from page 1)
The TMP03 is a powerful, complete temperature measurement system with digital output, on a single chip. The onboard temperature 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 "charge balance" type analog-todigital 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.
MODULATOR INTEGRATOR COMPARATOR VOLTAGE REF AND VPTAT
avoids major error sources common to other modulation techniques, as it is clock-independent.
Output Encoding
1-BIT DAC
Accurate sampling of an analog signal requires precise spacing of the sampling interval in order to maintain an accurate representation 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 utilized 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's clock is irrelevant, and the effects of clock variations are effectively canceled upon decoding by the digital filter. The output of the TMP03 is a square wave with a nominal frequency of 35 Hz ( 20%) at 25C. The output format is readily decoded by the user as follows:
T1 T2
CLOCK GENERATOR
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 digital 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
Figure 2. TMP03 Output Format
400 x T1 Temperature (C) = 235 - T2 720 x T1 Temperature (F) = 455 - T2 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 periods 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.
-4-
REV. A
TMP03/TMP04
Table I. Counter Size and Clock Frequency Effects on Quantization Error
Maximum Count Available 4096 8192 16384
Optimizing Counter Characteristics
Maximum Temp Required 125C 125C 125C
Maximum Frequency 94 kHz 188 kHz 376 kHz
Quantization Error (25 C) 0.284C 0.142C 0.071C
Quantization Error (77 F) 0.512F 0.256F 0.128F
Counter resolution, clock rate, and the resultant temperature decode error that occurs using a counter scheme may be determined 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] x 400), yields a maximum value of T2 of 44 ms at 125C. Rearranging the formula allows the maximum value of T2 to be calculated at any maximum operating temperature: T2 (Temp) = (T1max x 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 quantization 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% temperature over-range), the temperature resolution at 25C is calculated from: Quantization Error (C) = 400 x ([Count1/Count2] - [Count1 - 1]/[Count2 + 1]) Quantization Error (F) = 720 x ([Count1/Count2] - [Count1 - 1]/[Count2 + 1]) where, Count1 = T1max x Frequency, and Count2 = T2 (Temp) x Frequency. At 25C this gives a resolution of better than 0.3C. 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 0.1C at 25C.
Self-Heating Effects
with no load. In the TO-92 package mounted in free air, this accounts for a temperature increase due to self-heating of
T = PDISS x JA = 4.5 mW x 162C/W = 0.73C (1.3F)
For a free-standing surface-mount TSSOP package, the temperature increase due to self-heating would be
T = PDISS x JA = 4.5 mW x 240C/W = 1.08C (1.9F)
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 T2 P DISS = (0.6 V )(0.8 mA) T1 + 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 = PDISS x JA = 0.32 mW x 240C/W = 0.08C (0.14F)
This temperature increase adds directly to that from the quiescent 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 = PDISS x JC = (4.5 mW + 0.32 mW) x 43C/W = 0.21C (0.37F) 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 performance can be gained by additional system calibration. To perform a single-point calibration at room temperature, measure the TMP03 output, record the actual measurement temperature, and modify the offset constant (normally 235; see the Output Encoding section) as follows: Offset Constant = 235 + (TOBSERVED - TTMP03OUTPUT) 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 - Temp1 T1 @ Temp1 T1 @ Temp 2 - T 2 @ Temp1 T 2 @ Temp 2
The temperature measurement accuracy of the TMP03 may be degraded in some applications due to self-heating. Errors introduced are from the quiescent dissipation, and power dissipated by the digital output. The magnitude of these temperature errors 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 REV. A -5-
where T1 and T2 are the output high and output low times, respectively.
TMP03/TMP04-Typical Performance Characteristics
70
NORMALIZED OUTPUT FREQUENCY
1.05
V+ = 5V RLOAD = 10k
60
1.04 1.03 1.02 1.01 1.00 0.99 0.98 0.97 4.5
TA = 25 C RLOAD = 10k
OUTPUT FREQUENCY - Hz
50 40 30 20 10
0 -75
-25
25
75
125
175
5
5.5
6
6.5
7
7.5
TEMPERATURE - C
SUPPLY VOLTAGE - Volts
TPC 1. Output Frequency vs. Temperature
TPC 4. Normalized Output Frequency vs. Supply Voltage
45 40 35 T2 30
VOLTAGE SCALE = 2V/DIV
VS = 5V RLOAD = 10k
RUNNING: 50.0MS/s
SAMPLE
(T )
CH 1 +WIDTH s Wfm DOES NOT CROSS REF CH 1 -WIDTH s Wfm DOES NOT CROSS REF
TA = 25 C VDD = 5V
TIME - ms
25 20 15 T1 10 5
CLOAD = 100pF RLOAD = 1k
CH 1 RISE 500ns CH 1 FALL s NO VALID EDGE
TIME SCALE = 1 s/DIV
0 -75 -25 25 75 125 175
TEMPERATURE - C
TPC 2. T1 and T2 Times vs. Temperature
TPC 5. TMP03 Output Rise Time at 25C
RUNNING: 200MS/s ET
SAMPLE
(T )
CH 1 +WIDTH s Wfm DOES NOT CROSS REF CH 1 -WIDTH s Wfm DOES NOT CROSS REF
RUNNING: 50.0MS/s
SAMPLE
(T )
CH 1 +WIDTH s Wfm DOES NOT CROSS REF CH 1 -WIDTH s Wfm DOES NOT CROSS REF
VOLTAGE SCALE = 2V/DIV
TA = 25 C VDD = 5V
VOLTAGE SCALE = 2V/DIV
TA = 125 C VDD = 5V
CLOAD = 100pF RLOAD = 1k
CH 1 RISE s NO VALID EDGE CH 1 FALL 209.6ns
CLOAD = 100pF RLOAD = 1k
CH 1 RISE 5380ns CH 1 FALL s NO VALID EDGE
TIME SCALE = 250ns/DIV
TIME SCALE = 1 s/DIV
TPC 3. TMP03 Output Fall Time at 25C
TPC 6. TMP03 Output Rise Time at 125C
-6-
REV. A
TMP03/TMP04
RUNNING: 200MS/s ET SAMPLE
(T )
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 139.5ns
EDGE SLOPE
RUNNING: 200MS/s ET
SAMPLE
(T )
CH 1 +WIDTH s Wfm DOES NOT CROSS REF CH 1 -WIDTH s Wfm DOES NOT CROSS REF
VOLTAGE SCALE = 2V/DIV
TA = 125 C VDD = 5V
VOLTAGE SCALE = 2V/DIV
TA = 25 C VDD = 5V
CLOAD = 100pF RLOAD = 0
CH 1 RISE 110.6ns CH 1 FALL s NO VALID EDGE
CLOAD = 100pF RLOAD = 1k
TIME SCALE = 250ns/DIV
TIME SCALE = 250ns/DIV
TPC 7. TMP03 Output Fall Time at 125C
TPC 10. TMP04 Output Rise Time at 25 C
RUNNING: 200MS/s ET
SAMPLE
(T ) TA = 25 C VDD = 5V
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
RUNNING: 200MS/s ET
SAMPLE
(T )
CH 1 +WIDTH s Wfm DOES NOT CROSS REF CH 1 -WIDTH s Wfm DOES NOT CROSS REF
VOLTAGE SCALE = 2V/DIV
VOLTAGE SCALE = 2V/DIV
TA = 125 C VDD = 5V
CLOAD = 100pF RLOAD = 0
CLOAD = 100pF RLOAD = 0
CH 1 RISE 149.6ns CH 1 FALL s NO VALID EDGE
TIME SCALE = 250ns/DIV
TIME SCALE = 250ns/DIV
TPC 8. TMP04 Output Fall Time at 25C
TPC 11. TMP04 Output Rise Time at 125C
2500
RUNNING: 200MS/s ET SAMPLE
(T ) TA = 125 C VDD = 5V
CH 1 +WIDTH s Wfm DOES NOT CROSS REF
2000
TA = 25 C VS = 5V RLOAD = FAL L TIME
VOLTAGE SCALE = 2V/DIV
CLOAD = 100pF RLOAD = 0
CH 1 RISE s NO VALID EDGE CH 1 FALL 188.0ns
TIME - ns
CH 1 -WIDTH s Wfm DOES NOT CROSS REF
1500
1000 RISE TIME 500
TIME SCALE = 250ns/DIV
0
0
500
1000 1500 2000 2500 3000 3500 4000 4500 5000 LOAD CAPACITANCE - pF
TPC 9. TMP04 Output Fall Time at 125C
TPC 12. TMP04 Output Rise and Fall Times vs. Capacitive Load
REV. A
-7-
TMP03/TMP04
5 4 3 MAXIMUM LIMIT
5 START-UP VOLTAGE DEFINED AS OUTPUT READING BEING WITHIN 5 C OF OUTPUT AT 4.5V SUPPLY 4.5
OUTPUT ACCURACY - C
2 1
V+ = 5V RLOAD = 10k TMP03
MEASUREMENTS IN STIRRED OIL BATH
START-UP SUPPLY VOLTAGE - Volts
RLOAD = 10k 4
0 -1 -2 -3 -4 -5 -50 -25 0 MINIMUM LIMIT 50 25 TEMPERATURE - C 75 100 125 TMP04
3.5
3 -75
-25
25
75
125
175
TEMPERATURE - C
TPC 13. Output Accuracy vs. Temperature
TPC 16. Start-Up Voltage vs. Temperature
1600
V+ = 5V RLOAD = 10k
TYPICAL VALUES TEMP C -55 25 125 T1 T2 T2 ms 15 20 35 T1 ms 10 10 10
A
1400 1200 1000 800 600 400 200
TA = 25 C NO LOAD
0, T2 OUTPUT STARTS LOW 0, T1 OUTPUT STARTS HIGH T2 T1
V+ 0 10 20 30 40 50 60 70 80 90 100
SUPPLY CURRENT -
0
0
1
2
TIME - ms
3 5 4 SUPPLY VOLTAGE - Volts
6
7
8
TPC 14. Start-Up Response
TPC 17. Supply Current vs. Supply Voltage
1100 1050
A
4
V+ = 5V NO LOAD
3.5
POWER SUPPLY REJECTION - C/V
V+ = 4.5V TO 7V RLOAD = 10k
1000 950 900 TMP03 850 TMP04 800 750 -75
3 2.5 2 1.5 1 0.5 0 -75
SUPPLY CURRENT -
-25
25
75
125
175
-25
25
75
125
175
TEMPERATURE - C
TEMPERATURE - C
TPC 15. Supply Current vs. Temperature
TPC 18. Power Supply Rejection vs. Temperature
-8-
REV. A
TMP03/TMP04
1 V+ = 5V DC 50mV AC RLOAD = 10k 0.5
20 18 16
SINK CURRENT - mA
DEVIATION IN TEMPERATURE - C
VOL = 1V V+ = 5V
14 12 10 8 6 4
NORMAL PSSR 0
-0.5
-1 1
10
100
1k
10k
100k
1M
10M
2 -75
-25
FREQUENCY - Hz
75 25 TEMPERATURE - C
125
150
TPC 19. Power Supply Rejection vs. Frequency
TPC 22. TMP03 Open-Collector Sink Current vs. Temperature
400
105 100
V+ = 5V
OPEN-COLLECTOR OUTPUT VOLTAGE - mV
350 300
OUTPUT TEMPERATURE - C
ILOAD = 5mA 250 200 150 100 50 ILOAD = 0.5mA 0 -75 -25 25 75 125 175
95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 0 SOIC 25 50
TRANSITION FROM 100 C STIRRED OIL BATH TO STILL 25 C AIR VS = 5V RLOAD = 10k
~ 23 SEC (SOIC, NO SOCKET) ~ 40 SEC (TO -92, NO SOCKET) TO -92
ILOAD = 1mA
75
100 125 150 175 200 225 250 275 300 TIME - sec
TEMPERATURE - C
TPC 20. TMP03 Open-Collector Output Voltage vs. Temperature
TPC 23. Thermal Response Time in Still Air
140 TRANSITION FROM 100 C OIL BATH TO FORCED 25 C AIR 100 SOIC
120
OUTPUT TEMPERATURE - C
TIME CONSTANT - sec
100 80
V+ = 5V RLOAD = 10k
TO -92
V+ = 5V RLOAD = 10k
1.25 SEC (SOIC IN SOCKET) 2 SEC (TO -92 IN SOCKET)
60
TO -92 - WITH SOCKET
40 20
TO -92 - NO SOCKET SOIC - NO SOCKET
TRANSITION FROM STILL 25 C AIR TO STIRRED 100 C OIL BATH
0
25 0 100 200 300 400 500 600 700 AIR VELOCITY - FPM
0
10
20
30 TIME - sec
40
50
60
TPC 21. Thermal Time Constant in Forced Air
TPC 24. Thermal Response Time in Stirred Oil Bath
REV. A
-9-
TMP03/TMP04
APPLICATIONS INFORMATION Supply Bypassing TMP03 Output Configurations
Precision analog products, such as the TMP03, require a wellfiltered 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 switchmode 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 inductance. 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, generous supply bypassing will reduce supply-line induced errors. Local supply bypassing consisting of a 10 F tantalum electrolytic in parallel with a 0.1 F ceramic capacitor is recommended (Figure 4a).
TTL/CMOS LOGIC CIRCUITS +10 F TANT 0.1 F TMP03/ TMP04
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 pullup 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 transistor has a breakdown voltage of 18 V.
V+ DOUT TMP03 TMP04 DOUT
a. b. Figure 5. TMP03 Digital Output Structure
5V POWER SUPPLY
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 capacitance is large, for example when driving a long cable, an external buffer may improve accuracy. See the "Remote Temperature Measurement" section of this data sheet for suggestions.
Interfacing the TMP03 to Low Voltage Logic
Figure 3. Use Separate Traces to Reduce Power Supply Noise
5V 5V 50
V+ 10 F 0.1 F TMP03/ D OUT TMP04 GND 10 F 0.1 F
V+ TMP03/ D OUT TMP04
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.
3.3V 5V
GND
3.3k V+ TMP03 DOUT TO LOW VOLTAGE LOGIC GATE INPUT
a. b. Figure 4. Recommended Supply Bypassing for the TMP03
GND
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).
Figure 6. Interfacing to Low Voltage Logic
Remote Temperature Measurement
When measuring a temperature in situations where high common-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 optoisolator with an integral logic gate output, such as the H11L1 from Quality Technology, can also be used (Figure 8).
-10-
REV. A
TMP03/TMP04
5V 620 VLOGIC V+ OPTO-COUPLER 4.7k
5V
V+
TMP03
DE DI
VCC
B A
DOUT TMP04 NC GND 5V
DOUT GND
ADM485
a.
5V
10k 2N2907 270 V+ TMP03 4.3k VLOGIC OPTO-COUPLER 430
Figure 9. A Differential Line Driver for Remote Temperature Measurement
Microcomputer Interfaces
DOUT GND
b. Figure 7. Optically Isolating the Digital Output
5V 5V 680 V+ TMP03 DOUT GND H11L1
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 requirements 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 microcomputer, 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.
5V
4.7k
Figure 8. An Opto-Isolator with Schmitt Trigger Logic Gate Improves Output Rise and Fall Times
V+ DOUT TMP04 GND INPUT PORT 1.0 OSC 12 TMOD REGISTER TIMER 0 TIMER 1
The TMP03 and TMP04 are superior to analog-output transducers 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 providing additional decoding. As previously mentioned, the digital output of the TMP03 provides excellent noise immunity in remote measurement applications. 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 measurement errors. REV. A
TIMER 0 (16-BITS) 80C51 MICROCOMPUTER TIMER 1 (16-BITS) TCON REGISTER 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.
-11-
TMP03/TMP04
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 measured by Timer 0, and the time that the output is low is measured by Timer 1. When the routine finishes, the results are available in Special Function Registers (SFRs) 08AH through 08DH.
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's 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
-12-
REV. A
TMP03/TMP04
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 produces 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 25C reading ("room temperature"), the nominal error caused by the 2 s delay is only about 0.15C. 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).
5V V+ DOUT TMP04 GND FI (FLAG IN) 16-BIT DOWN COUNTER ADSP-210x CLOCK OSCILLATOR TIMER ENABLE n 10MHz
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 initializing the prescaler and loading the counter with 0FFFFH. 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 0FFFFH 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 temperature of a high power microprocessor. The TMP04 interface would be included as part of the system ASIC, so that the microprocessor 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 resolution 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 generates 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 normal 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 debugging 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.
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 architecture provides very high execution speed. The ADSP-2101 executes one instruction for each clock cycle, versus one instruction 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 prescaler. Loading the value n - 1 into the prescaler register will divide the crystal oscillator frequency by n. For the circuit of
REV. A
-13-
TMP03/TMP04
Listing 2. Software Routine for the TMP04-to-ADSP-210x Interface ;
{ ADSP-21XX Temperature Measurement Routine Altered Registers:
TEMPERAT.DSP
Return value: Computation time:
ax0, ay0, af, ar, si, sr0, my0, mr0, mr1, mr2. ar --> temperature result in 14.2 format 2 * TMP04 output period { Beginning TEMPERAT Program } { Entry point of this subroutine }
} .MODULE/RAM/BOOT=0 TEMPERAT; .ENTRY TEMPMEAS; .CONST PRESCALER=4; .CONST TIMFULSCALE=0Xffff; TEMPMEAS: si=PRESCALER; sr0=TIMFULSCALE; dm(0x3FFB)=si; si=TIMFULSCALE; dm(0x3FFC)=si; dm(0x3FFD)=si; imask=0x01; TEST1: if not fi jump TEST1; TEST0: if fi jump TEST0; ena timer; COUNT2: if not fi jump COUNT2; dis timer; ay0=dm(0x3FFC); ar=sr0-ay0; ax0=ar; dm(0x3FFC)=si; ena timer; COUNT1: if fi jump COUNT1; dis timer; ay0=dm(0x3FFC); ar=sr0-ay0; my0=400; mr=ar*my0(uu); ay0=mr0; ar=mr1; af=pass ar; COMPUTE: astat=0; 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; divq ax0; divq ax0; divq ax0; divq ax0; ax0=0x03AC; ar=ax0-ay0; rts; .ENDMOD;
{ { { { { { {
For timer prescaler } Timer counter full scale } Timer Prescaler set up to 5 } CLKin=10MHz,Timer Period=32.768ms } Timer Counter Register to 65535 } Timer Period Register to 65535 } Unmask Interrupt timer } { Check for FI=1 } { Check for FI=0 to locate transition } { Enable timer, count at a 500ns rate } { Check for FI=1 to stop count } { Save counter=T2 in ALU register }
{ Reload counter at full scale } { Check for FI=0 to stop count } { Save counter=T1 in ALU register }
{ { { { { {
mr=400*T1 } af=MSW of dividend, ay0=LSW } ax0=16-bit divisor } To clear AQ flag } Division 400*T1/T2 } with 0.3 < T1/T2 < 0.7 }
{ { { { {
Result in ay0 } ax0=235*4 } ar=235-400*T1/T2, result in oC } format 14.2 } End of the subprogram }
-14-
REV. A
TMP03/TMP04
T1 DATA (MICROSECONDS) 5V 20 11 1 2 2569
Q1 Q2 Q3 Q4 VCC LE D1 D2 D3 D4
T2 DATA (MICROSECONDS) 12 15 16 19
Q5 Q6 Q7 Q8 OUT GND D5 D6 D7 D8
12 15 16 19
Q5 Q6 Q7 Q8 OUT GND D5 D6 D7 D8
5V 20 11
2569
Q1 Q2 Q3 Q4 VCC LE D1 D2 D3 D4
5V 20 11
2569
Q1 Q2 Q3 Q4 VCC LE D1 D2 D3 D4
12 15 16 19
Q5 Q6 Q7 Q8 OUT GND D5 D6 D7 D8
5V 20 11
2569
Q1 Q2 Q3 Q4 VCC LE D1 D2 D3 D4
12 15 16 19
Q5 Q6 Q7 Q8 OUT GND D5 D6 D7 D8
1 10
1 10
1 10
1 10
74HC373
74HC373
74HC373
74HC373
5V
3
1 2 74HC08 4 5
3
3478
13 14 17 18
3478
13 14 17 18
3478
13 14 17 18
3478
13 14 17 18
6
5V
3 4 5 6 10 11 12 13 14
Q0 Q1 Q2 Q3 EN Q0 Q1 Q2 Q3
5V 16
3 4 5 6 10 11 12 13 14
Q0 Q1 Q2 Q3 EN Q0 Q1 Q2 Q3 VCC EN CLK CLK GND RESET RESET
1MHZ CLOCK
16 V CC 2 EN 1
74HC4520 #1
RESET RESET
2
74HC4520 #2
CLK CLK GND
9
8
7
15
1
9
8
7
15
20pF
1k
5V
20pF 3.9k 5V 15 14 T1 T2 12 A 10 11 Q B 13 9 Q NC CLR GND 8
5V
74HC86 4 6 5 10k 10pF 5V
0.1 F
10 F
T1 T2 4 VCC 16 A 5 Q6 B 3 7 Q CLR NC GND 8 74HC4538
V+ DOUT TMP04 GND
Figure 12. A Hardware Interface for the TMP04
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 temperature sensor is used to measure the temperature of the source
while the TMP03 temperature is monitored by measuring T1 and T2. Once the thermal impedance is determined, the temperature 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 interface schematic). The TMP04 pulse output provides a significant
REV. A
-15-
TMP03/TMP04
advantage in this application because it produces a linear temperature output while needing only one I/O pin and without requiring an A/D converter.
FAST MICROPROCESSOR, DSP, ETC., IN PGA PACKAGE
Thermal Response Time
PGA SOCKET
TMP04 IN SURFACE MOUNT PACKAGE
PC BOARD
Figure 13. Monitoring the Temperature of a High Power Microprocessor Improves System Reliability
The time required for a temperature sensor to settle to a specified 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 capacitance. 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 transferred 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 particular application, and the equivalent power of the heat source. In most applications, the settling time is probably best determined empirically. The TMP03 output operates at a nominal frequency of 35 Hz at 25C, so the minimum settling time resolution is 27 ms.
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
3-Pin TO-92
0.135 (3.43) MIN 0.205 (5.20) 0.175 (4.96)
8-Pin SOIC (SO-8)
0.1968 (5.00) 0.1890 (4.80)
8 5 4
0.210 (5.33) 0.170 (4.38) SEATING PLANE 0.050 (1.27) MAX
0.1574 (4.00) 0.1497 (3.80) PIN 1
1
0.2440 (6.20) 0.2284 (5.80)
0.0500 (1.27) BSC 0.0098 (0.25) 0.0040 (0.10) SEATING PLANE 0.0688 (1.75) 0.0532 (1.35) 0.0192 (0.49) 0.0138 (0.35) 8 0.0098 (0.25) 0 0.0075 (0.19)
0.0196 (0.50) 0.0099 (0.25)
45
0.500 (12.70) MIN
0.019 (0.482) 0.016 (0.407) SQUARE
0.0500 (1.27) 0.0160 (0.41)
8-Pin TSSOP (RU-8)
0.105 (2.66) 0.095 (2.42) 0.105 (2.66) 0.080 (2.42) 0.165 (4.19) 0.125 (3.94) 0.055 (1.39) 0.045 (1.15)
0.122 (3.10) 0.114 (2.90)
8
5
0.105 (2.66) 0.080 (2.42)
1
2
3
0.177 (4.50) 0.169 (4.30) 0.256 (6.50) 0.246 (6.25)
BOTTOM VIEW
PIN 1
1
4
0.0256 (0.65) BSC 0.006 (0.15) 0.002 (0.05) SEATING PLANE 0.0118 (0.30) 0.0075 (0.19)
0.0433 (1.10) MAX 0.0079 (0.20) 0.0035 (0.090)
8 0
0.028 (0.70) 0.020 (0.50)
-16-
REV. A
PRINTED IN U.S.A.
C00334-0-1/02(A)

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