Analog Devices TMP03, TMP04 Datasheet

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a Serial Digital Output Thermometers

TMP03/TMP04*

FEATURES

Low Cost 3-Pin Package Modulated Serial Digital Output

Proportional to Temperature

±1.58C Accuracy (typ) from –258C to +1008C Specified –408C to +1008C, Operation to 1508C

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)

FUNCTIONAL BLOCK DIAGRAM

TMP03/04

TEMPERATURE

SENSOR

VPTAT

DIGITAL

MODULATOR

VREF

 

1

 

2

 

3

 

APPLICATIONS

Isolated Sensors

Environmental Control Systems

Computer Thermal Monitoring

Thermal Protection

Industrial Process Control

Power System Monitors

GENERAL DESCRIPTION

The TMP03/TMP04 is a monolithic temperature detector that generates 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 ±1.5°C (typical) from –25°C to +100°C, 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 –40°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.

DOUT

V+

GND

PACKAGE TYPES AVAILABLE

TO-92

TMP03/04

1

2

3

DOUT V+ GND

BOTTOM VIEW (Not to Scale)

SO-8 and RU-8 (TSSOP)

DOUT

1

8 NC

V+

2

TMP03/04

7

NC

GND

 

TOP VIEW

6

NC

3

NC

 

(Not to Scale)

5

NC

 

4

 

NC = NO CONNECT

(continued on page 4)

*Patent pending.

REV. 0

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.

© Analog Devices, Inc., 1995

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 617/329-4700 Fax: 617/326-8703

TMP03/TMP04–SPECIFICATIONS

TMP03F (V+ = +5 V, –408C TA 1008C unless otherwise noted)

Parameter

Symbol

Conditions

Min Typ

Max

Units

 

 

 

 

 

 

ACCURACY

 

TA = +25°C

1.0

3.0

°C

Temperature Error

 

 

 

–25°C < TA < +100°C1

1.5

4.0

°C

Temperature Linearity

 

–40°C < TA < –25°C1

2.0

5.0

°C

 

1000 Hours at +125°C

0.5

 

°C

Long-Term Stability

 

0.5

 

°C

Nominal Mark-Space Ratio

T1/T2

TA = 0°C

58.8

 

%

Nominal T1 Pulse Width

T1

 

10

 

ms

Power Supply Rejection Ratio

PSRR

Over Rated Supply

0.7

1.2

°C/V

 

 

TA = +25°C

 

 

 

OUTPUTS

 

 

 

 

 

Output Low Voltage

VOL

ISINK = 1.6 mA

 

0.2

V

Output Low Voltage

VOL

ISINK = 5 mA

 

2

V

Output Low Voltage

VOL

0°C < TA < +100°C

 

 

 

ISINK = 4 mA

 

2

V

Digital Output Capacitance

COUT

–40°C < TA < 0°C

 

 

 

(Note 2)

15

 

pF

Fall Time

tHL

See Test Load

150

 

ns

Device Turn-On Time

 

 

20

 

ms

 

 

 

 

 

 

POWER SUPPLY

 

 

 

 

 

Supply Range

V+

 

4.5

7

V

Supply Current

ISY

Unloaded

0.9

1.3

mA

NOTES

1Maximum deviation from output transfer function over specified temperature range. 2Guaranteed but not tested.

Specifications subject to change without notice.

Test Load

10 kΩ to +5 V Supply, 100 pF to Ground

TMP04F (V+ = +5 V, –408C TA +1008C unless otherwise noted)

Parameter

Symbol

Conditions

Min

Typ

Max

Units

 

 

 

 

 

 

 

ACCURACY

 

TA = +25°C

 

 

 

°C

Temperature Error

 

 

1.0

3.0

 

 

–25°C < TA < +100°C1

 

1.5

4.0

°C

Temperature Linearity

 

–40°C < TA < –25°C1

 

2.0

5.0

°C

 

1000 Hours at +125°C

 

0.5

 

°C

Long-Term Stability

 

 

0.5

 

°C

Nominal Mark-Space Ratio

T1/T2

TA = 0°C

 

58.8

 

%

Nominal T1 Pulse Width

T1

 

 

10

 

ms

Power Supply Rejection Ratio

PSRR

Over Rated Supply

 

0.7

1.2

°C/V

 

 

TA = +25°C

 

 

 

 

OUTPUTS

 

IOH = 800 μA

 

 

 

 

Output High Voltage

VOH

V+ –0.4

 

 

V

Output Low Voltage

VOL

IOL = 800 μA

 

 

0.4

V

Digital Output Capacitance

COUT

(Note 2)

 

15

 

pF

Fall Time

tHL

See Test Load

 

200

 

ns

Rise Time

tLH

See Test Load

 

160

 

ns

Device Turn-On Time

 

 

 

20

 

ms

 

 

 

 

 

 

 

POWER SUPPLY

 

 

 

 

 

 

Supply Range

V+

 

4.5

 

7

V

Supply Current

ISY

Unloaded

 

0.9

1.3

mA

NOTES

1Maximum deviation from output transfer function over specified temperature range. 2Guaranteed but not tested.

Specifications subject to change without notice.

Test Load

100 pF to Ground

–2–

REV. 0

Analog Devices TMP03, TMP04 Datasheet

TMP03/TMP04

WAFER TEST LIMITS (V+ = +5 V, GND = 0 V, TA = +258C, unless otherwise noted)

Parameter

Symbol

Conditions

Min Typ

Max

Units

 

 

 

 

 

 

ACCURACY

 

TA = +25°C1

 

 

°C

Temperature Error

 

 

3.0

Power Supply Rejection Ratio

PSRR

Over Rated Supply

 

1.2

°C/V

OUTPUTS

 

IOH = 800 μA

 

 

 

Output High Voltage, TMP04

VOH

V+ – 0.4

 

V

Output Low Voltage, TMP04

VOL

IOL = 800 μA

 

0.4

V

Output Low Voltage, TMP03

VOL

ISINK = 1.6 mA

 

0.2

V

POWER SUPPLY

 

 

 

 

 

Supply Range

V+

 

4.5

7

V

Supply Current

ISY

Unloaded

 

1.3

mA

NOTES

Electrical tests are performed at wafer probe to the limits shown. Due to variations in assembly methods and normal yield loss, yield after packaging is not guaranteed for standard product dice. Consult factory to negotiate specifications based on dice lot qualification through sample lot assembly and testing.

1Maximum deviation from ratiometric output transfer function over specified temperature range.

ABSOLUTE MAXIMUM RATINGS*

DICE CHARACTERISTICS

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 . . . . . . . . . . .

–55°C to +150°C

Dice Junction Temperature . . . . . . . . . . . . . .

. . . . . . +175°C

Storage Temperature Range . . . . . . . . . . . .

–65°C to +160°C

Lead Temperature (Soldering, 60 sec) . . . . . .

. . . . . . +300°C

*CAUTION

1Stresses 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.

2Digital 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.

3Remove power before inserting or removing units from their sockets.

Die Size 0.050 × 0.060 inch, 3,000 sq. mils ( 1.27 × 1.52 mm, 1.93 sq. mm)

Package Type

ΘJA

ΘJC

Units

 

 

 

 

TO-92 (T9)

1621

120

°C/W

SO-8 (S)

1581

43

°C/W

TSSOP (RU)

2401

43

°C/W

NOTE

1ΘJA is specified for device in socket (worst case conditions).

For additional DICE ordering information, refer to databook.

ORDERING GUIDE

 

Accuracy

Temperature

 

Model

at +258C

Range

Package

 

 

 

 

TMP03FT9

±3.0

XIND

TO-92

TMP03FS

±3.0

XIND

SO-8

TMP03FRU

±3.0

XIND

TSSOP-8

TMP03GBC

±3.0

+25°C

Die

TMP04FT9

±3.0

XIND

TO-92

TMP04FS

±3.0

XIND

SO-8

TMP04FRU

±3.0

XIND

TSSOP-8

TMP04GBC

±3.0

+25°C

Die

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/TMP04 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

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–3–

TMP03/TMP04

(continued from page 1)

The TMP03/TMP04 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-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.

 

åD MODULATOR

 

 

INTEGRATOR

 

VOLTAGE REF

COMPARATOR

 

ò

 

&

 

VPTAT

 

 

 

1-BIT

 

 

DAC

 

CLOCK

DIGITAL

TMP03/04

OUT

GENERATOR

FILTER

(SINGLE-BIT)

 

 

Figure 1. TMP03/TMP04 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 avoids major error sources common to other modulation techniques, 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 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/TMP04 avoid this problem and allow the overall circuit to fit into a compact, three-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/TMP04’s clock is irrelevant, and the effects of clock variations are effectively canceled upon decoding by the digital filter.

The output of the TMP03/TMP04 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/TMP04 Output Format

 

æ

400 ´ T1ö

Temperature (°C) =

235 - ç

 

 

÷

T 2

 

 

è

ø

 

æ

720 ´ T1ö

Temperature (°F) =

455 - ç

 

÷

T 2

 

è

ø

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/TMP04 or the user’s counting clock.

–4–

REV. 0

TMP03/TMP04

Table I. Counter Size and Clock Frequency Effects on Quantization Error

Maximum

Maximum

Maximum

Quantization

Quantization

Count Available

Temp Required

Frequency

Error (+258C)

Error (+778F)

 

 

 

 

 

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 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] ´ 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 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 +25°C is calculated from:

Quantization Error (°C) = 400 × ([Count1/Count2] – [Count1 1]/[Count2 + 1])

Quantization Error (°F) = 720 × ([Count1/Count2] – [Count1 1]/[Count2 + 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/TMP04 sets a theoretical minimum resolution of approximately 0.1°C at +25°C.

Self-Heating Effects

The temperature measurement accuracy of the TMP03/TMP04 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/TMP04 package, the mounting technique, and effects of airflow. Static dissipation in the TMP03/TMP04 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 = PDISS × ΘJA = 4.5 mW × 162°C/W = 0.73°C (1.3°F)

For a free-standing surface-mount TSSOP package, the temperature increase due to self-heating would be

T = PDISS × ΘJA = 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 mA continuous (TMP04). Under full load, the output may dissipate

 

æ

T 2

ö

PDISS

= (0.6 V )(0.8 mA)ç

 

÷

 

 

è T1 + T 2

ø

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 × ΘJA = 0.32 mW × 240°C/W = 0.08°C (0.14°F)

This temperature increase adds directly to that from the quiescent dissipation and affects the accuracy of the TMP03/ TMP04 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 × ΘJC = (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 performance can be gained by additional system calibration. To perform a single-point calibration at room temperature, measure the TMP03/TMP04 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 two-point calibration is also possible. This involves measuring the TMP03/TMP04 output at two temperatures, Temp1 and Temp2, and modifying the slope constant (normally 400) as follows:

Slope Constant =

 

 

Temp 2 - Temp1

 

çæ

T1

@ Temp1

÷ö

- çæ

T1

@ Temp 2

÷ö

 

è T 2

@ Temp1ø

è T 2

@ Temp 2 ø

where T1 and T2 are the output high and output low times, respectively.

REV. 0

–5–

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