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 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
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
1.5C
(typical) from 25
C to +100C, 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 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.
(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
25
C < T
A
< +100
C
1
1.5
4.0
C
40
C < T
A
< 25
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
40
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
25
C < T
A
< +100
C
1
1.5
4.0
C
40
C < T
A
< 25
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+ 0.4
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/TMP04SPECIFICATIONS
TMP03F
(V+ = 5 V, 40 C
T
A
100 C, unless otherwise noted.)
2
(V+ = 5 V, 40 C
T
A
100 C, unless otherwise noted.)
TMP03/TMP04
REV. A
3
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 . . . . . . . . . . 55
C to +150C
Dice Junction Temperature . . . . . . . . . . . . . . . . . . . . . . 175
C
Storage Temperature Range . . . . . . . . . . . . 65
C to +160C
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
4
(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 "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.
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's 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 25C. The output format is
readily decoded by the user as follows:
T1
T2
Figure 2. TMP03 Output Format
Temperature (
C) =
235
-
400
T1
T 2
Temperature (
F) =
455
-
720
T1
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
5
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 ([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 25C 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 25C.
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
162C/W = 0.73C (1.3F)
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
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
P
DISS
= 0.6 V
(
)
0.8 mA
(
)
T 2
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 = P
DISS
JA
= 0.32 mW
240C/W = 0.08C (0.14F)
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)
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 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
- Temp1
T1 @ Temp1
T 2 @ Temp1
-
T1 @ Temp 2
T 2 @ Temp 2
where T1 and T2 are the output high and output low times,
respectively.
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