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SBOS383A − FEBRUARY 2007
for ambient temperatures ranging from −40°C to +125°C.
Parameters in the Absolute Maximum Ratings table must
be observed.
SERIES RESISTANCE CANCELLATION
Series resistance in an application circuit that typically
results from printed circuit board (PCB) trace resistance
and remote line length (see Figure 11) is automatically
cancelled by the TMP411, preventing what would
otherwise result in a temperature offset.
Table 1. Temperature Data Format
(Local and Remote Temperature High Bytes)
A total of up to 3kΩ of series line resistance is cancelled
by the TMP411, eliminating the need for additional
characterization and temperature offset correction.
LOCAL/REMOTE TEMPERATURE REGISTER
HIGH BYTE VALUE (+1°C RESOLUTION)
STANDARD BINARY
EXTENDED BINARY
TEMP
(°C)
See the two Remote Temperature Error vs Series
Resistance typical characteristics curves for details on the
effect of series resistance and power-supply voltage on
sensed remote temperature error.
BINARY
HEX
00
00
00
00
01
05
0A
19
32
4B
64
7D
7F
7F
7F
7F
BINARY
HEX
00
−64
−50
−25
0
0000 0000
0000 0000
0000 0000
0000 0000
0000 0001
0000 0101
0000 1010
0001 1001
0011 0010
0100 1011
0110 0100
0111 1101
0111 1111
0111 1111
0111 1111
0111 1111
0000 0000
0000 1110
0010 0111
0100 0000
0100 0001
0100 0101
0100 1010
0101 1001
0111 0010
1000 1011
1010 0100
1011 1101
1011 1111
1101 0110
1110 1111
1111 1111
0E
27
DIFFERENTIAL INPUT CAPACITANCE
40
The TMP411 tolerates differential input capacitance of up
to 1000pF with minimal change in temperature error. The
effect of capacitance on sensed remote temperature error
is illustrated in typical characteristic Remote Temperature
Error vs Differential Capacitance.
1
41
5
45
10
4A
59
25
50
72
TEMPERATURE MEASUREMENT DATA
75
8B
A4
BD
BF
D6
EF
FF
Temperature measurement data is taken over a default
range of 0°C to +127°C for both local and remote locations.
Measurements from −55°C to +150°C can be made both
locally and remotely by reconfiguring the TMP411 for the
extended temperature range. To change the TMP411
configuration from the standard to the extended
temperature range, switch bit 2 (RANGE) of the
Configuration Register from low to high.
100
125
127
150
175
191
Temperature data resulting from conversions within the
default measurement range is represented in binary form,
as shown in Table 1, Standard Binary column. Note that
any temperature below 0°C results in a data value of zero
(00h). Likewise, temperatures above +127°C result in a
value of 127 (7Fh). The device can be set to measure over
an extended temperature range by changing bit 2 of the
Configuration Register from low to high. The change in
measurement range and data format from standard binary
to extended binary occurs at the next temperature
conversion. For data captured in the extended
temperature range configuration, an offset of 64 (40h) is
added to the standard binary value, as shown in Table 1,
Extended Binary column. This configuration allows
measurement of temperatures below 0°C. Note that binary
values corresponding to temperatures as low as −64°C,
and as high as +191°C are possible; however, most
temperature sensing diodes only measure with the range
of −55°C to +150°C. Additionally, the TMP411 is rated only
NOTE: Whenever changing between standard and
extended temperature ranges, be aware that the
temperatures stored in the temperature limit registers are
NOT automatically reformatted to correspond to the new
temperature range format. These temperature limit values
must be reprogrammed in the appropriate binary or
extended binary format.
Both local and remote temperature data use two bytes for
data storage. The high byte stores the temperature with
1°C resolution. The second or low byte stores the decimal
fraction value of the temperature and allows a higher
measurement resolution; see Table 2. The measurement
resolution for the remote channel is 0.0625°C, and is not
adjustable. The measurement resolution for the local
channel is adjustable; it can be set for 0.5°C, 0.25°C,
0.125°C, or 0.0625°C by setting the RES1 and RES0 bits
of the Resolution Register; see the Resolution Register
section.
7
BB [ BURR-BROWN CORPORATION ]
