Datasheet

TMP102
SBOS397C –AUGUST 2007–REVISED OCTOBER 2012 www.ti.com
TEMPERATURE REGISTER indicates Normal mode (EM bit = '0') or Extended
mode (EM bit = '1') and can be used to distinguish
The Temperature Register of the TMP102 is
between the two temperature register data formats.
configured as a 12-bit, read-only register
The unused bits in the Temperature Register always
(Configuration Register EM bit = '0', see the Extended
read '0'.
Mode section), or as a 13-bit, read-only register
(Configuration Register EM bit = '1') that stores the
Table 3. Byte 1 of Temperature Register
(1)
output of the most recent conversion. Two bytes must
D7 D6 D5 D4 D3 D2 D1 D0
be read to obtain data, and are described in Table 3
and Table 4. Note that byte 1 is the most significant
T11 T10 T9 T8 T7 T6 T5 T4
byte, followed by byte 2, the least significant byte.
(T12) (T11) (T10) (T9) (T8) (T7) (T6) (T5)
The first 12 bits (13 bits in Extended mode) are used
(1) Extended mode 13-bit configuration shown in parenthesis.
to indicate temperature. The least significant byte
does not have to be read if that information is not
Table 4. Byte 2 of Temperature Register
(1)
needed. The data format for temperature is
summarized in Table 5 and Table 6. One LSB equals
D7 D6 D5 D4 D3 D2 D1 D0
0.0625°C. Negative numbers are represented in
T3 T2 T1 T0 0 0 0 0
binary twos complement format. Following power-up
(T4) (T3) (T2) (T1) (T0) (0) (0) (1)
or reset, the Temperature Register will read 0°C until
(1) Extended mode 13-bit configuration shown in parenthesis.
the first conversion is complete. Bit D0 of byte 2
Table 5. 12-Bit Temperature Data Format
(1)
TEMPERATURE (°C) DIGITAL OUTPUT (BINARY) HEX
128 0111 1111 1111 7FF
127.9375 0111 1111 1111 7FF
100 0110 0100 0000 640
80 0101 0000 0000 500
75 0100 1011 0000 4B0
50 0011 0010 0000 320
25 0001 1001 0000 190
0.25 0000 0000 0100 004
0 0000 0000 0000 000
–0.25 1111 1111 1100 FFC
–25 1110 0111 0000 E70
–55 1100 1001 0000 C90
(1) The resolution for the Temp ADC in Internal Temperature mode is 0.0625°C/count.
For positive temperatures (for example, +50°C):
Twos complement is not performed on positive numbers. Therefore, simply convert the number to binary
code with the 12-bit, left-justified format, and MSB = 0 to denote a positive sign.
Example: (+50°C)/(0.0625°C/count) = 800 = 320h = 0011 0010 0000
For negative temperatures (for example, –25°C):
Generate the twos complement of a negative number by complementing the absolute value binary number
and adding 1. Denote a negative number with MSB = 1.
Example: (|–25°C|)/(0.0625°C/count) = 400 = 190h = 0001 1001 0000
Twos complement format: 1110 0110 1111 + 1 = 1110 0111 0000
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