Datasheet

TMP122, TMP124
7
SBOS272B
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READ ADDRESS REGISTER
Figure 7 shows the internal register structure of the
TMP122/TMP124. Table III describes the addresses of the
registers available. The READ address register uses the two
bits to identify which of the data registers should respond to
a read command. Following a complete 16-bit read, the
READ address register is reset to the default power-up state
of P1/P0 equal 0/0.
The user can obtain 9, 10, 11, or 12 bits of resolution by
addressing the Configuration Register and setting the reso-
lution bits accordingly.
For 9-, 10-, or 11-bit resolution, the most
significant bits in the Temperature Register are used with the
unused LSBs set to zero.
CONFIGURATION REGISTER
The Configuration Register is a 16-bit read/write register
used to store bits that control the operational modes of the
temperature sensor. Read/write operations are performed
MSB first. The format of the Configuration Register for the
TMP122/TMP124 is shown in Table VI, followed by a break-
down of the register bits. The power-up/reset value of the
Configuration Register bits R1/R0 equal 1/1, all other bits
equal zero.
TEMPERATURE DIGITAL OUTPUT
(1)
(°C) (BINARY) HEX
150 0100 1011 0000 0111 4B07
125 0011 1110 1000 0111 3E87
25 0000 1100 1000 0111 0C87
0.0625 0000 0000 0000 1111 000F
0 0000 0000 0000 0111 0007
–0.0625 1111 1111 1111 1111 FFFF
–25 1111 0011 1000 0111 F387
–55 1110 0100 1000 0111 E487
NOTE: (1) The last 2 bits are high impedance and are shown as 11 in the table.
TABLE V. Temperature Data Format.
TEMPERATURE REGISTER
The Temperature Register of the TMP122/TMP124 is a 16-
bit, signed read-only register that stores the output of the
most recent conversion. The TMP122/TMP124 are speci-
fied for the temperature range of –40°C to +125°C with
operation from –55°C to +150°C. Up to 16 bits can be read
to obtain data and are described in Table IV. The first 13 bits
are used to indicate temperature where bit D2 is 1, and D1,
D0 are in a high impedance state. Data format for tempera-
ture is summarized in Table V. Following power-up or reset,
the Temperature Register will read 0°C until the first conver-
sion is complete.
SHUTDOWN MODE (SD)
The Shutdown Mode of the TMP122/TMP124 can be used to
shut down all device circuitry except the serial interface.
Shutdown mode occurs when the last 8 bits of the WRITE
command are equal to 1, and will occur once the current
conversion is completed, reducing current consumption to
less than 1µA. To take the part out of shutdown, send any
command or pattern after the 16-bit read with the last 8 bits
not equal to one. Power on default is in active mode.
P1 P0 REGISTER
0 0 Temperature Register (READ Only)
0 1 Configuration Register (READ/WRITE)
10T
LOW
Register (READ/WRITE)
11T
HIGH
Register (READ/WRITE)
TABLE III. Pointer Addresses of the TMP122 and TMP124
Registers.
FIGURE 7. Internal Register Structure of the TMP122 and
TMP124.
D15 D14 D13 D12 D11 D10 D9 D8
0 0 0 0 D1 D0 R1 R0
D7 D6 D5 D4 D3 D2 D1 D0
F1 F0 POL TM1 TM0 0 1 0
TABLE VI. Configuration Register.
I/O
Control
Interface
SCK
SO/I
Temperature
Register
Configuration
Register
T
LOW
Register
T
HIGH
Register
READ Address
Register
CS
D15 D14 D13 D12 D11 D10 D9 D8
T12 T11 T10 T9 T8 T7 T6 T5
D7 D6 D5 D4 D3 D2 D1 D0
T4 T3 T2 T1 T0 1 Z Z
TABLE IV. Temperature Register.