TMP451_15 Datasheet, PDF (17/41 Pages) Texas Instruments – TMP451 ±1°C Remote and Local Temperature Sensor With η-Factor and Offset Correction, Series-Resistance Cancellation, and Programmable Digital Filter

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TMP451
SBOS686A – JUNE 2013 – REVISED DECEMBER 2014
7.6.1 Register Information
The TMP451 device contains multiple registers for holding configuration information, temperature measurement
results, and status information. These registers are described in Figure 17 and Table 3.
7.6.1.1 Pointer Register
Figure 17 shows the internal register structure of the TMP451 device. The 8-bit pointer register is used to
address a given data register. The pointer register identifies which of the data registers should respond to a read
or write command on the two-wire bus. This register is set with every write command. A write command must be
issued to set the proper value in the pointer register before executing a read command. Table 3 describes the
pointer register and the internal structure of the TMP451 registers. The power-on reset (POR) value of the
pointer register is 00h (0000 0000b).
Pointer Register
Local and Remote Temperature Registers
Status Register
Configuration Register
Conversion Rate Register
SDA
Local and Remote Temperature Limit Registers
One-Shot Start Register
Remote Temperature Offset Registers
Local and Remote THERM Limit Registers
I/O
Control
Interface
THERM Hysteresis Register
Consecutive ALERT Register
N-factor Correction Register
SCL
Digital Filter Register
Manufacturer ID Register
Figure 17. Internal Register Structure
7.6.1.2 Temperature Registers
The TMP451 device has multiple 8-bit registers that hold temperature measurement results. The eight most
significant bits (MSBs) of the local temperature sensor result are stored in register 00h, while the four least
significant bits (LSBs) are stored in register 15h (the four MSBs of register 15h). The eight MSBs of the remote
temperature sensor result are stored in register 01h, and the four LSBs are stored in register 10h (the four MSBs
of register 10h). The four LSBs of both the local sensor and the remote sensor indicate the temperature value
after the decimal point (for example, if the temperature result is 10.0625˚C, the high byte is 0000 1010 and the
low byte is 0001 0000). These registers are read-only and are updated by the ADC each time a temperature
measurement.
When the full temperature value is needed, reading the MSB value first causes the LSB value to be locked (the
ADC does not write to it) until it is read. The same thing happens upon reading the LSB value first (the MSB
value is locked until it is read). This mechanism assures that both bytes of the read operation are from the same
ADC conversion. This assurance remains valid only until another register is read. For proper operation, read the
high byte of the temperature result first. Read the low byte register in the next read command; if the LSBs are not
needed, the register may be left unread. The power-on reset value of all temperature registers is 00h.
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