The TMP431 has four 8-bit registers that hold temperature measurement results. The TMP432 has six 8-bit registers that hold temperature measurement results. Both the local channel and the remote channel have a high byte register that contains the most significant bits (MSBs) of the temperature analog-to-digital converter (ADC) result and a low byte register that contains the least significant bits (LSBs) of the temperature ADC result. The local channel high byte address for the TMP43x is 00h; the local channel low byte address is 15h for the TMP431 and 29h for the TMP432. The remote channel high byte is at address 01h; the remote channel low byte address is 10h. For the TMP432, the second remote channel high byte address is 23h; the second remote channel low byte is 24h. These registers are read-only and are updated by the ADC each time a temperature measurement is completed.
The TMP43x contain circuitry to assure that a low byte register read command returns data from the same ADC conversion as the immediately preceding high byte read command. This assurance remains valid only until another register is read. For proper operation, the high byte of a temperature register must be read first. The low byte register must be read in the next read command. The low byte register can be left unread if the LSBs are not needed. Alternatively, the temperature registers can be read as a 16-bit register by using a single two-byte read command from address 00h for the local channel result, or from address 01h for the remote channel result (23h for the second remote channel result). The high byte is output first, followed by the low byte. Both bytes of this read operation are from the same ADC conversion. The power-on reset value of both temperature registers is 00h.