8.3.1 Temperature Measurement Data

Temperature measurement data are taken over a default range of 0°C to 127°C for both local and remote locations. However, measurements from –55°C to 150°C can be made both locally and remotely by reconfiguring the TMP43x for the extended temperature range, as described in this section. Temperature data resulting from conversions within the default measurement range are 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 Configuration Register 1 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 as low as –64°C, and as high as 191°C; however, most temperature-sensing diodes only measure with the range of –55°C to 150°C.

Additionally, the TMP43x are rated only for ambient local temperatures ranging from –40°C to 125°C. Parameters in Absolute Maximum Ratings must be observed.

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 both the local and remote channels is 0.0625°C, and cannot be adjusted.