The TMP116 has significantly better accuracy than the Class B RTD. In addition, when compared to the Class A RTD, the TMP116 accuracy is better over most of the –55°C to +125°C operating temperature range. This improvement in accuracy is in addition to lower cost and simplified designs when compared with RTDs.
The TMP117 is another semiconductor temperature sensor that can replace RTDs. It is a high-precision digital temperature sensor which provides a 16-bit result with a resolution of 0.0078°C and an accuracy of up to ±0.1°C across the –20°C to +50°C temperature range with no calibration. The TMP117 is I2C- and SMBus™ interface-compatible, has a programmable alert function, and can allow up to four devices on a single bus. Table 2-1 shows the overall accuracy of the TMP117 across its operating range.
|–20°C to +50°C||±0.1°C|
|–40°C to +100°C||±0.2°C|
|–55°C to +150°C||±0.3°C|
Figure 2-2 shows the accuracy of the TMP117 versus an RTD across the operating temperature range of –55°C to +150°C. It is evident looking at Figure 2-2 that the TMP117 with no calibration has the same or better accuracy as an RTD Class-AA sensor. Note that this is the raw accuracy of the two devices and that the final system layout has a minor effect on the TMP117 and a major effect on the accuracy of an RTD sensor due to a number of parameters such as the choice of ADC, layout of signal traces, and component tolerances.
The TMP117 is comparable in accuracy to the Class AA thin-film RTD and consumes a fraction of the power of a PT100 RTD. The systems using the TMP117 require less components, such as delta-sigma ADCs, programmable gain amplifiers, and RC filters, than the systems using RTD elements.