A common system requirement is the ability to multi-source components on a BOM. This section provides a method for multi-sourcing with the TMP6 and an NTC thermistors. The key adjective here is to determine which device is onboard based on its initial change in voltage (∆V ) to use the correct temperature conversion code from then on.

The first step is to pre-determine the direction of the initial change in temperature (∆T) during start-up. During assembly, the board can heat up by about 5°C on its own due to self heating of power supplies, the processor, etc. If you'd like, you can induce a greater change in temperature by using a heat lamp (+∆T) or freeze spray (-∆T ).

The second step is to have your software determine if the initial change in voltage (∆V ) during start-up is positive (+) or negative (-). Using the table below as a reference, your software can determine which thermistor type is onboard and use the correct temperature conversion code.

Figure 6-4 Dual Sourcing for TMP6 and NTC Thermistors.