43.6.1 Principle of Operation

The TSENS accurately measures the operating temperature of the device by comparing the difference in two temperature dependent frequencies to a known frequency. The frequency of the temperature dependent oscillator (TOSC) is measured twice: first with the min configuration and next with the max configuration. The number of periods of GCLK_TSENS used for the measurement is defined by the GAIN register. The width of the resulting pulse is measured using a counter clocked by GCLK_TSENS in the up direction for the 1st phase and in the down 2nd phase.

The resulting signed value is proportional to the temperature and is corrected for offset by the contents of the OFFSET register.

VALUE = OFFSET + GAIN \times (\frac{f_{TOSCMIN}}{f_{GCLK}} + - \frac{f_{TOSCMAX}}{f_{GCLK}})

Note:

The values of GAIN and OFFSET are factory programmed to give a specific temperature slope when using the undivided internal 48MHz oscillator (OSC48M) as the GCLK_TSENS source. Other frequencies/sources may be used, but the GAIN setting and/or expected slope will need to be scaled accordingly.
The calibration value should be copied and written into the GAIN and OFFSET registers to get the specified accuracy.