C8051F360 datasheet(49/288 Pages) SILABS

49 / 288 page

Rev. 1.0

C8051F360/1/2/3/4/5/6/7/8/9

5.2.

Temperature Sensor

The typical temperature sensor transfer function is shown in Figure 5.2. The output voltage (VTEMP) is the

positive ADC input when the temperature sensor is selected by bits AMX0P4-0 in register AMX0P.

-50

100

(Celsius)

VTEMP = Slope*(TEMPC) + Offset mV

700

800

900

1000

1100

(mV)

1200

Figure 5.2. Typical Temperature Sensor Transfer Function

The uncalibrated temperature sensor output is extremely linear and suitable for relative temperature mea-

surements (see Table 5.1 for linearity specifications). For absolute temperature measurements, gain and/

or offset calibration is recommended. Typically a 1-point calibration includes the following steps:

Step 1. Control/measure the ambient temperature (this temperature must be known).

Step 2. Power the device, and delay for a few seconds to allow for self-heating.

Step 3. Perform an ADC conversion with the temperature sensor selected as the positive input

and GND selected as the negative input.

Step 4. Calculate the offset and/or gain characteristics, and store these values in non-volatile

memory for use with subsequent temperature sensor measurements.

Figure 5.3 shows the typical temperature sensor error assuming a 1-point calibration at 25 °C. Note that

parameters which affect ADC measurement, in particular the voltage reference value, will also

affect temperature measurement.

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