C8051F38B-GMR View Datasheet(PDF) - Silicon Laboratories

Part Name

Description

Manufacturer

C8051F38B-GMR

Full Speed USB Flash MCU Family

Silicon Laboratories 

C8051F380/1/2/3/4/5/6/7/C

6.2. Temperature Sensor

The typical temperature sensor transfer function is shown in Figure 6.2. The output voltage (VTEMP) is the

positive ADC input when the temperature sensor is selected by bits AMX0P5-0 in register AMX0P.

(mV)

1200

1100

1000

900

VTEMP = Slope*(TEMPC) + Offset mV

800

700

-50

0

50

100

(Celsius)

Figure 6.2. Typical Temperature Sensor Transfer Function

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

surements (see Table 5.10, “ADC0 Electrical Characteristics,” on page 42 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 6.3 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.

48

Rev. 1.4

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