C8051T603-GS(2007) 查看數據表（PDF） - Silicon Laboratories
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C8051T603-GS Datasheet PDF : 168 Pages
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C8051T600/1/2/3/4/5
5.5. Temperature Sensor
The temperature sensor transfer function is shown in Figure 5.2. The output voltage (VTEMP) is the ADC
input when the temperature sensor is selected by bits AMX0P2–0 in register AMX0SL. Values for the Off-
set and Slope parameters can be found in Table 5.1.
VTEMP = (Slope x TempC) + Offset
TempC = (VTEMP - Offset) / Slope
Slope (V / deg C)
Offset (V at 0 Celsius)
Temperature
Figure 5.2. Temperature Sensor Transfer Function
5.5.1. Calibration
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, offset and/
or gain calibration is recommended. Typically a 1-point (offset) 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 characteristics, and store this value 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. Parame-
ters that affect ADC measurement, in particular the voltage reference value, will also affect temper-
ature measurement.
A single-point offset measurement of the temperature sensor is performed on each device during produc-
tion test. The measurement is performed at 25 °C ±TBD °C, using the ADC with the internal regulator
selected as the Voltage Reference. The direct ADC result of the measurement is stored in the SFR regis-
ters TOFFH and TOFFL, shown in SFR Definition 5.1 and SFR Definition 5.2.
Rev. 0.5
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