mc9s08qd4 Freescale Semiconductor, Inc, mc9s08qd4 Datasheet - Page 98

• Manufacturer Part Number: mc9s08qd4
• Description: Hcs08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Chapter 8 Analog-to-Digital Converter (ADC10V1)
The RTI can be configured to cause a hardware trigger in MCU run, wait, and stop3.
8.1.1.4
The ADC on MC9S08QD4 contains only one analog pin enable register, APCTL1.
8.1.1.5
To use the on-chip temperature sensor, the user must perform the following:
Equation 8-1
Temp = 25°C, using the ADC at f
0.0017 is the uncalibrated voltage versus temperature slope in V/°C. Uncalibrated accuracy of the
temperature sensor is approximately
To improve accuracy the user must calibrate the bandgap voltage reference and temperature sensor.
Calibrating at 25°C will improve accuracy to
Calibration at 3 points, -40°C, 25°C and 105°C will improve accuracy to
been completed, the user will need to calculate the slope for both hot and cold. In application code, the
user would then calculate the temperature using
temperature is above or below 25°C. Once determined if the temperature is above or below 25°C, the user
can recalculate the temperature using the hot or cold slope value obtained during calibration.
8.1.1.6
The ADC is capable of running in stop3 mode but requires LVDSE in SPMSC1 to be set.
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Configure ADC for long sample with a maximum of 1 MHz clock
Convert the bandgap voltage reference channel (AD27)
— By converting the digital value of the bandgap voltage reference channel using the value of
Convert the temperature sensor channel (AD26)
— By using the calculated value of V
V
Characteristics”.
BG
Analog Pin Enables
Temperature Sensor
provides an approximate transfer function of the on-chip temperature sensor for V
Low-Power Mode Operation
the user can determine V
TempC = 25 – ((V
MC9S08QD4 Series MCU Data Sheet, Rev. 3
ADCK
±
12°C, using
= 1.0 MHz and configured for long sample.
DD
. For value of bandgap voltage, see
TEMP
±
DD
4.5°C.
Equation 8-1
, convert the digital value of AD26 into a voltage,
– 1.3894) / ( 0.0033))
Equation
8-1.
as detailed above and then determine if the
±
2.5°C. Once calibration has
Appendix A.5, “DC
Freescale Semiconductor
DD
Eqn. 8-1
= 3.0V,
V
TEMP