MC9S08DZ16 FREESCALE [Freescale Semiconductor, Inc], MC9S08DZ16 Datasheet - Page 175

• Manufacturer Part Number: MC9S08DZ16
• Description: 8-Bit HCS08 Central Processor Unit (CPU)
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

10.1.5
To use the on-chip temperature sensor, the user must perform the following:
Equation 10-1
where:
For temperature calculations, use the V
In application code, the user reads the temperature sensor channel, calculates V
V
less than V
calibrate the bandgap voltage reference and temperature sensor.
Calibrating at 25°C will improve accuracy to
Calibration at three points, -40°C, 25°C, and 125°C will improve accuracy to ± 2.5°C. Once calibration
has 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.
Freescale Semiconductor
TEMP25
•
•
•
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
— V
— m is the hot or cold voltage versus temperature slope in V/°C.
. If V
TEMP25
V
Characteristics”.
Temperature Sensor
BG
TEMP
TEMP25
TEMP
provides an approximate transfer function of the temperature sensor.
the user can determine V
is the voltage of the temperature sensor channel at the ambient temperature.
the hot slope value is applied in
is greater than V
is the voltage of the temperature sensor channel at 25°C.
Temp = 25 - ((V
MC9S08DZ60 Series Data Sheet, Rev. 4
TEMP25
TEMP25
DD
. For value of bandgap voltage, see
the cold slope value is applied in
±
TEMP
DD
4.5°C.
and m values from the ADC Electricals table.
Equation 10-1
, convert the digital value of AD26 into a voltage,
-V
Equation
TEMP25
) ÷ m)
10-1. To improve accuracy the user should
Chapter 10 Analog-to-Digital Converter (S08ADC12V1)
as detailed above and then determine if the
Equation
TEMP
Section A.6, “DC
, and compares to
10-1. If V
Eqn. 10-1
TEMP
V
TEMP
175
is