28.4.8 Temperature sensor
The ADC module includes a temperature sensor whose output is connected to one of the
ADC analog channel inputs. The following equation provides an approximate transfer
function of the temperature sensor.
Figure 28-63. Approximate transfer function of the temperature sensor
where:
• V
TEMP
is the voltage of the temperature sensor channel at the ambient temperature.
• V
TEMP25
is the voltage of the temperature sensor channel at 25 °C.
• m is referred as temperature sensor slope in the device data sheet. It is the hot or cold
voltage versus temperature slope in V/°C.
For temperature calculations, use the V
TEMP25
and temperature sensor slope values from
the ADC Electricals table.
In application code, the user reads the temperature sensor channel, calculates V
TEMP
, and
compares to V
TEMP25
. If V
TEMP
is greater than V
TEMP25
the cold slope value is applied in
the preceding equation. If V
TEMP
is less than V
TEMP25
, the hot slope value is applied in
the preceding equation. ADC Electricals table may only specify one temperature sensor
slope value. In that case, the user could use the same slope for the calculation across the
operational temperature range.
For more information on using the temperature sensor, see the application note titled
Temperature Sensor for the HCS08 Microcontroller Family (document AN3031).
28.4.9 MCU wait mode operation
Wait mode is a lower-power consumption Standby mode from which recovery is fast
because the clock sources remain active. If a conversion is in progress when the MCU
enters Wait mode, it continues until completion. Conversions can be initiated while the
MCU is in Wait mode by means of the hardware trigger or if continuous conversions are
enabled.
Chapter 28 Analog-to-Digital Converter (ADC)
KL25 Sub-Family Reference Manual, Rev. 3, September 2012
Freescale Semiconductor, Inc. 497
To Next Page
Loading...
