MC68HC08AS32 Datasheet, PDF (314/394 Pages) Motorola, Inc – M68HC08 Family of 8-bit microcontroller units (MCUs)

Analog-to-Digital Converter (ADC)
19.6.2 Stop Mode
The ADC module is inactive after the execution of a STOP instruction.
Any pending conversion is aborted. ADC conversions resume when the
MCU exits stop mode. Allow one conversion cycle to stabilize the analog
circuitry before attempting a new ADC conversion after exiting stop
mode.
19.7 I/O Signals
The ADC module has 15 channels that are shared with I/O ports B and
D and one channel with an input-only port bit on port D. Refer to 21.7
ADC Characteristics for voltages referenced in the next three
subsections.
19.7.1 ADC Analog Power Pin (V_DDA/V_DDAREF)/ADC Voltage Reference Pin (V_REFH)
The ADC analog portion uses V_DDA/V_DDAREF as its power pin. Connect
the V_DDA/V_DDAREF pin to the same voltage potential as V_DD. External
filtering may be necessary to ensure clean V_DDA/V_DDAREF for good
results.
NOTE:
V_REFH is the high reference voltage for all analog-to-digital conversions.
Connect the V_REFH pin to a voltage potential between 1.5 volts and
V_DDAREF/V_DDA depending on the desired upper conversion boundary.
Route V_DDA/V_DDAREF carefully for maximum noise immunity and place
bypass capacitors as close as possible to the package.
19.7.2 ADC Analog Ground Pin (V_SSA)/ADC Voltage Reference Low Pin (V_REFL)
The ADC analog portion uses V_SSA as its ground pin. Connect the V_SSA
pin to the same voltage potential as V_SS. V_REFL is the lower reference
supply for the ADC.
Advance Information
314
Analog-to-Digital Converter (ADC)
MC68HC08AS32 — Rev. 3.0
MOTOROLA