
Analog-to-Digital Converter (ADC-15)
Technical Data
MC68HC08AZ32A — Rev 1.0
416
Analog-to-Digital Converter (ADC-15)
For More Information On This Product,
Go to: www.freescale.com
MOTOROLA
23.6.2 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.
23.7 I/O Signals
The ADC module has 15 channels that are shared with I/O ports B and
D. Refer to
Electrical Specifications
on page 423 for voltages
referenced below.
23.7.1 ADC Analog Power Pin (V
DDAREF
)
The ADC analog portion uses V
DDAREF
as its power pin. Connect the
V
DDAREF
pin to the same voltage potential as V
DD
. External filtering may
be necessary to ensure clean V
DDAREF
for good results.
NOTE:
Route V
DDAREF
carefully for maximum noise immunity and place bypass
capacitors as close as possible to the package. V
DDAREF
must be
present for operation of the ADC.
23.7.2 ADC Analog Ground/ADC Voltage Reference Low Pin (A
VSS
/V
REFL
)
The ADC analog portion uses A
VSS
/V
REFL
as its ground pin. Connect the
A
VSS
/V
REFL
pin to the same voltage potential as V
SS
.
V
REFL
is the lower reference supply for the ADC.
23.7.3 ADC Voltage Reference Pin (V
REFH
)
V
REFH
is the high reference voltage for all analog-to-digital conversions.
F
Freescale Semiconductor, Inc.
n
.