XC908AS60ACFU Motorola Semiconductor Products, XC908AS60ACFU Datasheet - Page 474

• Manufacturer Part Number: XC908AS60ACFU
• Description: MC68HC908AZ60A, MC68HC908AS60A Hcmos Microcontroller Unit Technical Data
• Manufacturer: Motorola Semiconductor Products

Analog-to-Digital Converter (ADC)
26.4.2 Voltage Conversion
26.4.3 Conversion Time
Technical Data
474
NOTE:
NOTE:
ADC will return a logic 0 if the corresponding DDR bit is at logic 0. If the
DDR bit is at logic 1, the value in the port data latch is read.
Do not use ADC channels ATD14 or ATD12 when using the
PTD6/ATD14/TACLK or PTD4/ATD12/TBCLK pins as the clock inputs
for the 16-bit Timers.
When the input voltage to the ADC equals V
Characteristics
scale). If the input voltage equals V
voltages between V
Conversion accuracy of all other input voltages is not guaranteed. Avoid
current injection on unused ADC inputs to prevent potential conversion
error.
Input voltage should not exceed the analog supply voltages.
Conversion starts after a write to the ADSCR (ADC status control
register, $0038), and requires between 16 and 17 ADC clock cycles to
complete. Conversion time in terms of the number of bus cycles is a
function of ADICLK select, CGMXCLK frequency, bus frequency, and
ADIV prescaler bits. For example, with a CGMXCLK frequency of 4
MHz, bus frequency of 8 MHz, and fixed ADC clock frequency of 1 MHz,
one conversion will take between 16 and 17 µs and there will be between
128 bus cycles between each conversion. Sample rate is approximately
60 kHz.
Refer to
Number of Bus Cycles = Conversion Time x Bus Frequency
Conversion Time = 
ADC Characteristics
Analog-to-Digital Converter (ADC)
on page 534), the ADC converts the signal to $FF (full
REFH
and V
16 to 17 ADC Clock Cycles
ADC Clock Frequency
SSA
on page 534.
SSA,
are a straight-line linear conversion.
the ADC converts it to $00. Input
REFH
MC68HC908AZ60A — Rev 2.0
(see
ADC
MOTOROLA