mc9s08ac32 Freescale Semiconductor, Inc, mc9s08ac32 Datasheet - Page 152

• Manufacturer Part Number: mc9s08ac32
• Description: Hcs08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Chapter 9 Analog-to-Digital Converter (S08ADC10V1)
result of the conversion is transferred to ADCRH and ADCRL upon completion of the conversion
algorithm.
If the bus frequency is less than the f
cannot be guaranteed when short sample is enabled (ADLSMP=0). If the bus frequency is less than 1/11th
of the f
sample is enabled (ADLSMP=1).
The maximum total conversion time for different conditions is summarized in
The maximum total conversion time is determined by the clock source chosen and the divide ratio selected.
The clock source is selectable by the ADICLK bits, and the divide ratio is specified by the ADIV bits. For
example, in 10-bit mode, with the bus clock selected as the input clock source, the input clock divide-by-1
ratio selected, and a bus frequency of 8 MHz, then the conversion time for a single conversion is:
152
ADCK
Single or first continuous 10-bit
Single or first continuous 10-bit
Single or first continuous 10-bit
Single or first continuous 10-bit
Subsequent continuous 10-bit;
Subsequent continuous 10-bit;
Single or first continuous 8-bit
Single or first continuous 8-bit
Single or first continuous 8-bit
Single or first continuous 8-bit
Subsequent continuous 8-bit;
Subsequent continuous 8-bit;
frequency, precise sample time for continuous conversions cannot be guaranteed when long
Conversion Type
Conversion time =
f
f
BUS
BUS
The ADCK frequency must be between f
maximum to meet ADC specifications.
f
f
BUS
BUS
> f
> f
> f
> f
ADCK
ADCK
ADCK
ADCK
Number of bus cycles = 3.5 µs x 8 MHz = 28 cycles
Table 9-11. Total Conversion Time vs. Control Conditions
/11
/11
MC9S08AC60 Series Data Sheet, Rev. 2
ADCK
23 ADCK cyc
8 MHz/1
frequency, precise sample time for continuous conversions
ADICLK
0x, 10
0x, 10
0x, 10
0x, 10
11
11
11
11
xx
xx
xx
xx
NOTE
ADLSMP
+
ADCK
0
0
1
1
0
0
1
1
0
0
1
1
5 bus cyc
minimum and f
8 MHz
20 ADCK cycles + 5 bus clock cycles
23 ADCK cycles + 5 bus clock cycles
40 ADCK cycles + 5 bus clock cycles
43 ADCK cycles + 5 bus clock cycles
5 µs + 20 ADCK + 5 bus clock cycles
5 µs + 23 ADCK + 5 bus clock cycles
5 µs + 40 ADCK + 5 bus clock cycles
5 µs + 43 ADCK + 5 bus clock cycles
Max Total Conversion Time
= 3.5 µs
ADCK
17 ADCK cycles
20 ADCK cycles
37 ADCK cycles
40 ADCK cycles
Table
Freescale Semiconductor
9-11.