MC9S08FL16 Series Data Sheet, Rev. 4
System Clock Distribution
Freescale Semiconductor4
2 System Clock Distribution
MC9S08FL16 series use ICS module as clock sources. The ICS module can use internal or external clock
source as reference to provide up to 20 MHz CPU clock. The output of ICS module includes,
• OSCOUT — XOSC output provides external reference clock to ADC.
• ICSFFCLK — ICS fixed frequency clock reference (around 32.768 kHz) provides double of the
fixed lock signal to TPMs and MTIM16.
• ICSOUT — ICS CPU clock provides double of the bus clock which is basic clock reference of
peripherals.
• ICSLCLK — Alternate BDC clock provides debug signal to BDC module.
The TCLK pin is an extra external clock source. When TCLK is enabled, it can provide alternate clock
source to TPMs and MTIM16. The on-chip 1 kHz clock provides clock source of COP module.
Figure 2. System Clock Distribution Diagram
ICS
CPU
÷2
ICSOUT
ICSFFCLK
BUS CLOCK
BDC
TPM2TPM1
ICSLCLK
FIXED CLOCK (XCLK)
1 kHz
ADC
FLASH RAMSCI
XOSC
EXTAL XTAL
OSCOUT
TCLK
COP
IPC
MTIM16
÷2
