M16C6S_09 Datasheet, PDF (33/208 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

M16C/6S Group
Clock Generation Circuit
The following describes the clocks generated by the clock generation circuit.
(1) Main Clock
Main clock is supplied by IT800 with a tripled clock of XIN (main clock oscillator).
This clock is used as the clock source for the CPU and peripheral function clocks. The main clock oscilla-
tor circuit is configured by connecting a resonator between the XIN and XOUT pins. The main clock oscil-
lator circuit contains a feedback resistor. The main clock oscillator circuit may also be configured by
feeding an externally generated clock to the XIN pin. Figure 1.7.6 shows the examples of main clock
connection circuit.
After reset, the main clock divided by 8 is selected for the CPU clock.
Even if XIN input stops, main clock oscillator does not stop.
During stop mode, all clocks of internal M16C core including the main clock are turned off. Refer to
“power control”.
Microcomputer
(Built-in feedback resistor)
XIN
XOUT
(Note 2)
(Note 1)
Rd
CIN
COUT
Microcomputer
(Built-in feedback resistor)
XIN
XOUT
Open
Externally derived clock
Vcc
Vss
Note 1: Insert a damping resistor if required. The resistance will vary depending on the oscillator and the oscillation drive
capacity setting. Use the value recommended by the maker of the oscillator.
Also, if the oscillator manufacturer's data sheet specifies that a feedback resistor be added external to the chip,
insert a feedback resistor between XIN and XOUT following the instruction.
Note 2: Operating frequency must be 5.12 MHz, overall accuracy must be less than 150 ppm.
Figure 1.7.6. Examples of Main Clock Connection Circuit
Rev.5.01 Dec 10, 2009 page 33 of 201
REJ03B0014-0501