M16C65 Datasheet, PDF (148/829 Pages) Renesas Technology Corp – RENESAS MCU M16C FAMILY / M16C/60

Under development
M16C/65 Group
Preliminary Specification
This is a preliminary specification and is subject to change.
8. Clock Generator
8.3 Clocks Generated by Clock Generators
The clocks generated by the clock generators are described below.
8.3.1 Main Clock
This clock is supplied by the main clock oscillator circuit and used as a clock source for the CPU and
peripheral function clocks. After reset, the main clock is running, but is not used as a clock source for
the CPU.
The main clock oscillator circuit is configured by connecting a resonator between pins XIN and XOUT.
The main clock oscillator circuit contains a feedback resistor, which is separated from the oscillator
circuit in stop mode in order to reduce the amount of power consumed by the chip. The main clock
oscillator circuit may also be configured by feeding an externally generated clock to the XIN pin.
Figure 8.2 shows Main Clock Connection Examples.
MCU
(Built-in feedback resistor)
XIN
Oscillator
XOUT
VSS
Rd ⁽¹⁾
CIN
COUT
MCU
(Built-in feedback resistor)
XIN
External clock
VCC1
VSS
XOUT Open
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 oscillator manufacturer.
When the oscillation drive capacity is set to low, check if oscillation is stable in low status. Also,
place a feedback resistor between XIN and XOUT if the oscillator manufacturer recommends
placing the resistor externally.
Figure 8.2 Main Clock Connection Examples
REJ09B0484-0030 Rev.0.30 Sep 09, 2008
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