M16C1N Datasheet, PDF (40/238 Pages) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/10 SERIES

M16C/1N Group
6. Clock Generation Circuit
The following describes the clocks generated by the clock generation circuit.
6.1 Main Clock
The main clock is generated by the main clock oscillation circuit. After reset, oscillation starts. The clock
can be stopped using the main clock stop bit (bit 5 at address 000616). Stopping the clock reduces the
power dissipation.
After the oscillation of the main clock oscillation circuit has stabilized, the drive capacity of the XOUT pin
can be reduced using the XIN-XOUT drive capacity select bit (bit 5 at address 000716). Reducing the drive
capacity of the XOUT pin reduces the power dissipation. This bit changes to "1" when shifting from high-
speed/medium-speed mode to stop mode and at a reset. When shifting from low-speed/low power dissi-
pation mode to stop mode, the value before stop mode is retained.
Figure 6.5 shows the examples of main clock connection circuit.
Microcomputer
(Built-in feedback resistor)
XIN
XOUT
(Note 1)
Rd
Microcomputer
(Built-in feedback resistor)
XIN
XOUT
Open
Externally derived clock
CIN
COUT
Vcc
Vss
External ceramic oscillator
External clock input
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.
When the oscillation drive capacity is set to low, check that oscillation is stable. 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.
Figure 6.6 Examples of main clock connection circuit
Rev.1.00 Oct 20, 2004 page 28 of 222
REJ09B0007-0100Z