M16C Datasheet, PDF (46/262 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

Preliminary Specifications REV.B
Mitsubishi microcomputers
Specifications in this manual are tentative and subject to change.
M16C / 6N Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Power Control
Power Control
The following is a description of the three available power control modes:
Modes
Power control is available in three modes.
(1) Normal operation mode
• High-speed mode
Divide-by 1 frequency of the main clock becomes the BCLK. The CPU operates with the internal
clock selected. Each peripheral function operates according to its assigned clock.
• Medium-speed mode
Divide-by-2, divide by-4 divide-by-8 or divide-by-16 frequency of the main clock becomes the BCLK.
The CPU operates according to the internal clock selected. Each peripheral function operates
according to its assigned clock.
• Low-speed mode
fc becomes the BCLK. The CPU operates according to the fc clock selected. The fc clock is
supplied by the secondary clock. Each peripheral function operates according to its assigned clock.
• Low power consumption mode
The main clock operating in low-speed mode is stopped. The CPU operates according to the fc
clock. The fc clock is supplied by the secondary clock. The only peripheral functions that operate
are those with the sub-clock selected as the count source.
• Ring oscillator mode
The ring oscillator replaces X_IN. No-division-, divide-by-2-, 4-, 8- or 16 mode can be selected by
changing the values in CM06, CM16 and CM17. The higher the division ratio is, the lower power
consumption. The clock driver of X_IN can be stopped by changing the value of the main clock stop bit
to "0" when the CPU operates using the ring oscillator. Through this the power consumption will be
still lower.
(2) Wait mode
The CPU operation is stopped. The oscillator does not stop.
(3) Stop mode
All oscillators stop. The CPU and all built-in peripheral functions stop. This mode, among the three
modes listed here, is the most effective in reducing power consumption.
Figure 5-7 shows the state transition of power control modes.
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