M16C26 Datasheet, PDF (47/239 Pages) Renesas Technology Corp – 16-BIT CMOS SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/20 SERIES

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Preliminary Specifications Rev. 0.9
Specifications in this manual are tentative
Power Control
and
subject to change.
SINGLE-CHIP 16-BIT
M16C/26 Group
CMOS MICROCOMPUTER
Power control
The following is a description of the three available power control modes:
Modes
Power control is available in three modes.
(a) Normal operation mode
• High-speed mode
Divide-by-1 frequency of the main clock becomes the BCLK. The CPU operates with the BCLK.
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 with the BCLK. Each peripheral function operates according to its assigned clock.
• Low-speed mode
fC becomes the BCLK. The CPU operates according to the fC clock. The fC clock is supplied by the
subclock. Each peripheral function operates according to its assigned clock.
• Low power dissipation 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 subclock. The only peripheral functions that operate are
those with the subclock selected as the count source.
• Ring oscillator mode
The ring oscillator clock divided by 1 (undivided), 2, 4, 8, or 16 provides BCLK. The ring oscillator
clock is also the clock source for the peripheral function clocks. If the sub-clock is on, fC32 can be
used as the count source for timers A and B.
• Ring oscillator low power dissipation mode
The main clock is turned off after being placed in ring oscillator mode. The CPU clock can be selected as
in the ring oscillator mode. The ring oscillator clock is the clock source for the peripheral function clocks.
If the sub-clock is on, fC32 can be used as the count source for timers A and B. When the operation
mode is returned to the high and medium speed modes, set the CM06 bit to “1” (divided by 8 mode).
(b) Wait mode
The CPU operation is stopped. The oscillators do not stop.
(c) 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 decreasing power consumption.
Table 1.8.4. Oscillation state in each mode
XIN
XCIN
Ring
Medium-speed mode (divide-by-8
frequency after reset released)
BCLK
OFF
OFF
High/medium-speed
BCLK ON/OFF ON/OFF
Low-speed mode
ON
BCLK OFF
Low power dissipation mode
OFF BCLK OFF
Ring oscillator mode
Ring oscillator low power
dissipation mode
ON/OFF ON/OFF BCLK
OFF ON/OFF BCLK
Figure 1.8.8 is the state transition diagram of the above modes.
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Renesas Technology Corp.