M306H2FCFP datasheet(39/251 Pages) RENESAS

39 / 251 page

Rev. 1.0

SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

with DATA ACQUISITION CONTROLLER

MITSUBISHI MICROCOMPUTERS

M306H2FCFP

2.5.7 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 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. The fc clock is supplied by the

secondary clock. 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 secondary clock. The only peripheral functions that operate are

those with the sub-clock selected as the count source.

When in single-chip mode, the device can be operated with a low supply voltage (VCC = 3.0 V) only

during low power dissipation mode. Before entering or exiting low power dissipation mode, always

make sure the supply voltage VCC is 5 V.

Note: When operating with a low supply voltage, be aware that only the CPU, ROM, RAM, input/

output ports, timers (timers A and B), and the interrupt control circuit can be used. All other

internal resources (e.g., data slicer, DMAC, A/D, and D/A) cannot be used.

(b) Wait mode

The CPU operation is stopped. The oscillators do not stop.

The main clock and the sub-clock 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.

Figure 2.5.5 is the state transition diagram of the above modes.

M306H2FCFP Datasheet(PDF) 39 Page - Renesas Technology Corp