Section 5 Power-Down Modes; Overview - Renesas H8 Series Hardware Manual

5.1

Overview

The H8/3644 Group has eight modes of operation after a reset. These include seven power-down
modes, in which power dissipation is significantly reduced. Table 5.1 gives a summary of the eight
operating modes.
Table 5.1 Operating Modes
Operating Mode
Active (high-speed) mode
Active (medium-speed) mode
Subactive mode
Sleep (high-speed) mode
Sleep (medium-speed) mode
Subsleep mode
Watch mode
Standby mode
Note: * Determined by the value set in bits MA1 and MA0 of system control register 1
(SYSCR1).
Of these eight operating modes, all but the active (high-speed) mode are power-down modes. In
this section the two active modes (high-speed and medium speed) will be referred to collectively
as active mode, and the two sleep modes (high-speed and medium speed) will be referred to
collectively as sleep mode.
Figure 5.1 shows the transitions among these operation modes. Table 5.2 indicates the internal
states in each mode.

Section 5 Power-Down Modes

Description
The CPU and all on-chip peripheral functions are operable on
the system clock
The CPU and all on-chip peripheral functions are operable on
the system clock, but at 1/64, 1/32, 1/6, or 1/8 * the speed in
active (high-speed) mode
The CPU, and the time-base function of timer A are operable
on the subclock
The CPU halts. On-chip peripheral functions except PWM are
operable on the system clock
The CPU halts. On-chip peripheral functions except PWM are
operable on the system clock, but at 1/64, 1/32, 1/6, or 1/8 * the
speed in active (high-speed) mode
The CPU halts. The time-base function of timer A are operable
on the subclock
The CPU halts. The time-base function of timer A is operable
on the subclock
The CPU and all on-chip peripheral functions halt
Section 5 Power-Down Modes
Rev. 6.00 Sep 12, 2006 page 87 of 526
REJ09B0326-0600