Datasheet

Section 6 Power-Down Modes
Rev. 3.00 Mar. 15, 2006 Page 84 of 526
REJ09B0060-0300
6.2.1 Sleep Mode
In sleep mode, CPU operation is halted but the on-chip peripheral modules function at the clock
frequency set by the MA2, MA1, and MA0 bits in SYSCR2. CPU register contents are retained.
When an interrupt is requested, sleep mode is cleared and interrupt exception handling starts.
Sleep mode is not cleared if the I bit of the condition code register (CCR) is set to 1 or the
requested interrupt is disabled in the interrupt enable register. After sleep mode is cleared, a
transition is made to active mode when the LSON bit in SYSCR2 is 0, and a transition is made to
subactive mode when the bit is 1. When the RES pin goes low, the CPU goes into the reset state
and sleep mode is cleared.
6.2.2 Standby Mode
In standby mode, the clock pulse generator stops, so the CPU and on-chip peripheral modules stop
functioning. However, as long as the rated voltage is supplied, the contents of CPU registers, on-
chip RAM, and some on-chip peripheral module registers are retained. On-chip RAM contents
will be retained as long as the voltage set by the RAM data retention voltage is provided. The I/O
ports go to the high-impedance state.
Standby mode is cleared by an interrupt. When an interrupt is requested, the system clock pulse
generator starts. After the time set in bits STS2 to STS0 in SYSCR1 has elapsed, and interrupt
exception handling starts. Standby mode is not cleared if the I bit of CCR is set to 1 or the
requested interrupt is disabled in the interrupt enable register.
When the RES pin goes low, the system clock pulse generator starts. Since system clock signals
are supplied to the entire chip as soon as the system clock pulse generator starts functioning, the
RES pin must be kept low until the pulse generator output stabilizes. After the pulse generator
output has stabilized, the CPU starts reset exception handling if the RES pin is driven high.