
600
Oscillator
NMI
NMIEG
SSBY
NMI
exception
handling
NMIEG = 1
SSBY = 1
SLEEP instruction
Software standby mode
(power-down mode)
Oscillation
stabilization
time (tOSC2)
NMI exception
handling
Figure 17-3 Software Standby Mode Application Example
17.6.5
Usage Notes
I/O Port States: In software standby mode, I/O port states are retained. If the OPE bit is set to 1,
the address bus and bus control signal output is also retained. Therefore, there is no reduction in
current dissipation for the output current when a high-level signal is output.
Current Dissipation During the Oscillation Stabilization Wait Period: Current dissipation
increases during the oscillation stabilization wait period.
17.7
Hardware Standby Mode
17.7.1
Hardware Standby Mode
When the
STBY pin is driven low, a transition is made to hardware standby mode from any mode.
In hardware standby mode, all functions enter the reset state and stop operation, resulting in a
significant reduction in power dissipation. As long as the prescribed voltage is supplied, on-chip
RAM data is retained. I/O ports are set to the high-impedance state.