D12320VF25IV Datasheet, PDF (963/1304 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Section 21 Power-Down Modes
Software standby mode is then cleared at the rising edge on the NMI pin.
Oscillator
φ
NMI
NMIEG
SSBY
NMI exception
handling
NMIEG=1
SSBY=1
Software standby mode
(power-down mode)
SLEEP instruction
Oscillation
stabilization
time t_OSC2
NMI exception
handling
Figure 21.2 Software Standby Mode Application Example
21.6.5 Usage Notes
I/O Port Status: 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 Oscillation Stabilization Wait Period: Current dissipation
increases during the oscillation stabilization wait period.
Write Data Buffer Function: The write data buffer function and software standby mode cannot
be used at the same time. When the write data buffer function is used, the WDBE bit in BCRL
should be cleared to 0 to cancel the write data buffer function before entering software standby
mode. Also check that external writes have finished, by reading external addresses, etc., before
executing a SLEEP instruction to enter software standby mode. See section 6.9, Write Data Buffer
Function, for details of the write data buffer function.
Rev.6.00 Sep. 27, 2007 Page 931 of 1268
REJ09B0220-0600