
3850 Group (Spec. H) User’s Manual
APPLICATION
2-97
2.10 Standby function
(2)
Release of stop mode
The stop mode is released by a reset input or by the occurrence of an interrupt request. Note the
differences in the restoration process according to reset input or interrupt request, as described
below.
sRestoration by reset input
The stop mode is released by holding the RESET pin to the “L” input level during the stop mode.
Oscillation is started when all ports are in the input state and the stop mode of the main clock (XIN-
XOUT) is released.
Oscillation is unstable when restarted. For this reason, time for stabilizing of oscillation (oscillation
stabilizing time) (Note) is required. The input of the RESET pin should be held at the “L” level until
oscillation stabilizes.
When the RESET pin is held at the “L” level for 20 cycles or more of XIN after the oscillation has
stabilized, the microcomputer will go to the reset state. After the input level of the RESET pin is
returned to “H”, the reset state is released in approximately 10.5 to 18.5 cycles of the XIN input.
Figure 2.10.2 shows the oscillation stabilizing time at restoration by reset input.
At release of the stop mode by reset input, the internal RAM retains its contents previous to the
reset. However, the previous contents of the CPU register and SFR are not retained.
For more details concerning reset, refer to “2.8 Reset”.
Note: For the setting of oscillation stabilizing time, refer to MISRG (address 003816).
Fig. 2.10.2 Oscillation stabilizing time at restoration by reset input
Vcc
RESET
XIN
Stop mode
Oscillation
stabilizing time
20 cycles or
more of XIN
Operating mode
Time to hold internal reset state =
approximately 10.5 to 18.5 cycles of XIN input
Execute Stop instruction
(Note)
Note: Some cases may occur in which no waveform is input to XIN (in low-speed mode).