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User’s Manual U12697EJ3V0UM
CHAPTER 24 STANDBY FUNCTION
24.1 Configuration and Function
The
µ
PD784225 has a standby function that can decrease the system’s power consumption. The standby function
has the following six modes.
Table 24-1. Standby Function Modes
HALT mode
Stops the CPU operating clock. The average power consumption can be reduced
by intermittent operation during normal operation.
STOP mode
Stops the main system clock. All of the operations in the chip are stopped, and the
extremely low power consumption state of only a leakage current is entered.
IDLE mode
In this mode, the oscillation circuit continues operating while the rest of the system
stops. Normal program operation can return to power consumption near that of the
STOP mode and for the same time as the HALT mode.
Low power consumption mode
The subsystem clock is used as the system clock, and the main system clock is
stopped. Since reduced power consumption is designed, the CPU can operate with
the subsystem clock.
Low power consumption HALT mode
The CPU operating clock is stopped by the standby function in the low power
consumption mode. Power consumption for the entire system is decreased.
Low power consumption IDLE mode
The oscillation circuit continues operating while the rest of the system is stopped by
the standby function in the low power consumption mode. Power consumption for
the entire system is decreased.
These modes are programmable.
Macro serivce can be started from the HALT mode and the low power consumption HALT mode. After macro service
execution, the device is returned to the HALT mode.
Figure 24-1 shows the standby function state transitions.
