Preliminary W928C73
Publication Release Date: June 2000
- 17 - Revision A1
Power Management
Operation Mode (Normal Mode)
After the power on reset, the W928C73 will enter the normal operation mode. In this mode, all the
system is operable with the main clock.
Idle Mode
While setting the PCON.0 to 1, the system will go to idle mode. In idle mode, the CPU is stopped but
rest of the system and the oscillator is still running as previous state The idle mode can be waked up
by all the interrupt sources.
Power Down Mode
The instruction setting PCON.1 is the last executed prior to going into the Power-down mode. In
Power-down mode the oscillator is stopped. The contents of the on-chip RAM and SFRS are
preserved. The port pins output the values held by their respective SFRs. PSEN are held LOW.
In Power-down mode V
DD
may be reduced to minimize power consumption. However, the supply
voltage must not be reduce until Power-down mode is active, and must be restored before the
hardware reset is applied and frees the oscillator. Reset must be held active until the oscillator has
restarted and stabilized.
The wake-up operation of W928C73 after power-down mode has two approaches, wake-up using
external interrupt INT0, INT1or wake-up using RESET. For INT0 or INT1 wake-up, the controller will
enter the interrupt service routine and is in the slow operation mode and the contents of the on-chip
RAM and SFRS are preserved. For RESET wake-up, the RESET pin has to be kept HIGH for a
minimum of 24 oscillator periods, the uC will enter the power on reset state after wake up.
OPERATION MODE
NORMAL MODE
IDLE
POWER DOWN
Setting Command
Power on reset
Idle mode wake up
3. Power down mode wake up
Set PCON.0 to
1
Set PCON.1 to1
Oscillator
L_clock on
Clock keeps
oscillation
Clock stops
CPU
Operable
Stopped
Stopped
Interrupt
All interrupt operable
INT0, INT1
Watchdog Timer
Operable
Stopped
Timer0, Timer1
L_clock/4 operable
Stopped
RTC
L_clock operable
Stopped
Buzzer Timer
L_clock operable
Stopped
Release Condition
All enabled
interrupts
1. RESET
2. External interrupt
INT0, INT1
Release Time
2
14
main clock