C8051F52x/F53x
1.4. Operating Modes
The C8051F52x/F52xA/F53x/F53xA devices have four operating modes: Active (Normal), Idle, Suspend,
and Stop. Active mode occurs during normal operation when the oscillator and peripherals are active. Idle
mode halts the CPU while leaving the peripherals and internal clocks active. In Suspend and Stop mode,
the CPU is halted, all interrupts and timers are inactive, and the internal oscillator is stopped. The various
operating modes are described in Table 1.3 below:
Table 1.3. Operating Modes Summary
Active
Idle
Suspend
Stop
Properties
SYSCLK active
CPU active (accessing Flash)
Peripherals active or inactive
depending on user settings
SYSCLK active
CPU inactive (not accessing
Flash)
Peripherals active or inactive
depending on user settings
Internal oscillator inactive
If SYSCLK is derived from the
internal oscillator, the peripherals
and the CIP-51 will be stopped
SYSCLK inactive
CPU inactive (not accessing
Flash)
Digital peripherals inactive;
analog peripherals active or
inactive depending on user
settings
Power
Consumption
Full
Less than Full
Low
Very low
How
Entered?
—
How Exited?
—
IDLE Any enabled interrupt
(PCON.0)
or device reset
SUSPEND Port 0 event match
(OSCICN.5) Port 1 event match
Comparator 0 enabled
and output is logic 0
STOP
(PCON.1)
Device Reset
See Section “8.3. Power Management Modes” on page 89 for Idle and Stop mode details. See Section
“14.1.1. Internal Oscillator Suspend Mode” on page 136 for more information on Suspend mode.
Rev. 1.4
21