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Clocks and Power Control
5-18
MPC801 USER’S MANUAL
MOTOROLA
5
Table 5-5 describes all possible transfers between low-power modes. The MPC801 enters
a low-power mode by setting the LPM bits appropriately. This can only be done in one of the
normal modes and not in the doze mode. Exiting from low-power modes occurs through an
asynchronous or synchronous interrupt. An enabled asynchronous interrupt clears the LPM
bits, but does not change the PLPRCR
CSRC
bit. The asynchronous interrupt is responsible
for exiting from normal, low doze high, low, and sleep modes to normal high mode. The
asynchronous interrupt sources are:
Asynchronous wake-up interrupt from the interrupt controller
Real-time clock, periodic interrupt timer, timebase, or decrementer interrupts (if
enabled)
Table 5-5. MPC801 Low-Power Modes
OPERATION
MODE
SPLL
CLOCKS
WAKE-UP
METHOD
RETURN TIME FROM WAKE-UP
EVENT TO NORMAL HIGH
MPC801 POWER
CONSUMPTION
AT 50MHZ
FUNCTIONALITY
Normal High
LPM=00
Active
Full
Freq. div
2
DFNH
—
—
×
20 mWatt+
1/2
DFNH
Watt
Full Functions Not In
Use Are Shut Off
Normal Low
(“Gear”)
LPM=00
Active
Full
Freq. div
2
DFNL+1
Software
or
Interrupt
Asynchronous Interrupts:
3-4 Maximum System Cycles
Synchronous Interrupts:
3-4 Actual System Cycles
×
20 mWatt+
1/2
(DFNL+1)
Watt
Doze High
LPM=01
Active
Full
Freq. div
2
DFNH
Interrupt
×
20mWatt+
0.4/2
DFNH
Watt
Enabled: RTC, PIT,
and MEMC,
Disabled: Extended
Core
Doze Low
LPM=01
Active
Full
Freq. div
2
DFNL+1
Interrupt
×
20 mWatt+
0.4/2
(DFNL+1)
Watt
Sleep
LPM=10
Active
Not
Active
Interrupt
3-4 Maximum System clocks
<10 mW
Enabled: RTC, PIT,
TB, and DEC
Deep Sleep
LPM=11
TEXPS=1
Not
Active
Not
Active
Interrupt
<500 Oscillator Cycles
16 msec-32 KHz
125
μ
sec-4 MHz
TBD
Power-Down
LPM=11
TEXPS=0
Not
Active
Not
Active
Interrupt
<500 Oscillator Cycles + Power
Supply Wake-Up
(PwSp_Wake+ 16 msec) @ 32 KHz
32 KHz- ~10
μ
A,
KAPWR = 3.0 V
Temperature=50
°
C