MOTOROLA
Chapter 1. Overview
1-7
1.3.3 Nap Mode
Nap mode provides further power savings compared to doze mode. The greater power
savings can be achieved by placing both the processor and the MPC106 in a power
reduction mode. In this mode, only the PCI address decoding, system RAM refresh, and the
processor bus request monitoring are still operating. A hard reset, a PCI bus transaction
referenced to system memory, or a 60x bus request can bring the MPC106 out of the nap
mode. If the MPC106 is awakened by a PCI access, the access is completed, and the
MPC106 returns to the nap mode. If the MPC106 is awakened by a processor access, the
access is completed, but the MPC106 remains in the full-on state. When in the nap mode,
the PLL is required to be running and locked to the system clock (SYSCLK).
1.3.4 Sleep Mode
Sleep mode provides further power savings compared to the nap mode. As in nap mode,
both the processor and the MPC106 are placed in a reduced power mode concurrently. In
sleep mode, no functional units are operating except the system RAM refresh logic, which
can continue (optionally) to perform the refresh cycles. A hard reset or a bus request wakes
the MPC106 from the sleep mode. The PLL and SYSCLK inputs may be disabled by an
external power management controller (PMC). For additional power savings, the PLL can
be disabled by configuring the PLL[0–3] signals into the PLL-bypass mode. The external
PMC must enable the PLL, turn on SYSCLK, and allow the PLL time to lock before
waking the system from sleep mode.
1.3.5 Suspend Mode
Suspend mode is activated by asserting the SUSPEND signal. In suspend mode, the
MPC106 may have its clock input and PLL shut down for additional power savings.
Memory refresh can be accomplished in two ways—either by using self-refresh mode
DRAMs or by using the RTC input. To exit the suspend mode, the system clock must be
turned on in sufficient time to restart the PLL. After this time, SUSPEND may be negated.
In suspend mode, all outputs (except memory refresh) are released to a high-impedance
state and all inputs (including HRST) are ignored.