PXD20RM Datasheet, PDF (1208/1628 Pages) Freescale Semiconductor, Inc – PXD20 Microcontroller

When the MC_PCU receives the mode change request to STANDBY mode it starts the power down phase
for power domain #1. During the power down phase, clocks are disabled and reset is asserted resulting in
a loss of all information for this power domain. Then the power domain is disconnected from the power
supply (power-down state).
new mode
requested by ME
RUN0
STANDBY
Mode set due to reset being asserted to power domain #1
PSTAT.PD1
voltage in
power domain #1
wakeup request
current mode
RUN0
STANDBY
DRUN
power-up state power-down
phase
power-down state
power-up phase
power-up state
Notes:
Not drawn to scale; PCONF1.RUN0 = 1; PCONF1.STBY = 0
Figure 34-7. MC_PCU Events During Power Sequences (STANDBY mode)
When the MC_PCU receives a system wakeup request, it starts the power-up phase. The power domain is
re-connected to the power supply and the voltage in power domain #1 will increase slowly. Once the
voltage is in an operable range, clocks are enabled and the reset is be deasserted (power-up state).
NOTE
It is possible that due to a wakeup request, power-up is requested before a
power domain completed its power-down sequence. In this case, the
information in that power domain is lost.
34.4.4.3 Power Saving for Memories During STANDBY Mode
All memories which are not powered down during STANDBY mode automatically enter a power saving
state. No software configuration is required to enable this power saving state. While a memory is residing
in this state an increased power saving is achieved. Data in the memories is retained.
34.5 Initialization Information
To initialize the MC_PCU, the registers PCU_PCONF2… should be programmed. After programming is
done, those registers should no longer be changed.
34-10
PXD20 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
Freescale Semiconductor