Freescale Semiconductor MPC5604B - Introduction

MPC5604B/C Microcontroller Reference Manual, Rev. 8
Freescale Semiconductor 211
Chapter 10
Power Control Unit (MC_PCU)
10.1 Introduction
10.1.1 Overview
The power control unit (MC_PCU) is used to reduce the overall SoC power consumption. Power can be
saved by disconnecting parts of the SoC from the power supply via a power switching device. The SoC is
grouped into multiple parts having this capability which are called “power domains”.
When a power domain is disconnected from the supply, the power consumption is reduced to zero in that
domain. Any status information of such a power domain is lost. When re-connecting a power domain to
the supply voltage, the domain draws an increased current until the power domain reaches its operational
voltage.
Power domains are controlled on a device mode basis. For each mode, software can configure whether a
power domain is connected to the supply voltage (power-up state) or disconnected (power-down state).
Maximum power saving is reached by entering the STANDBY mode.
On each mode change request, the MC_PCU evaluates the power domain settings in the power domain
configuration registers and initiates a power-down or a power-up sequence for each individual power
domain. The power-up/down sequences are handled by finite state machines to ensure a smooth and safe
transition from one power state to the other.
Exiting the STANDBY mode can only be done via a system wakeup event as all power domains other than
power domain #0 are in the power-down state.
In addition, the MC_PCU acts as a bridge for mapping the VREG peripheral to the MC_PCU address
space.
Figure 10-1 depicts the MC_PCU block diagram.