Pmc External Power Supply Control - Freescale Semiconductor MPC8313E Family Reference Manual

Powerquicc ii pro integrated processor

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System Configuration

PMC Wake-Up When the MPC8313E is a PCI Host

This sequence assumes the device is a PCI host in D3Warm state. Power is off (0v) on the VDD voltage

supply. The PMC is programed to wake on one of its wake-events: Ethernet magic packet, GPIO, USB,

internal timer, external interrupt, or PCI_PME from an external PCI agent. The PMCCR1[PME_EN] bit

is reset, indicating the device is a host (PCI_PME is an input).

Steps to wake up the device are as follows.

1. A wake-up event occurs and sets the corresponding wake-up event bit in the PMCER[x] register.

This event will trigger an interrupt from the PMC to the IPIC controller if not masked. This

interrupt will not be serviced by the e300 until it wakes up from D3Warm. The PMCER[x] bit

remains set until cleared by e300 software.

2. The wake-up event in the PMCER[x] register triggers the PMC to begin the wake-up process. It

asserts EXT_PWR_CTRL to the external power supply switch. This applies power to the VDD

3. From this point the sequence is similar to the agent power-up sequence described in the previous

section, Step 5 on.

4. Once the e300 boots up and the IPIC has been initialized, the source of the interrupt can be detected

from the PMC registers. The e300 will then reset the source of the wake-up. The source of the

interrupt may be an on-chip device (eTSEC, USB, or GPIO) or an off chip device (agent) that

asserted PCI_PME. An external PCI agent may need to have its power state changed and be

initialized.

5. The e300 clears the on-chip IPIC, PMC interrupts, and wake-up events.

PMC External Power Supply Control

The following diagrams show the assumed scenarios for controlling the power supply to the device. An

external means is required to switch off the VDD supply in low power mode. A commercial power switch

can be used but there is usually a switching delay associated with these devices, sometimes around 1 ms.

A cheaper and faster solution is to use a FET, as shown in

PMCCR2[RCNT] and PMCCR2[PDCNT] timer fields will allow calibration of the device to the switching

characteristics of the power switch.

MPC8313E PowerQUICC II Pro Integrated Processor Family Reference Manual, Rev. 3

5-59. The use of the

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