LAN9250 datasheet(45/421 Pages) MICROCHIP

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DS00001913A-page 45

LAN9250

6.3.2

WAKE-UP (PME) NOTIFICATION

A simplified diagram of the logic that controls the PME output pin and PME interrupt can be seen in Figure 6-1.

The PME module handles the latching of the Host MAC Wake On Status (WOL_STS) bit and the PHY Energy-Detect

Status (ED_STS)

bit in the Power Management Control Register (PMT_CTRL).

This module also masks the status bits with the corresponding enable bits (Wake-On-Enable (WOL_EN) and Energy-

Detect Enable (ED_EN)

) and combines the results together to generate the Power Management Interrupt Event

(PME_INT) status bit in the Interrupt Status Register (INT_STS). The PME_INT status bit is then masked with the Power

Management Event Interrupt Enable (PME_INT_EN) bit and combined with the other interrupt sources to drive the IRQ

output pin.

In addition to generating interrupt events, the PME event can also drive the PME output pin to indicate wake-up events

exclusively. The PME event is enabled with the PME Enable (PME_EN) in the Power Management Control Register

(PMT_CTRL), The PME output pin characteristics can be configured via the PME Buffer Type (PME_TYPE), PME Indi-

cation (PME_IND) and PME Polarity (PME_POL) bits of the Power Management Control Register (PMT_CTRL). These

bits allow the PME output pin to be open-drain, active high push-pull or active-low push-pull and configure the output to

be continuous, or pulse for 50 ms.

In system configurations where the PME output pin is shared among multiple devices (wired ORed), the WOL_STS and

ED_STS bits within the PMT_CTRL register can be read to determine which device is driving the PME signal.

When the PM_WAKE bit of the Power Management Control Register (PMT_CTRL) is set, the PME event will automat-

ically wake up the system in certain chip level power modes, as described in Section 6.3.4.2, "Exiting Low Power

Modes," on page 48. This is done independent from the values of the PME_EN, PME_POL, PME_IND and PME_TYPE

Note:

The PME interrupt status bit (PME_INT) in the INT_STS register is set regardless of the setting of

PME_INT_EN.

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