LPC47N237-MD datasheet(78/138 Pages) SMSC

78 / 138 page

3.3v I/O Controller for Port Replicators and Docking Stations

Revision 0.3 (10-26-04)

Page 78

SMSC DS – LPC47N237

DATASHEET

Chapter 14 PME Support

The LPC47N237 offers support for Power Management Events (PMEs), also referred to as System Control

Interrupt (SCI) events in an ACPI system. A power management event is indicated to the chipset via the

assertion of the nIO_PME signal. In the LPC47N237, the nIO_PME is asserted by active transitions on the

ring indicator inputs nRI pin. The nIO_PME pin can be programmed to be active high or active low via bit 6

in the nIO_PME Output Type and Polarity register (CR39). The nIO_PME pin function defaults to active

low, open-drain output. The output buffer type of the pin can be programmed to be open-drain or push-pull

via bit 7 in the CR39. This pin is powered by VTR. See the Configuration section for description on CR39

Ring Indicate PME functionality is controlled by the RI_PME_Status and RI_PME_EN bits in the PME_STS

and PME_EN registers respectively. These registers are located in the Runtime Registers Block.

The

status bit is set on high-to-low transitions on the nRI pin. If the enable bit is set and if the status bit is set,

the nIO_PME will be active low for Ring Indicate wake event.

The nIO_PME pin can be programmed to be an open drain, active low, driver. The LPC47N237 nIO_PME

pin is fully isolated from other external devices that might pull the nIO_PME signal low; i.e., the nIO_PME

signal is capable of being driven high externally by another active device or pullup even when the

LPC47N237 VCC is grounded, providing VTR power is active.

LPC47N237-MD Datenblatt(PDF) 78 Page - SMSC Corporation