LPC47N237-MD SMSC [SMSC Corporation], LPC47N237-MD Datasheet - Page 78

• Manufacturer Part Number: LPC47N237-MD
• Description: 3.3V I/O CONTROLLER FOR PORT REPLICATORS AND DOCKING STATIONS
• Manufacturer: SMSC [SMSC Corporation]

Chapter 14 PME Support
Revision 0.3 (10-26-04)
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
register.
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.
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.
DATASHEET
Page 78
3.3v I/O Controller for Port Replicators and Docking Stations
SMSC DS – LPC47N237
The