82540EP — Networking Silicon
12 Datasheet
3.2.6 Power Management Signals
3.2.7 Impedance Compensation Signals
3.2.8 SMB Signals
3.3 EEPROM and Serial FLASH Interface Signals
Symbol Type Name and Function
LAN_
PWR_
GOOD IPower Good (Power-on Reset). The Power Good signal i s used to indica te that stable
power is available for the 82540EP. When the signa l is low, the 82540EP holds itself in
reset state and f loats all PCI signal s.
PME# OD
Power Management Event. The 82540EP device drives this signal low when it
receives a wake-up event and either the PME Enable bit in the Power Management
Control/Status Register or the Advanced Power Manageme nt Enable (APME) bit of the
Wake-up Control Register (WUC) is 1b.
AUX_PWR I Auxilia ry Power. If the Auxiliary Po wer signal is high, then auxiliary power is available
and the 82540EP devic e should suppor t the D3cold power state.
Symbol Type Name and Function
ZN_COMP I/O
N Device Impedance C ompensation. Thi s signal should be connec t e d t o an exter nal
precision resistor (to VDD) that is in dicative of the PCI t race load. This cel l is used to
dynamically dete rmine the drive st rength required on the N-channel tr ansistors in the
PCI I/O cells.
ZP_COMP I/O
P Device Impedance Compensation. Thi s signal should be connec ted to an external
precision resistor (to VSS) that is indicative of the PCI trace load. This cell is used to
dynamically determin e the drive strength required on the P-channel transistors in the
PCI I/O cells.
Symbol Type Name and Function
SMBCLK I/O SMB Clock. The SMB Clock signal is an open drain signal for serial SMB interface.
SMBDATA I/O SMB Data. The S MB Data signal is a n open drain signal for serial SMB inter face.
SMBALRT# O SMB Alert. The SMB Alert signal is open drain for serial SMB interface .
Symbol Type Name and Function
EE_DI O EEPROM Data Input. The EEPRO M Data Input pin is used for output to the m emory
device.
EE_DO I EEPROM Data Output. The EEPROM Data Output pi n is used for input from the
memory device. The EE_DO includes an internal pull-up resistor.
EE_CS O EEPROM Chip Select. The EEPROM Chip Select signa l is used to enable the device.
EE_SK O EEPROM Serial Clock. The EEPROM Shift Clock provid es the clock rate for the
EEPROM interface, which is approximately 1 MHz.