Datasheet

 2016-2017 Microchip Technology Inc. DS00002112B-page 25
KSZ8795CLX
3.4.5.5 PHY LPI Receive Operation
On receive, entering the LPI mode is triggered by the reception of a sleep signal from the link partner, which indicates
that the link partner is about to enter the LPI mode. After sending the sleep signal, the link partner ceases transmission.
When the receiver detects the sleep signal, the local PHY indicates “Assert LPI” on the MII and the local receiver can
disable some functionality to reduce power consumption. The link partner periodically transmits refresh signals that are
used by the local PHY. This quiet-refresh cycle continues until the link partner initiates transition back to normal mode
by transmitting the wake signal for a predetermined period of time controlled by the LPI assert function. This allows the
local receiver to prepare for normal operation and transition from the “Assert LPI” encoding to the normal inter-frame
encoding on the MII. After a system specified recovery time, the link supports the nominal operational data rate.
3.4.5.6 Negotiation with EEE Capability
The EEE capability shall be advertised during the Auto-Negotiation stage. Auto-Negotiation provides a linked device
with the capability to detect the abilities supported by the device at the other end of the link, determine common abilities,
and configure for joint operation. Auto-Negotiation is performed at power up or reset, on command from management,
due to link failure, or due to user intervention.
During Auto-Negotiation, both link partners indicate their EEE capabilities. EEE is supported only if during Auto-Nego-
tiation both the local device and link partner advertise the EEE capability for the resolved PHY type. If EEE is not sup-
ported, all EEE functionality is disabled and the LPI client does not assert LPI. If EEE is supported by both link partners
for the negotiated PHY type, then the EEE function can be used independently in either direction.
3.4.6 WAKE-ON-LAN (WOL)
Wake-on-LAN (WoL) allows a computer to be turned on or woken up by a network message. The message is usually
sent by a program executed on another computer on the same local area network. Wake-up frame events are used to
wake the system whenever meaningful data is presented to the system over the network. Examples of meaningful data
include the reception of a Magic Packet™, a management request from a remote administrator, or simply network traffic
directly targeted to the local system. The KSZ8795CLX can be programmed to notify the host of the wake-up frame
detection with the assertion of the interrupt signal (INTR_N) or assertion of the power management event signal (PME).
The PME control is by PME indirect registers.
KSZ8795CLX MAC supports the detection of the following wake-up events:
• Detection of energy signal over a pre-configured value: Port PME Control Status Register Bit[0] in PME indirect
registers.
• Detection of a link-up in the network link state: Port PME Control Status Register Bit[1] in the PME indirect regis-
ters.
• Receipt of a Magic Packet: Port PME Control Status Register Bit[2] in the PME indirect registers.
FIGURE 3-6: TRAFFIC ACTIVITY AND EEE LPI OPERATIONS
ACTIVE
LOW POWER
ACTIVE
Tw_PHY
Tw_SYSTEM
QUIET QUIET
QUIET
Ts
Tq Tr
DATA/
IDLE
DATA/
IDLE IDLE
WAKE
REFRESH REFRESH
SLEEP
Ts = THE PERIOD OF TIME THAT THE PHY TRANSMITS THE SLEEP SIGNAL BEFORE TURNING ALL TRANSMITTERS OFF, 200 ≤ Ts ≤ 220 USED IN 100BASE-TX.
Tq = THE PERIOD OF TIME THAT THE PHY REMAINS QUIET BEFORE SENDING THE REFRESH SIGNAL, 20_000 ≤ Tq ≤ 22_000 USED IN 100BASE-TX.
Tr = DURATION OF THE REFRESH SIGNAL, 200 ≤ Tr ≤ 220 USED IN 100BASE-TX.