2017 Microchip Technology Inc. DS00002335B-page 17
KSZ8863MLL/FLL/RLL
During the normal operation mode, the host CPU can set the bit [1:0] in register 195 to transit the current normal oper-
ation mode to any one of the other three power management operation modes.
3.2.2 POWER SAVING MODE
The power saving mode is entered when auto-negotiation mode is enabled, cable is disconnected, and bit [1:0] = 11 in
register 195 is set. When KSZ8863MLL/FLL/RLL is in this mode, all PLL clocks are enabled, MAC is on, all internal reg-
ister values are not changed, and the host interface is ready for CPU read or write. In this mode, it mainly controls the
PHY transceiver on or off based on line status to achieve power saving. The PHY remains transmitting and only turns
off the unused receiver block. Once the activity resumes due to plugging a cable or attempting by the far end to establish
a link, KSZ8863MLL/FLL/RLL can automatically enable the PHY power-up to normal power state from power saving
mode.
During the power saving mode, the host CPU can set bit [1:0] = 0 in register 195 to transit the current power saving
mode to any one of the other three power management operation modes.
3.2.3 ENERGY DETECT MODE
The energy detect mode provides a mechanism to save more power than in the normal operation mode when
KSZ8863MLL/FLL/RLL is not connected to an active link partner. In this mode, the device saves up to 87% of the power.
If the cable is not plugged, KSZ8863MLL/FLL/RLL can automatically enter a low-power state, that is, the energy detect
mode. In this mode, KSZ8863MLL/FLL/RLL keeps transmitting 120 ns width pulses at a rate of 1 pulse/second. Once
the activity resumes due to plugging a cable or attempting by the far end to establish a link, KSZ8863MLL/FLL/RLL can
automatically power up to normal power state in energy detect mode.
Energy detect mode consists of two states: normal power state and low power state. In low power state, KSZ8863MLL/
FLL/RLL reduces the power consumption by disabling all circuitries except the energy detect circuitry of the receiver.
The energy detect mode is entered by setting bit [1:0] = 01 in register 195. When KSZ8863MLL/FLL/RLL is in this mode,
it monitors the cable energy. If there is no energy on the cable for a time longer than the pre-configured value at bit [7:0]
Go-Sleep time in register 196, KSZ8863MLL/FLL/RLL goes into a low power state. When KSZ8863MLL/FLL/RLL is in
low power state, it keeps monitoring the cable energy. Once the energy is detected from the cable, KSZ8863MLL/FLL/
RLL enters the normal power state. When KSZ8863MLL/FLL/RLL is in the normal power state, it can transmit or receive
packet from the cable.
It saves about 87% of the power when the MII interface is in PHY mode (register 53 bit 7 = 0), pin SMTXER3/MII_LINK_3
is connected to High, register 195 bit [1:0] = 01, bit 2 = 1(Disable PLL), and no cables are connected.
3.2.4 SOFT POWER DOWN MODE
The soft power down mode is entered by setting bit [1:0] = 10 in register 195. When KSZ8863MLL/FLL/RLL is in this
mode, all PLL clocks are disabled, PHY and MAC are off, and all internal register values are not changed. When the
host set bit [1:0] = 00 in register 195, this device reverts from current soft power down mode to normal operation mode.
3.2.5 PORT-BASED POWER DOWN MODE
In addition, KSZ8863MLL/FLL/RLL features a per-port power down mode. To save power, a PHY port that is not in use
can be powered down via the port control register 29 or 45 bit 3, or the MIIM PHY register. It saves about 15 mA per port.
3.3 MAC and Switch
3.3.1 ADDRESS LOOKUP
The internal lookup table stores MAC addresses and their associated information. It contains a 1K unicast address table
plus switching information.
KSZ8863MLL/FLL/RLL is guaranteed to learn 1K addresses and distinguishes itself from hash-based lookup tables,
which depending on the operating environment and probabilities, may not guarantee the absolute number of addresses
it can learn.
3.3.2 LEARNING
The internal lookup engine updates its table with a new entry if the following conditions are met:
• The received packet's Source Address (SA) does not exist in the lookup table.
• The received packet is good; the packet has no receiving errors and is of legal length.