KSZ8091MNX Datasheet, PDF (40/83 Pages) Micrel Semiconductor – 10Base-T/100Base-TX Physical Layer Transceiver

Micrel, Inc.
KSZ8091MNX/KSZ8091RNB
Receive Direction Control (PHY-to-MAC)
The KSZ8091MNX enters LPI mode for the receive direction when it receives the /P/ code bit pattern (Sleep/Refresh)
from its EEE-compliant link partner. It then de-asserts RXDV, asserts RXER, and drives RXD[3:0] to 0001. The
KSZ8091MNX remains in the LPI receive state while it continues to receive the refresh from its link partner, so it will
continue to maintain and drive the LPI output states for the MII receive signals to inform the attached EEE-compliant MII
MAC that it is in the LPI receive state. When the KSZ8091MNX receives a non /P/ code bit pattern (non-refresh), it exits
the LPI receive state and sets the RXDV, RXER, and RX data signals to set a normal frame or normal idle.
The KSZ8091MNX stops the RXC clock output to the MAC after nine or more RXC clock cycles have occurred in the LPI
receive state, to save more power. By default, RXC clock stoppage is enabled. It is disabled by writing a ‘0’ to MMD
address 3h, Register 0h, Bit [10].
Figure 13 shows the LPI transition for MII (100Mbps) receive.
Figure 13. LPI Transition – MII (100Mbps) Receive
Similarly, the KSZ8091RNB enters LPI mode for the receive direction when it receives the /P/ code bit pattern
(Sleep/Refresh) from its EEE-compliant link partner. It then de-asserts CRS_DV and drives RXD[1:0] to 01. The
KSZ8091RNB remains in the LPI receive state while it continues to receive the refresh from its link partner, so it will
continue to maintain and drive the LPI output states for the RMII receive signals to inform the attached EEE-compliant
RMII MAC that it is in the LPI receive state. When the KSZ8091RNB receives a non /P/ code bit pattern (non-refresh), it
exits the LPI receive state and sets the CRS_DV and RX data signals to set a normal frame or normal idle.
Figure 14 shows the LPI transition for RMII (100Mbps) receive.
August 31, 2015
Figure 14. LPI Transition – RMII (100Mbps) Receive
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Revision 1.2