KSZ8091RNA Datasheet, PDF (24/62 Pages) Micrel Semiconductor – 10Base-T/100Base-TX Physical Layer Transceiver

KSZ8091RNA/RND
3.11.1 TRANSMIT DIRECTION CONTROL (MAC-TO-PHY)
The KSZ8091RNA/RND enters LPI mode for the transmit direction when its attached EEE-compliant RMII MAC de-
asserts TXEN and sets TXD[1:0] to 01. The KSZ8091RNA/RND remains in the LPI transmit state while the RMII MAC
maintains the states of these signals. When the RMII MAC changes any of the TXEN or TX data signals from their LPI
state values, the KSZ8091RNA/RND exits the LPI transmit state.
Figure 3-10 shows the LPI transition for MII (100 Mbps) transmit.
FIGURE 3-10:
LPI TRANSITION - RMII (100 MBPS) TRANSMIT
REF_CLK
TXEN
TXD[1:0] XX XX 00
01
00
01
DATA IDLE
ASSERT LPI
IDLE
WAKE
TIME
PREAMBLE
3.11.2 RECEIVE DIRECTION CONTROL (PHY-TO-MAC)
The KSZ8091RNA/RND 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 KSZ8091RNA/
RND 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 KSZ8091RNA/RND 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 3-11 shows the LPI transition for RMII (100 Mbps) receive.
FIGURE 3-11:
LPI TRANSITION - RMII (100 MBPS) RECEIVE
REF_CLK
CRS_DV
RXD[1:0] XX XX 00
01
00
01
DATA IDLE
ASSERT LPI
IDLE
PREAMBLE
3.11.3 REGISTERS ASSOCIATED WITH EEE
The following registers are provided for EEE configuration and management:
• Standard Register 13h - AFE Control 4 (to enable 10BASE-Te mode)
• MMD address 1h, Register 0h - PMA/PMD Control 1 (to enable LPI)
• MMD address 1h, Register 1h - PMA/PMD Status 1 (for LPI status)
• MMD address 3h, Register 0h - EEE PCS Control 1 (to stop RXC clock for KSZ8091MNX only)
• MMD address 7h, Register 3Ch - EEE Advertisement
• MMD address 7h, Register 3Dh - EEE Link Partner Advertisement
DS00002298A-page 24
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