CN7221 Datasheet, PDF (7/18 Pages) Conexant Systems, Inc – Home Networking Physical Layer Device with Integrated Analog Front End Circuitry

Home Networking PHY with Integrated AFE
TxPKT  HLAN_RX_CLK Active
HLAN_TX_CLK
HLAN_TX_EN
HLAN_TXD
LANfinity™ CN7221
HLAN_RX_CLK
HLAN_CRS
HLAN_RXD
HLAN_COL
HLAN_TX_CLK continues to toggle at 233.3ns until the SFD is observed, as shown in the first section of the above diagram. At
this point, HLAN_TX_CLK is disabled (high) until the AID header has been transmitted on the wire (or until a HLAN_COL has
been detected). This takes about 120us, at which time HLAN_RX_CLK starts toggling, thereby shifting 32 bits of preamble and
SFD back to the MAC. Sometime later, the HLAN_TX_CLK restarts as symbols get sent onto the wire in an analogous manner
as HLAN_RX_CLK during packet reception.
TxPKT  HLAN_TX_EN Cleared
HLAN_TX_CLK
HLAN_TX_EN
HLAN_TXD
HLAN_RX_CLK
HLAN_CRS
HLAN_RXD
HLAN_COL
Once HLAN_TX_EN is cleared, the last symbol gets encoded and transmitted, the looped-back data is presented back to the
MAC, and about 22us later, HLAN_CRS falls. Once HLAN_CRS falls, HLAN_TX_CLK and HLAN_RX_CLK toggle with a period of
233.3ns for 97 clocks, after which the system returns to the Idle state.
LAN-056, Rev. A
Conexant
7
PROPRIETARY INFORMATION