VSC8512XJG-02

The VSC8512-02 supports twisted pair autonegotiation, as defined by IEEE 802.3-2008 Clause 28 and
IEEE 802.3az. The autonegotiation process evaluates the advertised capabilities of the local PHY and its
link partner to determine the best possible operating mode. In particular, autonegotiation can determine
speed, duplex configuration, and master or slave operating modes for 1000BASE-TX. Autonegotiation
also enables a connected MAC to communicate with its link partner MAC through the VSC8512-02 using
optional next pages, which set attributes that may not otherwise be defined by the IEEE standard.
If the Cat5 link partner does not support autonegotiation, the VSC8512-02 automatically uses parallel
detection to select the appropriate link speed.
Autonegotiation is disabled by clearing register 0, bit 12. If autonegotiation is disabled, the state of
register bits 0.6, 0.13, and 0.8 determine the device operating speed and duplex mode. Note that while
10BASE-T and 100BASE-T do not require autonegotiation, Clause 40 has defined 1000BASE-T to
require autonegotiation.