VSC8601 Datasheet
Functional Descriptions
Figure 5.
Cat5 Media Interface
SimpliPHY
TXVP_A_n
Transformer
0.1 µF
0.1 µF
0.1 µF
RJ-45
TXVN_A_n
TXVP_B_n
1
2
A+
A-
3
B+
6
B-
TXVN_B_n
TXVP_C_n
4
C+
5
C-
TXVN_C_n
TXVP_D_n
7
D+
8
D-
0.1 µF
TXVN_D_n
75
75
1000pF, 2kV
75
75
3.4
Cat5 Auto-Negotiation
The VSC8601 device supports twisted pair auto-negotiation as defined by clause 28 of
the IEEE standard 802.3-2000.
The auto-negotiation process consists of the evaluation of the advertised capabilities of
the PHY and its link partner to determine the best possible operating mode, throughput
speed, duplex configuration, and master or slave operating modes in the case of
1000BASE-T setups. Auto-negotiation also allows a connected MAC to communicate
with its link partner MAC through the VSC8601 device using the optional “next pages,”
which set attributes that may not otherwise be defined by the IEEE standard.
In installations where the Cat5 link partner does not support auto-negotiation, the
VSC8601 automatically switches to use parallel detection to select the appropriate link
speed.
Clearing VSC8601 device register 0, bit 12 disables clause 28 twisted-pair
auto-negotiation. If auto-negotiation is disabled, the state of register bits 0.6, 0.13,
Revision 4.1
September 2009
Page 19
VITESSE [ VITESSE SEMICONDUCTOR CORPORATION ]
