
RTL8305SB 
2002/04/09 
10
Rev.1.0
MTXEN/PRXDV 
52 
O 
For MAC mode MII, this pin represents MTXEN, MII transmit enable. 
For PHY mode MII, this pin represents PRXDV, MII received data valid. 
For PHY mode SNI, this pin represents PRXDV, received data valid. 
RTL8305SB = MTXEN/PRXDV, RTL8305S = MTXEN/MRXDV. In 
order to differentiate between MAC and PHY mode, the RTL8305SB 
changes the pin name for PHY mode. 
For MAC mode MII, it is transmit clock, MTXC (acts as input). 
For PHY mode MII/PHY mode SNI, it is receive clock, PRXC (acts as output). 
Because this pin can be connected to a 2.5V or 3.3V device, this pin has 
no internal pull-high resistor. 
RTL8305SB = MTXC/PRXC, RTL8305S = MTXC/MRXC. In order to 
differentiate between MAC and PHY mode, the RTL8305SB changes 
the pin name for PHY mode. 
Select Port 4 operating mode: 
11: UTP / MAC mode MII       10: 100Base-FX mode 
01: PHY mode MII             00: PHY mode SNI 
The RTL8305SB has 4 options and the RTL8305S has 3 options. 
Port4 Link Status for MAC: 
When the PHY part of Port4 is not used, 
this pin determines the link status of the Port4 MAC in real-time. That is 
link status of real-time for MII MAC/MII PHY/SNI PHY only. This pin 
is low active. 
1: No Link. 
0: Link 
When P4MODE[1:0]=11 (UTP/MAC mode MII), this pin determines 
the link status of MAC mode MII only in real time. The link status of 
UTP mode is provided by the internal PHY in real time. If both UTP and 
MII port are linked OK, UTP has higher priority. 
When P4MODE[1:0]=10 (100Base-FX mode), this pin does nothing. 
The internal PHY will provide the link status to the MAC in real time. 
When P4MODE[1:0]=01 (PHY mode MII), this pin determines the link 
status of Port4 in real time. 
When P4MODE[1:0]=00 (PHY mode SNI), this pin determines the link 
status of Port4 in real time. 
This pin should be left floating in UTP or FX mode, and pulled down in 
the other three modes. 
In MAC mode MII/ PHY mode MII/ PHY mode SNI, configuration of 
this pin will not set the link status of the internal register. The link status 
depends on the external PHY or MAC. 
1 
MTXC/PRXC 
51 
I/O 
P4MODE[1:0] 
97,98 
I 
11 
P4LNKSTA# 
49 
I 
1 
Cont…