
RTL8305SB 
2002/04/09 
7
Rev.1.0
5. Pin Descriptions 
' I ' stands for inputs; 'O' stands for outputs; 'A' stands for analog; 'D' stands for digital  
Upon reset: 
defined as a short time after at the end of a hardware reset. 
After reset: 
defined as the time after the specified 
"Upon Reset" time. 
5.1 Media Connection Pins 
 Pin Name 
RXIP[4:0] 
RXIN[4:0] 
Pin No. Type 
11,12,15, 
16,27,28, 
31,32 
127,128 
  Description 
Differential Receive Data Input:
 Shared by 100Base-TX, 10Base-T 
and 100Base-FX. 
UTP or FX depends on pin GxMode/GyMode/P4Mode[1:0]. 
Note: The 8305SB uses these pins for UTP and Fiber. The 8305S uses 
these pins for UTP only. 
Differential Transmit Data
Output:
 Shared by 100Base-TX, 10Base-T 
and 100Base-FX. 
UTP or FX depends on pin GxMode/GyMode/P4Mode[1:0]. 
Note: The 8305SB uses these pins for UTP and Fiber. The 8305S uses 
these pins for UTP only. 
Default  
AI 
TXOP[4:0] 
TXON[4:0] 
3,4 
7,8 
19,20 
23,24 
35,36 
AO 
5.2 Configuration Pins 
 Pin Name 
ENANEG_BKPRS 
Pin No. Type 
78 
  Description 
Enable Auto-Negotiation Back Pressure: 
This pin sets back pressure 
for auto-negotiation mode for all UTP ports. 
1: Enable 
0: Disable 
8305SB=ENANEG_BKPRS, 8305S=ENBKPRS. This pin has the same 
function for both the RTL8305SB and RTL8305S. The RTL8305SB also 
supports Force mode (through P4ENFC/GxENFC/GyENFC), but this pin 
is used only for Auto-Negotiation mode. The pin name is changed to 
differentiate between “Enable back pressure for Auto-Negotiation mode” 
and “Enable backpressure for Force mode.” 
Disable Broadcast Storm Control: 
1= Disable 
0= Enable 
8305SB=DISBRDCTRL, 8305S=ENBRDCTRL. The RTL8305SB will 
disable this function when pin DISBRDCTRL is left floating. However, the 
RTL8305S will enable this function when pin ENBRDCTRL is left floating. 
LED Blink Time: 
This pin selects the blinking speed of the activity and 
collision LEDs. 
1: On 43ms, then Off 43ms 
0: On 120ms, then Off 120ms 
Enable Reset Blink: 
This pin enables the blinking of the LEDs upon 
reset for diagnosis purposes.
1: Enable reset LED blinking  
0: Disable reset LED blinking 
8305SB=EN_RST_BLNK, 8305S=DIS_RST_BLNK#. This pin has the 
same function for both the RTL8305SB and RTL8305S. The pin name 
has been changed for convenience. 
Default  
1 
I 
DISBRDCTRL 
80 
I 
1 
LED_BLNK_TIME 
89 
I 
1 
EN_RST_BLNK 
90 
I 
1