SMSC LAN8720i User Manual

Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support

Revision 1.0 (05-28-09)

16

SMSC LAN8720/LAN8720i

LED2/

nINTSEL

2

IOPU

LED2 – Link speed LED Indication.
See 

 for a description of LED modes.

nINTSEL: On power-up or external reset, the mode of the nINT/REFCLKO 
pin is selected. 
See 

 for additional detail.

„

When LED2/nINTSEL is floated or pulled to VDD2A, nINT is selected for 
operation on pin nINT/REFCLKO (default).

„

When LED2/nINTSEL is pulled low to VSS through a resistor, REFCLKO is 
selected for operation on pin nINT/REFCLKO.

MDIO

12

IOD8

Management Data Input/OUTPUT: Serial management data input/output. 

MDC

13

I8

Management Clock: Serial management clock. 

nINT/

REFCLKO

14

IOPU

nINT – Active low interrupt output. Place an external resistor pull-up to 
VDDIO.

REFCLKO – 50MHz clock derived from the 25MHz crystal oscillator.
See 

 for additional detail.

„

See DESCRIPTION of pin 2: 

„

This signal is mux’d with REFCLKO.

XTAL1/

CLKIN

5

ICLK

Clock Input: Crystal connection or external clock input. 

XTAL2

4

OCL

K

Clock Output: Crystal connection.

„

Float this pin when an external clock is driven to XTAL1/CLKIN.

nRST

15

IOPU

External Reset: Input of the system reset. This signal is active LOW.