Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
Revision 1.0 (05-28-09)
16
SMSC LAN8720/LAN8720i
DATASHEET
3.3
Management Signals
3.4
General Signals
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.
Table 3.4 Management Signals 24-QFN
SIGNAL
NAME
24-QFN
PIN #
TYPE
DESCRIPTION
MDIO
12
IOD8
Management Data Input/OUTPUT
: Serial management data input/output.
MDC
13
I8
Management Clock
:
Serial management clock.
Table 3.5 General Signals 24-QFN
SIGNAL
NAME
24-QFN
PIN #
TYPE
DESCRIPTION
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:
LED2 – Link speed LED Indication.
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.
Table 3.3 LED Signals 24-QFN (continued)
SIGNAL
NAME
24-QFN
PIN #
TYPE
DESCRIPTION