Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
Chapter 3 Pin Description
This chapter describes the signals on each pin. When a lower case “n” is used at the beginning of the
signal name, it indicates that the signal is active low. For example, nRST indicates that the reset signal
is active low. The buffer type for each signal is indicated in the TYPE column, and a description of the
buffer types is provided in Table 3.1.
Table 3.1 Buffer Types
BUFFER TYPE
DESCRIPTION
I8
Input.
O8
Output with 8mA sink and 8mA source.
Input/Open-drain output with 8mA sink.
Input with 67k (typical) internal pull-up.
IOD8
IPU
Note 3.1
IPD
Input with 67k (typical) internal pull-down.
Note 3.1
IOPU
Note 3.1
Input/Output with 67k (typical) internal pull-up. Output has 8mA sink and 8mA source.
Input/Output with 67k (typical) internal pull-down. Output has 8mA sink and 8mA source.
IOPD
Note 3.1
AI
AIO
ICLK
OCLK
P
Analog input
Analog bi-directional
Crystal oscillator input pin
Crystal oscillator output pin
Power pin
Note 3.1 Unless otherwise noted in the pin description, internal pull-up and pull-down resistors are
always enabled. The internal pull-up and pull-down resistors prevent unconnected inputs
from floating, and must not be relied upon to drive signals external to LAN8720/LAN8720i.
When connected to a load that must be pulled high or low, an external resistor must be
added.
Note: The digital signals are not 5V tolerant.They are variable voltage from +1.6V to +3.6V, as shown
in Table 7.1.
Revision 1.0 (05-28-09)
SMSC LAN8720/LAN8720i
DATA1S4HEET
SMSC [ SMSC CORPORATION ]
