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Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
SMSC LAN8720/LAN8720i 17 Revision 1.0 (05-28-09)
DATASHEET
3.5 10/100 Line Interface Signals
3.6 Analog Reference
3.7 Power Signals
Table 3.6 10/100 Line Interface Signals 24-QFN
SIGNAL
NAME
24-QFN
PIN # TYPE DESCRIPTION
TXP 21 AIO Transmit/Receive Positive Channel 1.
TXN 20 AIO Transmit/Receive Negative Channel 1.
RXP 23 AIO Transmit/Receive Positive Channel 2.
RXN 22 AIO Transmit/Receive Negative Channel 2.
Table 3.7 Analog References 24-QFN
SIGNAL
NAME
24-QFN
PIN # TYPE DESCRIPTION
RBIAS 24 AI External 1% Bias Resistor. Requires an 12.1k resistor to ground connected
as described in the Analog Layout Guidelines. The nominal voltage is 1.2V
and therefore the resistor will dissipate approximately 1mW of power.
Table 3.8 Power Signals 24-QFN
SIGNAL
NAME
24-QFN
PIN # TYPE DESCRIPTION
VDDIO
9 P +1.6V to +3.6V Variable I/O Pad Power
VDDCR 6 P +1.2V (Core voltage) - 1.2V for digital circuitry on chip. Supplied by the on-
chip regulator unless configured for regulator off mode using the
RXCLK/REGOFF pin. A 1uF decoupling capacitor to ground should be used
on this pin when using the internal 1.2V regulator.
VDD1A 19 P +3.3V Analog Port Power to Channel 1.
VDD2A 1 P +3.3V Analog Port Power to Channel 2 and to internal regulator.
VSS FLAG GND The flag must be connected to the ground plane with a via array under the
exposed flag. This is the ground connection for the IC.