cs8904 Cirrus Logic, Inc., cs8904 Datasheet - Page 19

• Manufacturer Part Number: cs8904
• Description: Crystal Lan? Quad Ethernet Transceiver
• Manufacturer: Cirrus Logic, Inc.

DS191PP2
Port Loopback causes the 10BASE-T transmitter to
be idled and the 10BASE-T receiver to be
disconnected. In addition, data received from the
controller on the TxDATA pin is looped back on
the RxDATA pin to the controller. Both CD and
RxCLOCK are provided to synchronize the
transfer to the controller. Note that since the port is
isolated from the external Ethernet network,
collisions will not occur.
CS8904
Crystal LAN™ Quad Ethernet Transceiver
CIRRUS LOGIC ADVANCED PRODUCT DATABOOK
4.4 External Clock Oscillator
A 20-MHz quartz crystal or CMOS clock input is
required by the CS8904. If a CMOS clock input is
used, it should be connected the to XTAL1 pin,
with the XTAL2 pin left open. The clock signal
should be 20 MHz ±0.01% with a duty cycle
between 45% and 55%. The specifications for the
crystal are described in the External Clock section
of the DC CHARACTERISTICS Table.
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