L80223 LSI, L80223 Datasheet - Page 130

• Manufacturer Part Number: L80223
• Manufacturer: LSI

Specifications of L80223

• Lead Free Status / RoHS Status: Not Compliant

A.5 Transmitter Droop
A.6 MII Controller Interface
A.6.1 Clocks
A-8
the device when the 10 Mb
selected.
Keep REXT as close to the REXT and GND pins as possible to reduce
noise pickup into the transmitter.
Because the TP output is a current source, capacitive and inductive
loading can reduce the output voltage from the ideal level. Thus, in actual
application, it might be necessary to adjust the value of the output
current to compensate for external loading. One way to adjust the TP
output level is to change the value of the external resistor connected to
REXT.
The IEEE 802.3 specification has a transmit output droop requirement for
100BASE-TX. Because the L80227 TP output is a current source, it has
no perceptible droop by itself. However, the inductance of the transformer
added to the device transmitter output as shown in
Figure A.3
wire. If the transformer connected to the L80227 outputs meets the
requirements of
meets the IEEE 802.3 droop requirements.
The MII controller interface allows the L80227 to connect to any external
Ethernet controller without any glue logic, provided the external Ethernet
controller has an MII interface that complies with IEEE 802.3, as shown
in
Standard Ethernet controllers with an MII use TX_CLK to clock data in
on TXD[3:0]. TX_CLK is specified in IEEE 802.3 and on the L80227 to
be an output. If a nonstandard controller or other digital device is used
to interface to the L80227, there might be a need to clock TXD[3:0] into
the L80227 on the edges of an external master clock. The master clock,
in this case, would be an input to the L80227. To do this, use OSCIN as
Application Information
Figure A.1
causes droop to appear at the transmit interface to the TP
through
Table
Copyright © 2000, 2001, 2002 by LSI Logic Corporation. All rights reserved.
Figure
A.1, the transmit interface to the TP cable then
its/
A.3.
s mode or UTP120/STP150 modes are
Figure A.1
through