L80223 LSI, L80223 Datasheet - Page 128

• Manufacturer Part Number: L80223
• Manufacturer: LSI

Specifications of L80223

• Lead Free Status / RoHS Status: Not Compliant

A.3 TP Receive Interface
A-6
IEEE 802.3. These two external resistors must be connected between
V
provide the correct termination impedance when looking back through
the transformer from the twisted-pair cable, as shown in
through
depends on the type of cable the device drives.
To minimize common-mode output noise and to aid in meeting radiated
emissions requirements, it may be necessary to add a common-mode
choke on the transmit outputs as well as add common-mode bundle
termination. The qualified transformers mentioned in
common-mode chokes along with the transformers on both the transmit
and receive sides, as shown in
mode bundle termination may be needed and can be achieved when the
unused pairs in the RJ45 connector are connected to chassis ground
through 75 ohm resistors and a 0.01 F capacitor, as shown in
Figure A.1
To minimize noise pickup into the transmit path in a system or on a PCB,
the loading on TPO should be minimized, and both outputs should
always be loaded equally.
Receive data is typically transformer coupled into the receive inputs on
TPI and terminated with external resistors as shown in
through
The transformer for the receiver should have a winding ratio of 1:1, as
shown in
transformer are shown in
listed in
The receive input must be terminated with the correct termination
impedance to meet the input impedance and return loss requirements of
IEEE 802.3. In addition, the receive TP inputs must be attenuated. Both
the termination and attenuation is accomplished with four external
resistors in series across the TPI inputs, as shown in
Figure
and the total series resistance should be equal to the characteristic
impedance of the cable (100 ohm for UTP). It is also recommended that
Application Information
DD
and each of the TPO outputs. Their value should be chosen to
A.3. Each resistor should be 25% of the total series resistance,
Figure
Figure
Table
Figure A.1
through
A.2.
A.3. The value of these two external termination resistors
A.3.
Copyright © 2000, 2001, 2002 by LSI Logic Corporation. All rights reserved.
Figure
through
Table A.1
A.3.
Figure
Figure A.1
and sources for the transformer are
A.3. The specifications for this
through
Figure
Table A.2
Figure A.1
Figure A.1
Figure A.1
A.3. common-
all contain
through