CSF8048Gb

Rev. 1

1/7/97

100 Base-X Interface Module

The circuit below is a guideline for interconnecting PCA’s EPF8048G with ML6692 or ML6694 chip applications. Further

details can be obtained from the chip manufacturer application notes.

Typical insertion loss of the isolation transformer is 0.5dB. This parameter covers the entire spectrum of the encoded

signals in 100 BX protocol. Under terminated conditions, to transmit a 2V pk-pk signal across the cable, you must adjust

the chips supporting resistor to get at least 2.12V pk-pk across the transmit pins.

Note that in the 100 BX application, you do not need a split primary. The reason is that there is no 10 Base T to negotiate.

The receiver side can be terminated as shown or by a single 100 ohms with primary center tap taken to ground via a suitible

cap.Note that in the 100 BX application, you do not need a split primary. The reason is that there is no 10 Base-T to

negotiate. The receiver side can be terminated as shown or by a single 100 ohms with primary center tap taken to ground

via a suitible cap. NOTE THAT THIS PART DOES NOT HAVE A TRANSMIT CHANNEL CENTER TAP ON THE CABLE SIDE.

Sufficient common mode attenuation is provided by the high performance common mode chokes on chip side as well as the

cable side thus making this part easy to manufacture at reduced costs. A proper system board design may allow some

users to benefit from this simplified structure of the transmit channel.

The phantom resistors shown around the connector have been known to suppress unwanted radiation that unused wires

pick up from the immediate environment. Their placement and use are to be considered carefully before a design is

finalized.

It is recommended that there be a neat separation of ground planes in the layout. It is generally accepted practice to limit

the plane off at least 0.05 inches away from the chip side pins of EPF8048G. There need not be any ground plane beyond

this plane.

For best results, PCB designer should design the outgoing traces preferably to be 50

Ω, balanced and well coupled to

achieve minimum radiation from these traces.

Typical Application Circuit for UTP

EPF8048G

E L E C T R O N I C S I N C .

TEL: (818) 892-0761

FAX: (818) 894-5791

http://www.pca.com

PCA ELECTRONICS, INC.

16799 SCHOENBORN ST.

NORTH HILLS, CA 91343

Notes : * NIC Side is shown. Hub side connection will swap pins 3-6 with 1-2.

ML6692

or

ML6694

RJ45*

1

2

6

3

4

5

7

8

TX+

TX-

RX+

RX-

Chassis

Ground

50

Ω

50

Ω

EPF8048G

Xmit

Rcv

3

Capacitor

+5V

1

2

16

15

8

7

9

10

.1

µF

14