CST7061GMb

Rev. 2 2/27/98

Miniature Token Ring Transceiver Module

Typical Application Circuit Connection to TI380C60 (or Equivalent). Only NIC side shown.

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

EPT7061GM

The circuit below is a guideline for interconnecting PCA’s EPT7061GM with a typical Token Ring PHY chip for 4 Mb/16Mb

applications over STP or UTP cable.

Further details of system design should be obtained from the specific chip

manufacturer. Note that this module is optimized for a “voltage source” driver such as TI380C60. Only one type of cable

should be driven by the module: either UTP or STP.

Note that the two channels have identical filtering and other magnetics . This option is seen to be widely used by system

designers when designing dedicated Token Ring systems.

The pull down resistors to chassis via a cap shown around the RJ45 connector have been known to suppress unwanted

radiation that unused wires pick up from the immediate environment. This is specially true if driving UTP cable. Their

placement and use are to be considered carefully before a design is finalized.

No specific recommendation is made here for phantom return circuitry: implementation varies. Please note that additional

emission control has been observed if both nodes of the phantom bypass capacitor on the transmit channel are pulled to

the chassis ground via suitable capacitors.

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 EPT7061GM. There need not be any ground plane beyond

this point.

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

Ω (UTP), balanced and well coupled to

achieve minimum radiation from these traces.

Notes : 1. Pins 3 & 4 are left unconnected. Applications vary. Your system may have a phantom drive return

detection circuit needing pins 3 & 4 to be connected separately.

DTR PHY

Rcv-

PHOUTA

50

Ω/2W

50

Ω/2W

EPT7061GM

2

1

14

7

8

9

10

100

Ω

Rcv+

PHOUTB

Xmit-

Xmit+

13

15

16

+5V

+5V

10

µF

10

µF

RJ45

4

5

3

6

8

7

12

Xmit

±

100

Ω

Rcv

±

3

4

PH-A

PH-B

TEL: (818) 892-0761

FAX: (818) 894-5791

http://www.pca.com

PCA ELECTRONICS, INC.

16799 SCHOENBORN ST.

NORTH HILLS, CA 91343