TSB17BA1

IEEE STD 1394b SINGLEPORT CABLE TRANSCEIVER

SLLS568C − JANUARY 2004 − REVISED MARCH 2004

9

POST OFFICE BOX 655303

APPLICATION INFORMATION

1394 Link

1394b PHY

Termination

and

Transformer

RJ45

UTP Cable

Termination

TSB17BA1

Figure 3. 1394b Cable Termination

signal coding

The signaling generated from a 1394b PHY is 8B/10B encoded. This means to send 8 bits of data requires the

transmission of 10 bits across the cable. The maximum frequency that is required to send 100 Mbits/s is a

fundamental frequency of 62.5 MHz (see the IEEE Std 1394b-2002 for more explanation).

connector pins

The current IEEE Std 1394b-2002 requires that the connection from 1394b PHY signal to the RJ45 connector

pin be:

There is a proposal to change the IEEE Std 1394b-2002 connection from 1394b PHY signal to the RJ45

connector pin to be the same as the 100baseT Ethernet. This allows use of more 100baseT Ethernet

components for 1394b connections. This changes the connections to:

It is anticipated that the change will be implemented into IEEE Std 1394b-2002, though it has not been ratified.

Therefore, it is recommended that all implementations utilize the new pinout running TPA+ to pin 3 and TPA−

to pin 6. If a closed system is created, meaning the designer controls the electronics at both ends of the UTP5

cable, then using pins 7 and 8 can give as much as a 12-dB reduction in crosstalk rather than using pins 3 and

6. Please contact Texas Instruments for further details.

cable connection

The IEEE Std 1394b-2002 requires the output of a TPB port to be connected to the input of a TPA port when

connecting one device to a second device. In other words, it requires a crossover somewhere between the two

PHY ports. The 1394b standard further states that a UTP5 device incorporates logic that can automatically

implement this crossover in the logic. The TSB17BA1 does not contain this logic, therefore, the crossover must

be implemented external to the TSB17BA1.

It is recommended for users of the TSB17BA1 to:

The crossover cable connects: