TSB21LV03

IEEE 1394-1995 TRIPLE-CABLE TRANSCEIVER/ARBITER

SLLS230A – MARCH 1996 – REVISED DECEMBER 1996

17

POST OFFICE BOX 655303

APPLICATION INFORMATION

Digital VCR

Phy

Digital VCR

1394 Cable

Logic

Ground

AC Input

Phy

AC Input

Isolated

Power

Supply

Isolated

Power

Supply

Figure 6. Isolation By Way of Isolated Power Supplies

When a camera is powered only from the IEEE 1394-1995 cable, it would not normally be connected to a

green-wire ground and probably would not require isolation to be incorporated in this particular node

configuration (see Figure 7).

Digital VCR

Phy

Camera

1394 Cable

Logic

Ground

AC Input

Phy

Isolated

Power

Supply

Figure 7. Leaf Node Not Requiring Isolation

In the case of a peripheral that is battery powered and using the 4-signal wire audio/video cable where there

is no cable-power logic ground or cable-power wire in the 1394 cable, it probably would not be connected to

a green-wire ground. However, there is still the potential that a battery- or cable-powered leaf node may be

grounded through some accessory device. Figure 8 shows an example where the shield isolation is not

implemented correctly.