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Figure 3-2 6-pin FireWire connector
Table 3-2 Pin assignments on the 6-pin FireWire connector
DescriptionSignal namePin
Unregulated DC; 12.8 VPower1
Ground return for power and inner cable shieldGround2
Twisted-pair B, differential signalsTPB-3
Twisted-pair B, differential signalsTPB+4
Twisted-pair A, differential signalsTPA-5
Twisted-pair A, differential signalsTPA+6
Outer cable shield—Shell
When the computer is on or the power adapter is connected, the power pin provides a maximum voltage
of 12.8 V (no load) and 7 W power per port. Maximum output current for both ports combined is 1.5 A and
is controlled by a self-resetting fuse.
Pin 2 of the 6-pin FireWire connector is ground for both power and the inner cable shield. If a4-pin connector
is used on the other end of the FireWire cable, its shell should be connected to the wire from pin 2.
The signal pairs are crossed in the cable itself so that pins 5 and 6 at one end of the cable connect with pins
3 and 4 at the other end. When transmitting, pins 3 and 4 carry data and pins 5 and 6 carry clock; when
receiving, the reverse is true.
FireWire 800 Connector
The FireWire 800 port on the PowerBook G4 17-inch computer is based on IEEE 1394b and enables a 800
Mbps transfer rate. FireWire 800 uses a 9-pin connector and is backwards compatible with original 1394
FireWire devices with 6-pin or 4-pin connectors. With the appropriate cable, the new 9-pin port works
seamlessly with legacy FireWire devices. Cables are available to go from both 6-pin and 4-pin connectors to
a 9-pin, and 9-pin to 9-pin.
FireWire Ports 27
Legacy Document | 2003-03-01 | © 2003 Apple Computer, Inc. All Rights Reserved.
CHAPTER 3
Devices and Ports