
Introduction
39
September 2005
SCPS110
Table 219. IEEE 1394 Physical Layer Terminals
Table 219 is only applicable to the PCI4512, PCI7402, PCI7412, PCI7612, PCI8402, and PCI8412
controllers.
TERMINAL
DESCRIPTION
I/O
INPUT
OUTPUT
EXTERNAL
PIN STRAPPING
NAME
NO.
DESCRIPTION
I/O
TYPE
INPUT
OUTPUT
EXTERNAL
COMPONENTS
PIN STRAPPING
(IF UNUSED)
CPS
R12
Cable power status input. This terminal is normally
connected to cable power through a 400-k
resistor. This
circuit drives an internal comparator that is used to detect the
presence of cable power. If CPS is not used to detect cable
power, then this terminal must be pulled to GND.
AF
390-k
series
resistor to
BUSPOWER if
providing power
through the 1394
port
Tie to GND
R0
R1
T18
T19
Current-setting resistor terminals. These terminals are
connected to an external resistance to set the internal
operating currents and cable driver output currents. A
resistance of 6.34 k
±1% is required to meet the IEEE Std
1394-1995 output voltage limits.
AF
6.34-k
±1%
resistor between
R0 and R1 per
1394 specification
Tie to GND
TPA0P
TPA0N
V14
W14
Twisted-pair cable A differential signal terminals. Board trace
lengths from each pair of positive and negative differential
signal pins must be matched and as short as possible to the
I/O
TP
1394 termination
(see reference
schematics)
Float
TPA1P
TPA1N
V16
W16
signal pins must be matched and as short as possible to the
external load resistors and to the cable connector. For an
unused port, TPA+ and TPA can be left open.
I//O
TP
1394 termination
(see reference
schematics)
Float
TPBIAS0
TPBIAS1
R13
W17
Twisted-pair bias output. This provides the 1.86-V nominal
bias voltage needed for proper operation of the twisted-pair
cable drivers and receivers and for signaling to the remote
nodes that there is an active cable connection. Each of these
pins must be decoupled with a 1.0-
F capacitor to ground.
AF
1394 termination
(see reference
schematics)
Float
TPB0P
TPB0N
V13
W13
Twisted-pair cable B differential signal terminals. Board trace
lengths from each pair of positive and negative differential
signal pins must be matched and as short as possible to the
I/O
TP
1394 termination
(see reference
schematics)
Float
TPB1P
TPB1N
V15
W15
signal pins must be matched and as short as possible to the
external load resistors and to the cable connector. For an
unused port, TPB+ and TPB must be pulled to ground.
I/O
TP
1394 termination
(see reference
schematics)
Float
XI
XO
R19
R18
Crystal oscillator inputs. These pins connect to a
24.576-MHz parallel resonant fundamental mode crystal.
The optimum values for the external shunt capacitors are
dependent on the specifications of the crystal used (see
Section 3.9.2, Crystal Selection). An external clock input can
be connected to the XI terminal. When using an external
clock input, the XO terminal must be left unconnected, and
the clock must be supplied before the controller is taken out
of reset. Refer to Section 3.9.2 for the operating
characteristics of the XI terminal.
AF
24.576-MHz
oscillator (see
implementation
guide)
Float
These terminals are reserved for the PCI6412 and PCI6612 controllers.
Table 220. No Connect Terminals
TERMINAL
DESCRIPTION
PIN STRAPPING
NAME
NUMBER
DESCRIPTION
PIN STRAPPING
NC
U12, V12, W12
No connect. These terminals do not have a connection anywhere on this device.
Float
NC
E05
No connect. This terminal is an identification ball used for device orientation.
Float