SLLS418G
–
JUNE 2000
–
REVISED JANUARY 2003
9
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
Terminal Functions (Continued)
TERMINAL
I/O
DESCRIPTION
NAME
SM
TYPE
CMOS
NO.
33
I
Test control input. This input is used in the manufacturing test of the TSB41AB3. For normal use
this terminal is tied to GND.
SYSCLK
CMOS
2
O
System clock output. Provides a 49.152-MHz clock signal, synchronized with data transfers, to
the LLC.
TESTM
CMOS
31
I
Test control input. This input is used in the manufacturing test of the TSB41AB3. For normal use
this terminal is tied to VDD through a 1-k
resistor.
TPA0+
TPA1+
TPA2+
Cable
45
52
58
I/O
Twisted-pair cable A differential-signal terminals. Board traces from each pair of positive and
negative differential signal terminals must be kept matched and as short as possible to the
negative differential signal terminals must be ke t matched and as short as ossible to the
external load resistors and to the cable connector. For an unused port, TPA+ and TPA
–
can be left
open.
TPA0
–
TPA1
–
TPA2
–
Cable
44
51
57
I/O
TPB0+
TPB1+
TPB2+
Cable
43
50
56
I/O
Twisted-pair cable B differential-signal terminals. Board traces from each pair of positive and
negative differential signal terminals should be kept matched and as short as possible to the
negative differential signal terminals should be ke t matched and as short as ossible to the
external load resistors and to the cable connector. For an unused port, TPB+ and TPB
–
can be left
open.
TPB0
–
TPB1
–
TPB2
–
Cable
42
49
55
I/O
TPBIAS0
TPBIAS1
TPBIAS2
Cable
46
53
59
I/O
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 terminals, except for an unused port, must be
decoupled with a 1.0-
μ
F capacitor to ground. For the unused port, this terminal can be left
unconnected.
VDD-5V
Supply
9
–
5-V VDD terminal. This terminal must be connected to the LLC VDD supply when a 5-V LLC is
used, and connected to the PHY DVDD when a 3-V LLC is used. A combination of high-frequency
decoupling capacitors near this terminal is suggested, such as paralleled 0.1
μ
F and 0.001
μ
F.
When this terminal is tied to a 5-V supply, all terminal bus holders are disabled, regardless of the
state of the ISO terminal. When this terminal is tied to a 3-V supply, bus holders are enabled when
the ISO terminal is high.
XI
XO
Crystal
76
77
–
Crystal oscillator inputs. These terminals 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
crystal selection
in the Applications Information section).
When an external clock source is used, XI should be the input and XO should be left open, and the
clock must be supplied before the device is taken out of reset.
NOTE: It is strongly recommended that signals tied to VDD use a 1-k
resistor (minimum). Tying signals directly to VCC may result in ESD failures.
Signals tied to ground may be tied directly.