Mobile Intel Pentium 4 Processor with 533 MHz Front Side Bus

Mobile Intel
®
Pentium
®
4 Processor with 533 MHz System Bus Datasheet 33
Electrical Specifications
2.13 GTL+ FSB Specifications
Routing topology recommendations may be found in the appropriate platform design guidelines
listed in Table 1. Termination resistors are not required for most GTL+ signals, as these are
integrated into the processor silicon.
Valid high and low levels are determined by the input buffers which compare a signal’s voltage
with a reference voltage called GTLREF (known as V
REF
in previous documentation).
Table 16 lists the GTLREF specifications. The GTL+ reference voltage (GTLREF) should be
generated on the system board using high precision voltage divider circuits. It is important that the
system board impedance is held to the specified tolerance, and that the intrinsic trace capacitance
for the GTL+ signal group traces is known and well-controlled. For more details on platform
design see the appropriate platform design guidelines listed in Table 1.
NOTES:
1. Unless otherwise noted, all specifications in this table apply to all processor frequencies.
2. The tolerances for this specification have been stated generically to enable the system designer to calculate
the minimum and maximum values across the range of V
CC
.
3. GTLREF should be generated from V
CC
by a voltage divider of 1% tolerance resistors or 1% tolerance
matched resistors. Refer to the appropriate platform design guidelines for implementation details.
4. R
TT
is the on-die termination resistance measured at V
OL
of the GTL+ output driver. Refer to processor I/O
buffer models for I/V characteristics.
5. COMP resistance must be provided on the system board with 1% tolerance resistors. See the appropriate
platform design guidelines listed in Table 1 for implementation details.
6. The V
CC
referred to in these specifications is the instantaneous V
CC
.
7. For a platform to be forward compatible with future Portable processors it must be designed to support an Rtt
value of 60 Ω and a GTLREF value of 0.63*Vcc. A compatible platform is one that is designed for some level
of compatibility with future portable processors.
Table 16. GTL+ Bus Voltage Definitions
Symbol Parameter Min Typ Max Units Notes
1
GTLREF
Bus
Reference
Voltage
2/3 V
CC
-2% 2/3 V
CC
2/3 V
CC
+2% V 2, 3, 6, 7
GTLREF
_COMPATIBLE
Bus
Reference
Voltage
0.63 V
CC
-2% 0.63 V
CC
0.63 V
CC
+2% V 2, 3, 6, 7
R
TT
Termination
Resistance
45 50 55 Ω 4, 7
R
TT_COMPATIBLE
Termination
Resistance
54 60 66 Ω 4, 7
COMP[1:0]
COMP
Resistance
50.49 51 51.51 Ω 5, 7
COMP[1:0]
_COMPATIBLE
COMP
Resistance
61.3 61.9 62.5 Ω 5, 7