Intel Celeron D Processor 3xx Sequence
30 Datasheet
Electrical Specifications
2.13 GTL+ FSB Specifications
Termination resistors are not required for most GTL+ signals; they are integrated into the processor
silicon.
Valid high and low levels are determined by the input buffers that compare a signal’s voltage with a
reference voltage called GTLREF. Table 2-18 lists the GTLREF specifications. The GTL+
reference voltage (GTLREF) should be generated on the system board using high precision voltage
divider circuits.
§
Table 2-18. GTL+ Bus Voltage Definitions
Symbol Parameter Min Typ Max Units Notes
1
NOTES:
1. Unless otherwise noted, all specifications in this table apply to all processor frequencies.
GTLREF
_compatible
Bus Reference Voltage 0.98 * (2/3 V
CC
)2/3 V
CC
1.02 * (2/3 V
CC
)V
2,3,4,5
2. The tolerances for this specification have been stated generically to enable the system designer to calculate the mini-
mum and maximum values across the range of V
CC
.
3. GTLREF should be generated from V
CC
by a voltage divider of 1% resistors or 1% matched resistors.
4. The V
CC
referred to in these specifications is the instantaneous V
CC
.
5. These specifications are different depending on whether the platform is forward compatible to the Celeron D processor
or if it is optimized for the Celeron D processor. A compatible platform is one that is designed for a previous generation
processor but has some level of compatibility with the Celeron D processor. An optimized platform is one designed spe-
cifically for the Celeron D processor; however, it may have some level of compatibility with previous generation proces-
sors.
GTLREF
_optimized
Bus Reference Voltage (0.98 * 0.63) * V
CC
0.63 * V
CC
(1.02 * 0.63) * V
CC
V
2,3,4,5
R
_pullup
On die pull-up for
BOOTSELECT and
OPTIMIZED/
COMPAT# pins
500 — 5000 Ω
5,6
6. These pull-ups are to the internal V
CCVID
supply.
R
TT_compatible
Termination
Resistance
45 50 55 Ω
5,7
7. R
TT
is the on-die termination resistance measured at V
CC
/2 of the GTL+ output driver.
R
TT_optimized
Termination
Resistance
54 60 66 Ω
5
COMP[1:0]
_compatible
COMP Resistance 49.4 49.9 50.4 Ω
5,8
8. COMP resistance must be provided on the system board with 1% resistors.
COMP[1:0]
_optimized
COMP Resistance 61.3 61.9 62.5 Ω
5,8