Electrical Specifications
2.7.3.1
GTL+ Front Side Bus Specifications
In most cases, termination resistors are not required as these are integrated into the
processor silicon. See Table 9 for details on which GTL+ signals do not include on-die
termination.
Valid high and low levels are determined by the input buffers by comparing with a
reference voltage called GTLREF. Table 14 lists the GTLREF specifications for both
50 Ohm and 60 Ohm platforms. The GTL+ reference voltage (GTLREF) should be
generated on the system board using high precision voltage divider circuits.
Table 14.
GTL+ Bus Voltage Definitions
Symbol
Parameter
Min
Typ
Max
Units Notes1
GTLREF_PU GTLREF pull up resistor
GTLREF_PD GTLREF pull down resistor
124 * 0.99
210 * 0.99
45
124
210
50
124 * 1.01
210 * 1.01
55
Ω
Ω
Ω
2, 4
3
RTT
Termination Resistance
60 Ω Platform termination
Resistance
60.4 * 0.99
49.9 * 0.99
30.1 * 0.99
24.9 * 0.99
60.4
49.9
30.1
24.9
60.4 * 1.01
49.9 * 1.01
30.1 * 1.01
24.9 * 1.01
Ω
Ω
Ω
Ω
4
4
4
4
COMP[3:0]
50 Ω Platform termination
Resistance
60 Ω Platform termination
Resistance
COMP8
50 Ω Platform termination
Resistance
NOTES:
1.
2.
Unless otherwise noted, all specifications in this table apply to all processor frequencies.
GTLREF is to be generated from VTT by a voltage divider of 1% resistors (one divider for
each GTLEREF land).
3.
4.
R
TT is the on-die termination resistance measured at VTT/3 of the GTL+ output driver.
COMP resistance must be provided on the system board with 1% resistors. COMP[3:0] and
COMP8 resistors are to VSS
.
Datasheet
27
INTEL [ INTEL ]
