Intel QX9775 EU80574XL088N Data Sheet

32

Routing topologies are dependent on the processors supported and the chipset used in 

the design. In most cases, termination resistors are not required as these are 

integrated into the processor silicon. See 

 for details on which signals do not 

include on-die termination. Refer to 

 for R

TT

 values.

Valid high and low levels are determined by the input buffers via comparing with a 

reference voltage called GTLREF_DATA_MID, GTLREF_DATA_END, GTLREF_ADD_MID, 

and GTLREF_ADD_END. GTLREF_DATA_MID and GTLREF_DATA_END is the reference 

voltage for the FSB 4X data signals, GTLREF_ADD_MID, and GTLREF_ADD_END is the 

reference voltage for the FSB 2X address signals and common clock signals. 

lists the GTLREF_DATA_MID, GTLREF_DATA_END, GTLREF_ADD_MID, and 

GTLREF_ADD_END specifications.

The AGTL+ reference voltages (GTLREF_DATA_MID, GTLREF_DATA_END, 

GTLREF_ADD_MID, and GTLREF_ADD_END) must be generated on the baseboard 

using high precision voltage divider circuits. 

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 system 
designer to calculate the minimum values across the range of V

TT

.

3.

GTLREF_DATA_MID, GTLREF_DATA_END, GTLREF_ADD_MID, and GTLREF_ADD_END is 
generated from V

TT

 on the baseboard by a voltage divider of 1% resistors. The minimum 

and maximum specifications account for this resistor tolerance. The V

TT

 referred to in 

these specifications is the instantaneous V

TT

.

4.

R

TT

 is the on-die termination resistance measured at V

OL

 of the AGTL+ output driver. 

Measured at 0.31*V

TT

. R

TT

 is connected to V

TT

 on die.

5.

COMP resistance must be provided on the system board with 1% resistors. 

GTLREF_DATA_MID, 
GTLREF_DATA_END

Data Bus Reference 
Voltage

0.98 * 0.667 

* V

TT

0.667 * V

TT

1.02*0.667 

* V

TT

V

2,  3

GTLREF_ADD_MID, 
GTLREF_ADD_END

Address Bus 
Reference Voltage

0.98 * 0.667 

* V

TT

0.667 * V

TT

1.02*0.667 

* V

TT

V

2,  3

R

TT

Termination 
Resistance (pull up)

45

50

55

Ω

4

COMP

COMP Resistance

49.4

49.9

50.4

Ω

5