Datasheet
31
Electrical Specifications
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 VCC.
3. GTLREF is generated from VCC on the baseboard by a voltage divider of 1% resistors. Refer to the
appropriate platform design guidelines for implementation details.
4. RTT is the on-die termination resistance measured from VCC to 1/3 VCC at the AGTL+ output driver.
5. COMP resistors are pull downs to V
SS provided on the baseboard with 1% tolerance. See the appropriate
platform design guidelines for implementation details.
6. The VCC referred to in these specifications refers to instantaneous VCC.
7. COMP value may vary with chipset.
8. The values for RTT and COMP noted as ‘New Designs’ apply to designs that will not support Intel Xeon
processor MP (previously code named Foster MP). These designs are optimized for the Intel Xeon processor
MP on the 0.13 micron process processor.
2.13
System Bus AC Specifications
The processor system bus timings specified in this section are defined at the processor core (pads).
See
Section 9 for the Intel Xeon processor MP on the 0.13 micron process processor pin listing and
signal definitions.
Table 15 through
Table 20 list the AC specifications associated with the processor system bus.
Specific parameters for a 400 MHz system bus are listed in these tables.
All AGTL+ timings are referenced to GTLREF for both ‘0’ and ‘1’ logic levels unless otherwise
specified.
AGTL+ layout guidelines are also available in the appropriate platform design guidelines.
Note:
Care should be taken to read all notes associated with a particular timing parameter
Table 14. AGTL+ Bus Voltage Definitions
Symbol
Parameter
Min
Typ
Max
Units
Notes 1
GTLREF
Bus Reference Voltage
2/3 VCC - 2%
2/3 VCC
2/3 VCC + 2%
V
2, 3, 6
GTLREF
New Design
Bus Reference Voltage
0.63*VCC - 2%
0.63*VCC
0.63*VCC + 2%
V
2, 3, 6
RTT
Termination Resistance
36
41
46
4
RTT
New Design
Termination Resistance
45
50
55
4, 8
COMP[1:0]
COMP Resistance
42.77
43.2
43.63
5, 7
COMP[1:0]
New Design
COMP Resistance
49.55
50
50.45
5, 7, 8