243658-020 Datasheet, PDF (33/128 Pages) Intel Corporation – Intel Celeron Processor up to 1.10 GHz

Intel^® Celeron^® Processor up to 1.10 GHz
2.11
AGTL+ System Bus Specifications
It is recommended that the AGTL+ bus be routed in a daisy-chain fashion with termination
resistors to VTT at each end of the signal trace. These termination resistors are placed electrically
between the ends of the signal traces and the VTT voltage supply and generally are chosen to
approximate the substrate impedance. The valid high and low levels are determined by the input
buffers using a reference voltage called VREF. Single ended termination may be possible if trace
lengths are tightly controlled, see the Intel^® 440EX AGPset Design Guide (Order Number 290637)
or the Intel^® Celeron ^® Processor (PPGA) with the Intel^® 440LX AGPset Design Guide (Order
Number 245088) for more information.
Table 8 below lists the nominal specification for the AGTL+ termination voltage (VTT). The
AGTL+ reference voltage (VREF) is generated on the processor substrate (S.E.P. Package only) for
the processor core, but should be set to ²/₃ VTT for other AGTL+ logic using a voltage divider on
the motherboard. It is important that the motherboard impedance be specified and held to:
• ±20% tolerance (S.E.E.P. and PPGA)
• ±15% tolerance (FC-PGA/FC-PGA2)
It is also important that the intrinsic trace capacitance for the AGTL+ signal group traces is known
and well-controlled. For more details on AGTL+, see the Pentium^® II Processor Developer's
Manual (Order Number 243502) and AP-585, Pentium^® II Processor AGTL+ Guidelines (Order
Number 243330).
Table 8. Processor AGTL+ Bus Specifications
Symbol
VTT
RTT
VREF
Parameter
Bus Termination Voltage
• S.E.P.P and PPGA
• FC-PGA/FC-PGA2
Termination Resistor
• S.E.P.P and PPGA
• FC-PGA/FC-PGA2
(on die RTT)
Bus Reference Voltage
• S.E.P.P and PPGA
• FC-PGA/FC-PGA2
Min
1.365
40
0.950
Typ
1.50
1.50
56
2_{/3 VTT}
2/3 VTT
Max
1.635
130
1.05
Units
Notes
V 1.5 V ± 9% ²
V4
Ω ± 5%
Ω5
V
± 2% ³
V6
NOTES:
1. Unless otherwise noted, all specifications in this table apply to all Celeron processor frequencies.
2. VTT must be held to 1.5 V ± 9%; dICCVTT/dt is specified in Table 5. It is recommended that VTT be held to
1.5 V ± 3% while the Intel Celeron processor system bus is idle. This is measured at the processor edge
fingers.
3. VREF is generated on the processor substrate to be ²/₃ VTT nominally with the S.E.P. package. It must be
created on the motherboard for processors in the PPGA package.
4. VTT and Vcc_1.5 must be held to 1.5V ±9%. It is required that VTT and Vcc_1.5 be held to 1.5 V ±3% while the
processor system bus is idle (static condition). This is measured at the PGA370 socket pins on the bottom
side of the baseboard.
5. The value of the on-die R_TT is determined by the resistor value measured by the RTTCTRL signal pin. The
on-die R_TT tolerance is ±15% based on the RTTCTRL resistor pull-down of ±1%. See Section 7.0 for more
details on the RTTCTRL signal. Refer to the recommendation guidelines for the specific chipset/processor
combination.
6. VREF is generated on the motherboard and should be 2/3 VTT ±2% nominally. Insure that there is adequate
VREF decoupling on the motherboard.
Datasheet
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