pga370 ETC-unknow, pga370 Datasheet - Page 48

• Manufacturer Part Number: pga370
• Description: Mpu Pentium Iii 64-bit 0.18um 700mhz 370-pin Fcpga
• Manufacturer: ETC-unknow

Pentium
3.3
3.3.1
48
Figure 17. Low to High AGTL+ Receiver Ringback Tolerance
®
III Processor for the PGA370 Socket at 500 MHz to 1.13 GHz
AGTL+ Signal Quality Specifications and Measurement
Guidelines
Overshoot/Undershoot Guidelines
Overshoot (or undershoot) is the absolute value of the maximum voltage above the nominal high
voltage or below V
signal edge rates. The processor can be damaged by repeated overshoot events on 1.5 V or 2.5 V
tolerant buffers if the charge is large enough (i.e., if the overshoot is great enough). Determining
the impact of an overshoot/undershoot condition requires knowledge of the magnitude, the pulse
direction and the activity factor (AF). Permanent damage to the processor is the likely result of
excessive overshoot/undershoot. Violating the overshoot/undershoot guideline will also make
satisfying the ringback specification difficult.
When performing simulations to determine impact of overshoot and overshoot, ESD diodes must
be properly characterized. ESD protection diodes do not act as voltage clamps and will not provide
overshoot or undershoot protection. ESD diodes modeled within Intel I/O Buffer models do not
clamp undershoot or overshoot and will yield correct simulation results. If other I/O buffer models
are being used to characterize the Pentium III processor performance, care must be taken to ensure
that ESD models do not clamp extreme voltage levels. Intel I/O Buffer models also contain I/O
capacitance characterization. Therefore, removing the ESD diodes from an I/O Buffer model will
impact results and may yield excessive overshoot/undershoot.
6. Intel recommends simulations not exceed a ringback value of V
7. A negative value for
8.
sources of system noise.
signal cannot ringback below V
and : are measured relative to V
V
V
REF
REF
Note: High to low case is analogous
+ 0.2
V
- 0.2
REF
SS
. The overshoot guideline limits transitions beyond V
indicates that the amplitude of ringback is above V
V
start
REF
REF
+ 100 mV).
. : is measured relative to V
Time
0.7V Clk Ref
REF
REF
±200 mV to allow margin for other
+ 200 mV.
REF
Clock
. (i.e.,
CC
or V
= -100 mV specifies the
SS
due to the fast
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