EPENTIUM® PROCESSOR WITH VOLTAGE REDUCTION TECHNOLOGY
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7.1.3.1. Power Sequencing
There is no specific sequence required for powering
up or powering down the VCC2 and VCC3 power
supplies. However, for compatibility with future
mobile processors, it is recommended that the VCC2
and VCC3 power supplies be either both on or both
off within one second of each other.
7.1.4. AC Specifications
The AC specifications of the SPGA Pentium
processor with voltage reduction technology consist
of setup times, hold times, and valid delays at 0 pF.
All SPGA Pentium processor with voltage reduction
technology AC specifications are valid for VCC2 =
2.9V + 165mV, VCC3 = 3.3V + 165mV, and TCASE = 0
to 85ºC.
WARNING
Do not exceed the 75-MHz Pentium processor
with voltage reduction technology internal
maximum frequency of 75 MHz by either
selecting the 1/2 bus fraction or providing a
clock greater than 50 MHz.
Do not exceed the 90-MHz Pentium processor
with voltage reduction technology internal
maximum frequency of 90 MHz by either
selecting the 1/2 bus fraction or providing a
clock greater than 60 MHz.
7.1.4.1. Power and Ground
For clean on-chip power distribution, the SPGA
Pentium processor with voltage reduction technology
has 25 VCC2 (2.9V power), 28 VCC3 (3.3V power)
and 53 VSS (ground) inputs. Power and ground
connections must be made to all external VCC2, VCC3
and VSS pins of the SPGA Pentium processor with
voltage reduction technology. On the circuit board all
VCC2 pins must be connected to a 2.9V VCC2 plane
(or island) and all VCC3 pins must be connected to a
3.3V VCC3 plane. All VSS pins must be connected to
a VSS plane. Refer to Table 36 for a listing of VCC2
and VCC3.
7.1.4.2. Decoupling Recommendations
Transient power surges can occur as the processor
is executing instruction sequences or driving large
loads. To mitigate these high frequency transients,
liberal high frequency decoupling capacitors should
be placed near the processor.
Low inductance capacitors and interconnects are
recommended for best high frequency electrical
performance. Inductance can be reduced by
shortening circuit board traces between the
processor and decoupling capacitors as much as
possible.
These capacitors should be evenly distributed
around each component on the 3.3V plane and the
2.9V plane (or island). Capacitor values should be
chosen to ensure they eliminate both low and high
frequency noise components.
Power transients also occur as the processor rapidly
transitions from a low level of power consumption to
a much higher level (or high to low power). A typical
example would be entering or exiting the Stop Grant
state. Another example would be executing a HALT
instruction, causing the processor to enter the Auto
HALT Powerdown state, or transitioning from HALT
to the Normal state. All of these examples may cause
abrupt changes in the power being consumed by the
processor. Note that the Auto HALT Powerdown
feature is always enabled even when other power
management features are not implemented.
Bulk storage capacitors with a low ESR (Effective
Series Resistance) in the 10 to 100 µf range are
required to maintain a regulated supply voltage
during the interval between the time the current load
changes and the point that the regulated power
supply output can react to the change in load. In
order to reduce the ESR, it may be necessary to
place several bulk storage capacitors in parallel.
These capacitors should be placed near the
processor (on the 3.3V plane and the 2.9V plane (or
island)) to ensure that these supply voltages stay
within specified limits during changes in the supply
current during operation.
For more detailed informations, please contact Intel
or refer to the
Pentium
Processor with Voltage
Reduction Technology: Power Supply Design
Considerations for Mobile Systems
application note
(Order Number 242558).
7.1.4.3. Connection Specifications
All NC pins must remain unconnected. Refer to Table
36 for a listing of NC pins.
All RESERVED pins must remain unconnected.