A80960HA25SL2GX INTEL [Intel Corporation], A80960HA25SL2GX Datasheet - Page 36

• Manufacturer Part Number: A80960HA25SL2GX
• Description: 80960HA/HD/HT 32-Bit High-Performance Superscalar Processor
• Manufacturer: INTEL [Intel Corporation]

80960HA/HD/HT
4.3
4.4
30
Figure 7. VCC5 Current-Limiting Resistor
Table 20. V
Recommended Connections
Power and ground connections must be made to multiple V
80960Hx-based circuit board should include power (V
distribution. Every V
the ground plane. Pins identified as “NC” —no connect pins—must not be connected in the system.
Liberal decoupling capacitance should be placed near the 80960Hx. The processor can cause transient
power surges when its output buffers transition, particularly when connected to large capacitive loads.
Low inductance capacitors and interconnects are recommended for best high-frequency electrical
performance. Inductance can be reduced by shortening the board traces between the processor and
decoupling capacitors as much as possible. Capacitors specifically designed for PGA packages
offer the lowest possible inductance.
For reliable operation, always connect unused inputs to an appropriate signal level. In particular,
any unused interrupt (XINT7:0, NMI) input should be connected to V
as should BTERM if not used. Pull-up resistors should be in the range of 20 K for each pin tied
high. If READY or HOLD are not used, the unused input should be connected to ground. N.C. pins
must always remain unconnected.
VCC5 Pin Requirements (V
In mixed-voltage systems that drive 80960Hx processor inputs in excess of 3.3 V, the VCC5 pin must
be connected to the system’s 5 V supply. To limit current flow into the VCC5 pin, there is a limit to
the voltage differential between the VCC5 pin and the other V
between the 80960Hx VCC5 pin and its 3.3 V V
applies to power-up, power-down, and steady-state operation.
Meeting this requirement ensures proper operation and guarantees that the current draw into the
VCC5 pin does not exceed the I
If the voltage difference requirements cannot be met due to system design limitations, an alternate
solution may be employed. As shown in
to limit the current into the VCC5 pin. This resistor ensures that current drawn by the VCC5 pin
does not exceed the maximum rating for this pin.
This resistor is not necessary in systems that can guarantee the V
In 3.3 V-only systems and systems that drive 80960Hx pins from 3.3 V logic, connect the VCC5
pin directly to the 3.3 V V
V
DIFF
Sym
DIFF
Specification for Dual Power Supply Requirements (3.3 V, 5 V)
VCC5-V
Difference
Parameter
CC
CC
Min
pin must be connected to the power plane; every V
CC
Max
2.25
plane.
+5 V (±0.25 V)
CC5
Units
specification.
V
Figure
VCC5 input should not exceed V
power-up and power-down, or during steady-state operation.
DIFF
(±5%, 0.5 W)
CC
7, a minimum of 100
100
)
pins should never exceed 2.25 V. This limit
CC
) and ground (V
VCC5 Pin
CC
Advance Information
and V
Table 20
CC
pins. The voltage differential
DIFF
SS
Notes
(GND) pins. Every
CC
outlines this requirement.
specification.
CC
SS
series resistor may be used
SS
through a pull-up resistor,
) planes for power
by more than 2.25 V during
pin must be connected to
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