GT-64260A Design Guide
Doc. No. MV-S300165-00, Rev. A
CONFIDENTIAL
Copyright © 2002 Marvell
Page 140
Document Classification: Proprietary Information
May 21, 2002, Preliminary
Section 18. Power Supply
The GT-64260A uses low-core voltages to attain higher operating speeds and lower power consumption.
It also divides the I/O power pins of various signals into logical groups. Each group may be set to different volt-
ages. This allows the use of lower-voltage (faster) processor buses. This allows clamping PCI signals to 5V if
required (dictated by the PCI bus), 5V tolerance for some interfaces, and 2.5V/3.3V IO voltage support for the
CPU interface.
describes the various GT-64260A voltages.
Note
For more information on the PLL power supply filtering, see the GT-64260A datasheet’s "PLL Power Filter
Circuit" section.
All power planes must be de-coupled to ground to provide for reasonable management of the switching currents (
d
I/
d t
) to which the plane and its supply path are subjected. This is platform dependent and not detailed in the spec-
ification in a manner consistent with high speed signaling techniques.
18.1 De-coupling Recommendations
Due to large address and data buses and high operating frequencies, the GT-64260A can generate transient
power surges and high frequency noise in its power supply, especially while driving large capacitive loads. This
noise must be prevented from reaching other components in the GT-64260A system.
To avoid noise affecting other components, ensure that there is sufficient capacitance in the power distribution
system to supply the current and support voltage.
Table 32:
GT-64260A Voltages
Power
Group
Function
No. of
Pins
Nominal
Voltage
Notes
V
CC
2.5V
I/O Supply Voltage
10
3.3V or 2.5V
CPU interface
V
CC
3.3V
I/O Supply Voltage
33
3.3V
SDRAM, Communication,
PCI and device interfaces
V
CC
core
Core Supply Voltage
11
1.8V
VREF
PCI Clamp Voltage
2
3.3V or 5V
AVCC
PLL filtered power
1
1.8
Separate filters required
AGND
PLL filtered ground
1
GND
Separate filters required
GND
Ground, common
58
GND