1.9
Power Supplies, Sequencing, and De-Coupling
The switch’s maximum power consumption is approximately 6W. Special cooling requirements may exist,
depending upon the system environment. (Refer to the
PEX 8632 Data Book
for details.)
1.9.1
Power Supplies
The PEX 8632 has the following Power ball groups:
VDD10 – Digital core logic supply
VDD10A – SerDes analog supply
VDD25 – Hot Plug, serial EEPROM, I
2
C, JTAG, Port Status indicators, I/O buffers
VDD25A – PEX_REFCLK PLL supply
At the board level, VDD10 and VDD10A can share a common 1.0V ±5% power plane, and VDD25 and
VDD25A can share a common 2.5V power plane. The current demands for these supplies can be high,
depending upon the device (approximately 80 mA per Lane, plus 32 mA); therefore, ensure that the
power plane is sufficiently sized, to support the specified operating current. For best performance,
the 1.0V ±5% plane should have an adjacent ground plane that provides an interplane capacitor to supply
high-frequency transient currents. Provide a sufficient number of discrete capacitors for mid- and
low-frequency de-coupling. The recommendation is that 0201-sized capacsitors be used in close
proximity to these power balls, as illustrated in
.
VDD10A
VDD10
GND
1000 pF 0201
A1
Figure 11. Power Balls and Capacitor Placement
PEX 8632-AA Quick Start Hardware Design Guide, Version 1.1
© 2007 PLX Technology, Inc. All Rights Reserved.
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