MAX4889 Maxim, MAX4889 Datasheet - Page 11

• Manufacturer Part Number: MAX4889
• Description: The MAX4888/MAX4889 high-speed passive switches route PCI Express® (PCIe) data between two possible destinations
• Manufacturer: Maxim

The MAX4888/MAX4889 primary applications are aimed
at reallocating PCIe lanes (see Figure 5). For example,
in graphics applications, several manufacturers have
found that it is possible to improve performance by a
factor of nearly two by splitting a single 16-lane PCIe
bus into two 8-lane buses. Two of the more prominent
examples are SLI™ (Scaled Link Interface) and
CrossFire™. The MAX4889 permits a computer mother-
board to operate properly with a single 16-lane graph-
ics card, and can later be updated to dual cards. The
same motherboard can be used with dual cards where
the user sets a jumper or a bit through software to
switch between single- or dual-card operation.
High-speed switches require proper layout and design
procedures for optimum performance. Keep design-
controlled impedance PCB traces as short as possible
or follow impedance layouts per the PCIe specification.
Ensure that power-supply bypass capacitors are
placed as close to the device as possible. Multiple
bypass capacitors are recommended. Connect all
grounds and the exposed pad to large ground planes.
CrossFire is a trademark of ATI Technologies, Inc.
SLI is a trademark of NVIDIA Corporation.
Applications Information
______________________________________________________________________________________
2.5Gbps PCI Express Passive Switches
PCIe Switching
Board Layout
Figure 5. The MAX4888/MAX4889 Used as a Single-Lane
Switch
PROCESS: CMOS
ONE LANE
NOTE: ONLY ONE LANE IS SHOWN FOR CLARITY
MAX4888
MAX4889
Chip Information
A
DATA IS ROUTED
BOARD A OR B
DIRECTION
TO EITHER
DATA
B
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