Chapter 1
Overview
System Backplane
17
System Backplane
There are two backplane boards: the HLSB (Left Backplane) and the HRSB (Right Backplane). For a
single-cabinet system the determination is not relevant, but in a two-cabinet system it is. Whether a system
has either a left or right backplane depends on the location of the system in an SD64 complex. Each
backplane has a “flex” connection on one side or the other. The flex interconnect allows connecting two
cabinets across a crossbar link. In order to create a two cabinet system using this flex interconnect, one
cabinet must contain a HLSB and the other must contain a HRSB. The Flex goes between the two
backplanes. The backplane supports eight cell boards and has four crossbar ASICs. It contains clock circuits,
Local Power Monitor (LPM), link exploration logic, and various JTAG and reset logic devices. It is not hot
swappable as the system power must be removed to replace a backplane.
The backplane also contains three Backplane Power Boards (HBPB) per backplane that are located on the
opposite side from the cell boards. There is a maximum of three HBPBs per backplane. The HBPB supplies
N+1 (N=2) redundant +1.8 V power and N+2 (N=1) redundant +3.3 V power. Each HBPB contains a
DC-to-DC brick converter for each of these voltages. These converters support current sharing with the other
HBPBs in the system. They are accessible from the rear of the cabinet and are hot swappable.
NOTE When hot swapping a failed HBPB, some Superdome systems upgraded to an either an hp
Integrity Superdome or an hp 9000 Superdome system could lose 48V and power down the
complex. If the system backplane has a engineering date code of 4310 or greater the possibility
does not exist.
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