Specifications

QSSC-S4R Technical Product Specification SAS Riser
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Figure 21. SAS Riser Board Placement View
The sideband signals are configured to adhere to the SFF-8485 and SFF-8448 specifications. This dual sideband
functionality allows the Hot-swap Backplane (HSBP) to determine the enclosure management type: either I2C or
SGPIO.
7.2.4 Memory Interface
The SAS Riser board supports a single bank of on-board DDR2 ECC memory at a speed of 800MHz. It supports a five
chip, 72 bit memory configuration, made up of 64Mx16 devices for a total of 512 MB addressable DRAM Memory. This
memory is capable of being powered via the iBBU connector when the main board power is absent to allow for memory
retention in the event of a power failure.
7.2.5 Debug Jumpers
Two debug jumpers (JT10 – “BRK” and JT9 – “BRD DFLT”, as shown in Figure 21. SAS Riser Board Placement View)
allow for loading some basic configurations and prevent the firmware from fully executing. Installing the “BRK” jumper
will prevent the BIOS code from executing. The “BRK” jumper is connected to the GPIO(2) pin on the SAS2108.
Installing the “BRD DFLT” jumper will cause the LSI SAS2108 to power up using default configuration values and not
read the SBR SEEPROM. The “BRD DFLT” jumper is connected to the SYS_SDATA(0) pin on the SAS2108.
7.2.6 iBBU07 Remote Battery Backup for On-board Memory (optional)
The option for providing battery power to the memory cache during a power failure is available on this board via a
remote converter module (JT3, as shown in Figure 21. SAS Riser Board Placement View) connecting iBBU07 battery
backup unit, which is installed on the dedicated location on the chassis side wall utilizing the BBU holder. Lithium Ion
battery technology is used on the iBBU07. This connection to the iBBU07 via the remote converter module contains
signals including power, control, status, and I2C.
7.2.7 SAS Riser Power
The main board supplies 12V, 3.3V, and 3.3V_STBY power to the SAS riser via the standard PCI-Express interface.
The PCI-Express specification requires that the 12V rail and the 3.3V rail have a voltage tolerance of 8% and 9%
respectively. The amount of power that an adapter card can use is also limited. The overall power limit is 25W. The
maximum current draw allowed on the 3.3V rail is 3A and for the 12V rail is 2.1A. The SAS2108 has a tolerance
specification of +/-5% on the 3.3V rail which is tighter that the PCI Express supplied 3.3V rail. For this reason the 3.3V,
1.8V, 0.9V VTT plane, 1.0 V, and PowerPC voltages are all regulated on board to utilize the allowed voltage and
current.