Filter
Top Products
MPCMM0002 CMM—Module Components
Intel NetStructure
®
MPCMM0002 Chassis Management Module
Hardware TPS July 2007
22 Order Number: 309247-004US
4.13.2 Dual Bus IPMB Isolation Requirements
The isolation requirements for a dual bus IPMB are more stringent. In addition to the
power failure isolation needed by radial IPMBs, dual bus IPMBs must be able to
selectively enable and disable the isolation on each bus. Furthermore, each element on
the bus must protect against errors that can cause the bus to hang. Finally, there are
electrical drive and rise time requirements that are more difficult to meet on a shared
bus.
An LTC4300 on each bus provides the necessary individually selectable isolation
mechanisms in addition to rise time acceleration. A watchdog timer is also used to
ensure the bus is isolated if the CPU locks up and resets so that glitches are not
propagated to other controllers on the bus. See Figure 6.
Figure 5. IPMB Dual Star Isolation
SLOT a
or
CDM a
FPGA 1
IPMBb
IPMBa
IPMB_PWRGOOD
IPMB_PWR
FPGA 2
IPMBb
CMM 1
IPMB_PWRGOOD
IPMB_PWR
FPGA 1
IPMBb
IPMBa
IPMB_PWRGOOD
IPMB_PWR
FPGA 2
IPMBb
CMM 2
IPMB_PWRGOOD
IPMB_PWR
SLOT b
or
CDM b