10 ADM1026 Controller, Hot Swap Controller

Module Components—MPCMM0002 CMM

4.10ADM1026 Controller

An Analog Devices* ADM1026 controller monitors the on-board voltages and manages the thermal sensors. The processor communicates with the ADM1026 through an I2C bus.

4.11Hot Swap Controller

The CMM uses an LTC4250AH* Hot Swap controller to ramp voltages and watch for over-current conditions. If the CMM draws more than 2.5 A for more than 500 µs, the Hot Swap controller terminates.

The Hot Swap controller waits for the enable signals (short pins tied to each return) to connect before ramping up the circuitry on the CMM. Similarly, if a CMM is pulled out of the system, the Hot Swap controller immediately cuts power to the board.

4.12Ride-Through Support

Many carriers require equipment to survive a 5 ms period without any power in order to survive power glitches due to short circuit, power switchovers, etc. Section 4.1.4.3 of the PICMG 3.0 specification requires boards to survive this 5 ms drop-out and recommends that other chassis elements also have capability to ride through these transients.

The MPCMM0002 CMM module meets this requirement. The CMM will survive the zero volt transient described in Table 4-4 of the PICMG 3.0 specification. Large bulk capacitors next to the DC-DC power converters provide this hold-up capacity.

4.13IPMB Isolation Logic

In a carrier-grade system it is important to prevent cascaded failures; that is, a failure in one element that affects other system elements and causes them to fail or lose significant functionality. A shared bus is more sensitive to a single item impacting other elements than a simple point-to-point system. This is one reason the MPCMM0002 CMM chassis management module implements the hybrid dual IPMB star topology outlined in Section 6.1, “IPMB Routing” on page 28.

Some IPMB channels are dedicated links between the CMMs and an individual blade; this type of link is called a star. Some IPMB channels are shared among several devices, and this type of link is called a bus. The star and bus elements have different isolation logic in the CMM.

4.13.1Dual Star IPMB Isolation

The dual star IPMBs on the MPCMM0002 CMM use MOSFET-controlled isolators to disconnect all the radial IPMB signals automatically if power fails on a CMM. The isolation circuit is pictured in Figure 5. The hardware ensures that the CMM is isolated from the dual star IPMBs if power fails.

	Intel NetStructure® MPCMM0002 Chassis Management Module
July 2007	Hardware TPS
Order Number: 309247-004US	21