Power for change

The key power assembly in MicroTCA systems is the MicroTCA power module which, by its own definition, has to deliver and secure the power required by Advanced Mezzanine Cards (AMC) and other accessories that plug into the MicroTCA enclosure. The MicroTCA power module (MPM), which contains most of the power conversion and control circuitry, eliminates the need for the large planar carrier boards required in AdvancedTCA systems. The module includes power filtering, dc/dc conversion and power management functions. DC input power is provided via connectors on the front panel, while 12V and 3.3V payload and management power is connected to the MicroTCA backplane. MPMs provide payload and management power for all loads in the MicroTCA enclosure, which may include two cooling units and two shelf level MicroTCA Carrier Hubs in addition to the maximum of 12 AMC modules – a maximum of 16 ‘channels’ of output power. Meeting MicroTCA specifications and consolidating power handling circuitry and system level control/management functionality requires highly integrated power conversion modules. On top of converting the system 48V to an intermediate 12V with high efficiency, the modules must communicate with the rest of the system through the Enhanced Module Management Controller (EMMC). The MicroTCA specification includes provision for redundant power modules to increase system availability. When needed, this capability can function quite well and achieve system availability goals. It is important to understand, however, that power modules designed for redundant operation are more complex and more costly than those intended for standalone operation. The required output voltage tolerance on the 12V payload output depends on whether redundancy is used in the MicroTCA system. To guarantee the highest flexibility, Ericsson decided to consider all options built in one unit, which puts a higher demand on the internal dc/dc converter. The basic MicroTCA specification defines the tolerance range for the AMC module input voltage as 10 to 14V. Since the load module will operate at any voltage in this range, the 12V dc/dc converter could have a ±10% tolerance in a non redundant system.