Future Trends in Power Management
As the features, complexity and capabilities of electronics systems have evolved over time, so have the requirements for power management in these systems. Evolving from board-level power generation to system-wide power management, and now to system management, the technology for addressing power concerns in electronic systems has increased in complexity along with the systems they supply.
Power generation in early electronic systems involved discrete components, providing simple voltage levels that were either on or off. As the number of devices on a board and their complexity increased, boards ended up with multiple supply voltages and as a result, needed sequencing between the different levels. This type of system would use either an application-specific standard product (ASSP) or simple programmable logic power management device. These devices are configured when the system is created and continue with the same function regardless of system response.
Intelligent power management not only controls the voltages, but can also track and trim the voltages and currents in a closed-loop monitoring system. This requires more intelligence than the basic programmable power devices. The intelligence can be provided either in the form of a microprocessor or FPGA beside the power management devices. For example, Actel’s low-power IGLOO devices can be used to store a start-up sequence for the system while using very little power, providing the capability to enter shutdown mode or low frequency operating mode to maintain minimum function while waiting for a wake-up signal to trigger the rest of the sequence.
System management is the next step in the evolution of power management. System management requires more than just voltage generation and sequencing; it includes system knowledge and communication between multiple boards to manage voltage, current, and temperature for the complete system. System management can be implemented using either custom design or developed with emerging standards-based options.
The Intelligent Platform Management Interface (IPMI) message-based interface is widely used in system management implementations for platform monitoring and control functions. Management resources, either on board or remotely located, can track the status and voltage usage of all the boards across multiple systems. For example, IPMI enables a power-down request to be sent to one board in the system. That board then communicates back that it is either unable to power-down because it is in the middle of some critical action, or it is able to execute the power-down request and is doing so now. IPMI communication is not all one way; a managed board can also send a critical status message up to the management resource, indicating a critical payload fault, out of thermal range, voltage or current conditions, or routine sensor log readings. AdvancedTCA, AdvancedMC, and MicroTCA are examples of standards that use IPMI for communication between managed boards, often collectively referred to as TCA standards.
As more systems incorporate integrated system management, these implementations will eventually grow to include predictive diagnostics and enhanced sensor data logging capabilities to enable continuous system monitoring, managed maintenance and dynamic system resources, and power optimization based on tracking of system parameters in real time.
Today, FPGA logic can be used to implement communications protocols that can request a service call while the flash memory blocks perform data logging and tracking. In the future, these same sensor records and communication protocols will enable identification of sensor readout patterns that pinpoint a system module that will soon fail. Requesting pre-emptive replacement before modules fail will result in significant improvements in system up-time and reliability.
Better monitoring of system power and tighter control of when sections of the system are powered up can lead to a reduction in power usage and reliability of complex electronic systems. By using a single-chip, high-reliability, mixed-signal flash FPGA solution, design engineers can now take advantage of the full range of system management capabilities.
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This article first appeared in the January, 2009 issue of Portable Design. Reprinted with permission.