Pre-energized auxiliary circuits for very fast transient loads: Coping with load-informed power management for computer loads

The recent development in computer science that the power demand and required time of code execution can be accurately predicted is paving a path that may lead to a new paradigm shift in power supply design. Specifically, while the design of power supplies now normally assumes that load current changes at random times and with unknown magnitudes (within a range), future computer loads may communicate with power supplies to provide information that facilitates power management. Such information would include the exact times of occurrence of load transients and their magnitudes. Following this trend of development where the power supply is 'informed' by the load, we propose to use an auxiliary circuit that generates a slowly rising current prior to the occurrence of the actual transient. The slowly rising current can cause the power supply to shift its operation point to a new level slowly without exhibiting output voltage fluctuation. The actual load exhibits very fast current transient, but the combination of actual load and auxiliary circuit behaves as a slowly changing load which can be dealt with by an ordinary power supply capable of handling slowly changing load current. Thus, this method essentially buffers the power supply from large and fast transients. Our proposed approach involves the necessary algorithm for controlling the auxiliary circuit in accordance with the information provided by the microprocessor. The design of the auxiliary circuit is explained and experimental results for a 1.5 V load with 15 A step current are provided for verification.