Power management system for integrated circuits

摘要

A system for controlling the application of power by a power supply to a load. The inventive system includes a first circuit for drawing power from the power supply and a second circuit for controlling the amount of power drawn by the first circuit from the power supply. The amount of power drawn from the power supply is gradually increased prior to the application of power to the load and gradually decreased after removal of power from the load. In the illustrative embodiment, the first circuit is a digitally controlled resistance and the second circuit is a digital counter which supplies a control word for the digitally controlled resistance. A high order bit from the counter enables the gating of clock pulses to the load circuit. As a result, activation of the load circuit is delayed while the invention gradually varies the amount of power drawn from the power supply to a desired threshold level. The gradual draw of power from the supply significantly mitigates transients ordinarily associated with the application of clock pulses to a load circuit at machine startup or removal of clock pulses at machine shutdown.