UNIVERSAL SERIAL BUS CURRENT LIMIT

摘要

A load device includes an interface to a universal serial bus, a system bus coupled to the universal serial bus interface for powering electronic circuitry of the load device, a peripheral bus coupled to the universal serial bus interface, and an active switch coupled to the universal serial bus interface and the peripheral bus for applying power to the peripheral bus. The peripheral bus includes an internal capacitance, and the active switch has a switch input for controlling an operational interval of the active switch. The load device also includes a switch controller coupled to the active switch. The switch controller is configured to regulate the in-rush current drawn by the intern al capacitance by applying a pulse train to the switch input. The pulse train is predetermined to maintain the instantaneous voltage at the system bus above a predetermined lower limit.