Universal Serial Bus Current Limit
AssigneeResearch In Motion Limited
InventorsMarc A. Drader, David James Mak-Fan, Dusan Veselic
Life of this patent
Estimating the term…
Abstract
A load device includes a power input having an interface to a power supply; a peripheral power bus including an internal capacitance, and an active switch coupled to the power input and the peripheral power bus for applying power from the power input to the peripheral power bus. The load device also includes a switch controller coupled to the active switch for regulating the in-rush current drawn by the internal capacitance through the active switch while the internal capacitance is being charged.
Claims19
A load device, comprising:
- a system power bus having a universal serial bus (USB) interface;
- a peripheral power bus;
- an active switch coupled to the system power bus and the peripheral power bus for applying power from the system power bus to the peripheral power bus and for controlling a plurality of operation intervals of the active switch;
- and
- a switch controller coupled to the active switch, the switch controller cyclically opening and closing the active switch by applying a periodic gate signal during a first operational interval of the plurality of operational intervals, the periodic gate signal comprising a plurality of pulses, so as to limit the current drawn by the peripheral power bus to be within USB standard limits, and the switch controller maintaining the active switch fully on during a second operational interval of the plurality of operational intervals.
In a load comprising a system power bus having a universal serial bus (USB) interface, a peripheral power bus, and an active switch for applying power from the system power bus to the peripheral power bus and for controlling a plurality of operational intervals of the active switch, a method comprising:
- applying a periodic gate signal to the active switch input, the periodic gate signal determined to cyclically open and close the active switch during a first operational interval of the plurality of operational intervals, the periodic gate signal comprising a plurality of pulses, so as to limit the current drawn to be within USB standard limits, and
- maintaining the active switch fully on during a second operational interval of the plurality of intervals.
A computer-readable medium including computer processing instructions for a processing unit of a portable computing device, the portable computing device comprising a system power bus having a universal serial bus (USB) interface, a peripheral power bus, and an active switch coupled to the system power bus and the peripheral power bus for applying power from the system power bus to the peripheral power bus and for controlling a plurality of operational intervals of the active switch, the computer processing instructions when executed by the processing unit causing the portable computing device to:
- cyclically open and close the active switch during a first operational interval of the plurality of intervals by applying a periodic gate signal , the periodic gate signal comprising a plurality of pulses, all of the pulses having substantially identical pulse-width, to limit the current drawn by the peripheral power bus to be within USB standard limits, and
- maintain the active switch fully on during a second operational interval of the plurality of operational intervals.
Dependencies are inferred from the claim text.