公开(公告)号：AT478388T

公开(公告)日：2010-09-15

申请号：AT08730948

申请日：2008-02-28

Applicant: MICROCHIP TECH INC

Inventor： BUTLER DANIEL ,  DARMAWASKITA HARTONO

IPC: G06F13/40

Abstract: A low power Universal Serial Bus (USB) capable device uses a weak pull-up resistance that is coupled to at least one data line of the USB for detection of when the USB capable device is connected to a USB host or hub. When the USB capable device is not connected to the USB host or hub, USB peripheral, including the USB transceiver, USB voltage regulator, serial interface and/or USB logic circuits required for USB operation may be powered down to conserve power drawn by the USB capable device. When the USB capable device is connected to the USB host or hub, a voltage from the weak pull-up will be significantly reduced, thus signaling that the USB peripheral and associated circuits should be powered up for normal USB operation.

公开(公告)号：DE602008002223D1

公开(公告)日：2010-09-30

申请号：DE602008002223

申请日：2008-02-28

Applicant: MICROCHIP TECH INC

Inventor： BUTLER DANIEL ,  DARMAWASKITA HARTONO

IPC: G06F13/40

公开(公告)号：AT384291T

公开(公告)日：2008-02-15

申请号：AT05754513

申请日：2005-05-26

Applicant: MICROCHIP TECH INC

Inventor： JULICHER JOSEPH ,  OTTEN DAVID ,  BUTLER DANIEL

IPC: G06F1/08 ,  G06F1/26 ,  H03L7/06

Abstract: Clock speed is controlled based upon the supply voltage to a digital device. When the supply voltage is below a reference voltage the clock speed will be slower than if the supply voltage is above the reference voltage. A phase-lock-loop (PLL) may be used to generate a higher frequency that is an integer multiple of a reference oscillator. The clock speed will be proportional to the frequency multiplication of the PLL when the faster clock speed is selected. A multiplexer is used to switch between different frequency sources, and a timer can be used to insure stable operation of the PLL. A status configuration register has status and control bits for indicating and controlling operation of the clock speed control. A universal serial bus (USB) device can operate at a slower clock with reduced operating voltage, and at a faster clock with increased operating voltage.