Hewlett-packard Development Company, L.P.

Compaq Computer Corporation, Inc.

George Farris Squibb

George A Kaminski

Mark R Trace

Robert C Brooks

Robert S Wright

Joseph A Clegg

A system comprises an AC/DC adapter having a connector. The system also comprises a portable computer that receives said connector. The portable computer comprising a delay circuit coupled to a power transistor that is coupled in parallel with a resistor. The delay circuit causes the power transistor to activate following a time delay after current from the adapter begins to flow through the resistor. As a result of a user beginning to remove the connector from the portable computer, a control transistor is activated to reset the delay circuit.

Delay circuit with reset feature

In one embodiment, a fan control system includes a temperature-sensing device that is adapted to sense a temperature of a component and output a temperature feedback signal, and a pulse width modulation control circuit that is configured to receive the temperature feedback signal output from the temperature-sensing device and a separate fan command signal and, relative to those signals, generate a pulse width modulation signal that is sent to a pulse width modulation controlled fan.

Pulse width modulation fan control

A method and related structure for reducing the harmonic distortion on an input signal line of a switching power supply accomplished by a first or upstream power supply adjusting the input voltage such that the duty cycle of conduction or switching signals applied to each phase of a switching power supply have no significant overlap or gap.

System and method for adjusting an input voltage to a switching power supply while keeping the output voltage constant

A method and system for controlling the power supply fan in a computer system. The speed of a power supply fan can be made directly proportional to the temperature of the power supply. The fan speed can also be controlled by a processor with software commands according to the temperature of the processor. The speed of the fan will be dictated by the higher of the two commands driving it. Therefore, the power supply fan can never be commanded by the processor to run at a lower speed than that required by its own thermal environment. A Fan Speed Control Circuit enables the computer system to command the power supply fan to run at a higher speed. The processor temperature can be monitored with a temperature transducer and analog signal conditioning circuitry.

Dual control of fan speed-input corresponding to power supply temperature or software command from the processor corresponding to processor temperature

Dual power supply fan control&mdash;thermistor input or software command from the processor

A circuit and method for controlling current drawn from two different voltage sources while maintaining regulation of a fixed output voltage during controlled switching of different sleep states required by the microprocessor and system board.

Selective dual input low dropout linear regulator

A power switch circuit including a small signal transformer and a low power oscillator for detecting the power switch while isolating it from the primary of the power supply. When the power switch is off, or is otherwise pressed to turn off the power supply, the oscillator charges a capacitor. A sensing and control circuit coupled to the oscillator and capacitor grounds a vital signal of the power supply keeping the power supply turned off. In one embodiment, when the switch is turned on, it shorts the signal transformer disabling the oscillator, so that the capacitor is discharged and the sensing and control circuit releases the vital signal. In another embodiment, the power switch momentarily disables the oscillator and discharges the capacitor, so that the sensing and control circuit toggles a flip-flop circuit to turn on the power supply.

Growing community of inventors

Spring, TX, United States of America

George Farris Squibb