Compaq Computer Corporation, Inc.

Richard E Walker

Thanh Thien Tran

Richard A Faulk

Hai Ngoc Nguyen

Kurtis J Bowman

Tranh T Tran

The present invention relates to a variable voltage regulator that can be easily adjusted via a jumper, or a signal (provided by another circuit) so that the variable voltage regulator can provide at least one of a plurality of discrete voltages to an integrated circuit, such as a microprocessor. This is useful when a replacement microprocessor requires a different operating voltage than the microprocessor it replaced.

Variable voltage regulator system

A circuit that automatically switches the power supply voltage PVDD provided to a CPU between 3.3 volts and 5 volts. The circuit detects whether the CPU installed in a socket is a 3.3-volt part or a 5-volt part by determining the state of a voltage detect sense pin provided by the socket. If the voltage detect sense pin is driven low, that indicates a 3.3-volt CPU is being used. If a 5-volt CPU is installed, the voltage detect sense pin is left floating by the CPU, which allows a pullup resistor to pull the voltage detect sense pin high. The power supply voltage provided to the CPU is regulated through a power field effect transistor (FET). The gate of the power FET is connected to the output of a voltage reference source and is coupled to a 12-volt supply signal. If the voltage detect sense pin is pulled high, the voltage reference source is turned off, allowing the 12-volt supply signal to drive the gate of the power FET. This in turn allows the power FET to pass a 5-volt supply signal to the CPU supply signal PVDD. If the voltage detect sense pin is pulled low, the voltage reference source is turned on to drive the gate of the power FET to approximately one threshold voltage above 3.3 volts. In response, the power FET passes only 3.3 volts to the CPU supply signal PVDD.

Circuit that automatically switches between supplying a microprocessor

An efficient fan drive circuit to drive a variable fan used in a power supply of a personal computer system. The fan drive circuit uses a diode to establish the minimum fan speed during operation in the normal temperature range. The bleeder resistor normally coupled between the fan and a negative output voltage is removed and replaced with a current source. The current source also serves to shut down the power supply if the fan is not operating properly or is not installed. A shut down circuit remains to shut down the power supply when excessive temperature occurs, or when the current source detects that the fan is malfunctioning or not installed.

Low power fan drive circuit for personal computers

A computer system has a monitor which can be powered down to conserve electrical power. The Monitor has two power modes, normal power mode and low power mode. Upon receiving a signal from the CPU, the monitor switches between power modes.

Computer system with power-down mode for monitor

A power supply monitoring circuit, and a data processing system incorporating the same together with a regulated power supply and system components such as a CPU, are disclosed. The power supply monitoring circuit includes delay circuits, with the respective delays selected by the selection of capacitor values, for delaying the issuing of a 'power-good' signal to the CPU after power-up until sufficient time has passed after establishment of adequate voltages on the power supply bus to allow the power supplies to stabilize, and for ignoring undervoltage faults (in generating a power supply shutdown signal) on said power supplies for a brief period of time after power-up. The stabilization and power-up delay periods may be selected independently from one another, so that the power-up delay can expire prior to the expiration of the stabilization delay. In this way, the power supply can be promptly turned off if an undervoltage condition is present during power-up, reducing the risk of component damage from absence of adequate power supply voltages.

Power supply supervisor with independent power-up delays and a system

A low conductivity mounting stud for attaching an electronic component to a base structure such as a heat sink eliminates the need for several insulating washers and other insulators around the shaft of the mounting stud. The mounting stud may be composed of ceramic material such as partially stabilized zirconia. The mounting stud is secured with a press-on fastener such as a 'Tinnerman nut'.

Low conductivity mounting stud and a method and apparatus for fastening

A computer system having a power supply monitoring arrangement employs a number of comparators for detecting whether or not various supply voltages produced by the power supply for use in the computer are above or below a reference level, or whether an overcurrent condition exists. These detected conditions are used to determine whether or not the power supply should be shut down, or during power-up to determine whether the initialization routine can be started by the CPU. Delays are included to prevent an undervoltage condition from indicating shut down of the power supply during power-up.

Growing community of inventors

The Woodlands, TX, United States of America

Richard E Walker