Abstract: An input protection circuit (IPC) may prevent an input signal from propagating into a system, such as an integrated circuit (IC), when the voltage level of the input signal exceeds a specified value. The IPC may be configured to compare the input signal voltage, which may be that of an external input signal received by the system, with a reference voltage, which may be the power supply voltage. If the input signal voltage exceeds the reference voltage, the output of the IPC may be set to the value of a specified clamp voltage. If the input signal voltage does not exceed the reference voltage, the output of the IPC may track (or follow) the input signal voltage. For certain integrated circuits, the IPC may be configured to provide circuit protection for an input signal voltage ranging between 0V to 5V, and a power supply voltage ranging between 3.0V and 3.6V.

Abstract: A method and apparatus for operating a portable computer configured for docking to a docking station is disclosed. In one embodiment, a portable computer system includes a docking interface having a bus switch and a bus monitoring circuit, and a bus coupled to the docking interface. With the computer coupled to a docking station, the bus switch, when closed, may couple the bus to a peripheral interface in the docking station. The bus switch may close responsive to docking, thereby completing the electrical coupling of the bus to the peripheral interface in the docking station. The portable computer being docked to the docking station, the bus monitoring circuit may monitor the bus cycles occurring on the bus and identify trusted read and/or write cycles.

Abstract: An input protection circuit (IPC) may prevent an input signal from propagating into a system, such as an integrated circuit (IC), when the voltage level of the input signal exceeds a specified value. The IPC may be configured to compare the input signal voltage, which may be that of an external input signal received by the system, with a reference voltage, which may be the power supply voltage. If the input signal voltage exceeds the reference voltage, the output of the IPC may be set to the value of a specified clamp voltage. If the input signal voltage does not exceed the reference voltage, the output of the IPC may track (or follow) the input signal voltage. For certain integrated circuits, the IPC may be configured to provide circuit protection for an input signal voltage ranging between 0V to 5V, and a power supply voltage ranging between 3.0V and 3.6V.

Abstract: A voltage reference is dynamically and digitally controlled by a digital function. The digital function may be implemented as a digital calculation or look up table. Inputs to the function include a modifiable trim value stored in a trim register, and a substrate temperature value. The preset value of the trim register is a trim preset value generated by cutting fuses and/or leaving fuses uncut. The cutting may be performed using laser trimming-devices. The output of the digital function is a corrected reference trim value that controls the gain of a voltage reference amplifier whose input is a band gap based voltage reference, and whose output is a derived voltage reference. The substrate temperature value is provided by a monolithic temperature monitor whose sensor may be on the same die as the derived voltage reference. The derived voltage reference provides a stable reference voltage that is dynamically and digitally controllable, to a host system that requires a voltage reference.

Abstract: A voltage reference is dynamically and digitally controlled by a digital function. The digital function may be implemented as a digital calculation or look up table. Inputs to the function include a modifiable trim value stored in a trim register, and a substrate temperature value. The preset value of the trim register is a trim preset value generated by cutting fuses and/or leaving fuses uncut. The cutting may be performed using laser trimming-devices. The output of the digital function is a corrected reference trim value that controls the gain of a voltage reference amplifier whose input is a band gap based voltage reference, and whose output is a derived voltage reference. The substrate temperature value is provided by a monolithic temperature monitor whose sensor may be on the same die as the derived voltage reference. The derived voltage reference provides a stable reference voltage that is dynamically and digitally controllable, to a host system that requires a voltage reference.

Abstract: A circuit and method for detecting an edge of the carrier frequency of received data from a remote IR communications device by an Infrared Communications Controller is disclosed. During the receiving of IR signals from a remote IR communications device such as, for example, a TV, VCR or stereo, a frequency window of frequencies above and below a predetermined carrier frequency is opened. If the edge of the carrier frequency of the received data falls within the frequency window, communications are established between the IrCC and the remote IR communications device. If the negative edge of the carrier frequency of the received data does not fall in the frequency window of frequencies, then the system aborts communications. Provisions are made for a ten percent (10%), a twenty percent (20%) frequency window, and a forty percent (40%) frequency window. Other configurations combining various percentage frequency windows are also disclosed as well as methods for generating the frequency windows.

Abstract: A method and apparatus for providing power management functions in a computer or other electronic system which includes a primary power supply, a trickle power supply and a battery back-up power supply. A power management circuit includes a storage element which stores an indication of the current turn-on or turn-off condition of the primary power supply. The power management circuit also includes a group of logic gates which process signals which are supplied to the storage element under normal operating conditions to control the turn-on or turn-off condition of the primary power supply. The power management circuit senses when the trickle supply is deactivated due to a line power failure or the like, and subsequently switches the power supply inputs of the storage element and certain of the logic gates from the trickle supply to the battery back-up supply.

Abstract: A clock generator circuit that produces clock signals at the logic signal transitions at an output in response to a sinewave input control signal derived from an oscillator includes a delay means connected in one of the inverter-amplifier stages to prevent unwanted noise-induced logic transitions at the output, thereby to reduce significantly the adverse effects of oscillator and power supply noise on the clock output signal.