Abstract: A method and apparatus for limiting current through a switching device supplying current to a load. A control evaluates a model representing the switching device temperature as a nonlinear function of current and time. The model compares the temperature of the switching device to a maximum allowable temperature. The current limit is defaulted to peak current; and in response to the model detecting a temperature in excess of the maximum allowable temperature, a nominal current limit is set. The current limit reset to peak current after the model detects a switching device temperature a predetermined magnitude below the maximum allowable temperature.

Abstract: A control circuit system for controlling one or more parameters in a circuit with at least one operational stage is disclosed, in the form of a delay stage or a logic stage, the operational stage comprising at least one operational circuit, at least one operational current source for supplying a drive current for the operational stage, and at least one operational load. The operational stage also comprises a number of controllable components of the operational current source and of the operational load, allowing control of the size of the drive current and of the load, respectively, in the operational stage. At least one reference stage includes essentially an image circuit of the operational stage with a reference current source for supplying a drive current for the reference stage and a reference load, comprising a number of controllable reference components, allowing control of the size of the drive current and the load, respectively, of the reference stage.

Abstract: This invention provides an automatic current interruption to protect the audio power amplifier circuitry when current conditions above the capacity of the power amplifier are encountered. The circuit monitors the current supplied to the power amplifier and utilizes a transistor to interrupt power amplifier output. Power output is latched in its interrupted state until reset and is capable of quickly and effectively shutting down power supply output.

Abstract: An improved power operational amplifier device is disclosed which provides a floating buffer having a first and second RC time constant for controlling a first bank of MOSFET transistors in an output portion of the device. In addition, the power operational amplifier includes a fixed buffer having a third RC time constant for controlling a second bank of MOSFET transistors located in an output portion of the device. A current limit section is coupled to both the floating buffer and the fixed buffer, and, in addition, the current limit section of the improved power operational amplifier has an oscillation stabilizer portion for limiting oscillations of output current during output stage current limit operation. The device also includes an output portion coupled to each of the floating buffer, the fixed buffer, and the current limit section.

Abstract: An active deassertion circuit is a device that prevents signal lines used with a communications protocol from drawing too much current. Thus, the device prevents the driver(s) of the signal lines from malfunctioning and/or being damaged. The active deassertion circuit is comprised of a voltage regulator, with peripheral connections, coupled to a transistor that is used to sink excess current. The function of these elements ensures that no asserted signal line draws too much current if another signal line is actively deasserted. A method of using the active deassertion circuit is also disclosed.

Abstract: A charge pump has a reference circuitry (18, 20, 22), a first parallel current path (16), at least one second parallel current path (16), a mirror circuit (46), a sourcing circuitry (60, 62) and a sinking circuitry (50, 54, 66, 68). The first and the at least one second parallel current path sink current from a first node responsive to a predetermined voltage generated by the reference circuitry. The at least one second current path also operates responsive to a control signal. The mirror circuit generates a second predetermined voltage responsive to the total current sunk from the first node. The sourcing circuitry and the sinking circuitry sourcing and sinking a current from the output node, respectively, responsive to the second predetermined voltage and to a control signal. The disclosed charge pump may be incorporated into a phase locked loop circuit where constant stability parameters are desired.