National Semiconductor Corporation

Richard Frank

Tamas S Szepesi

Bruce Lee Inn

Michael Eugene Broach

Michael John Collins

Siew Siong Teo

Denis Michel Darmon

A charge pump is provided. The charge pump may include an oscillator, a first switch, a second switch, a capacitor/switch network, an error amplifier, an adjustable resistance circuit, a first switch driver, and a second switch driver. In one embodiment, the first and second drivers each receive the oscillator voltage, and drive the first and second switches, respectively. Further, the adjustable resistance circuit is connected in series with the first and second switch circuits. The charge pump is arranged in a closed loop with the error amplifier driving the adjustable resistance circuit. The resistance of the adjustable resistance circuit is modulated to regulate the output voltage.

Apparatus and method for charge pump control with adjustable series resistance

A circuit is arranged to provide a thermal shutdown signal in response to an overtemperature condition. The thermal shutdown circuit is typically implemented in the same die as the circuitry that is to be protected. The thermal shutdown circuit provides a first current in response to a change in temperature when a VBE associated with a transistor decreases below a predetermined level. The first current is mirrored to provide a scaled current. A thermal shutdown signal is activated when the scaled current becomes greater than a reference current. The first current is increased in response to the activated thermal shutdown signal such that the thermal shutdown circuit is deactivated at a temperature that is lower than the temperature at which the circuit is activated. The thermal shutdown circuit is deactivated when the temperature of the die decreases.

Thermal shutdown circuit

An integrated circuit system and method provides a reliable low voltage reference including undervoltage lockout capabilities that prevent a premature or false response. A physical constant trigger circuit initiates a response based upon a physical constant (e.g. a stable point associated with a voltage summation in a transistor circuit with components configured to produce equal and opposite temperature coefficients). A response includes changing polarities of the transistor circuit at a predetermined inflection point. A comparator compares signals from the physical constant trigger circuit and determines when a change occurs in the response. A voltage divider provides a varying voltage to the physical constant trigger and when the voltage level corresponds to the physical constant it is utilized as the reference voltage. An input signal port conveys an input signal to the voltage divider and output port conveys an indication of the response (e.g., a desired reference voltage is available).

Precision low voltage supply system and method with undervoltage lockout capabilities

An apparatus for sensing current in a switching device having resistive voltage-current characteristics includes a first and second power terminal (typically common or ground) for the application therebetween of an operating potential (or alternatively, power), an impedance connected between the first power terminal and a node, a switching device having its main conduction path connected between the node and the second power terminal for controlling the flow of current through the impedance, at least one sense device coupled to the node, operative to sense or divide the potential at the node to thereby provide a sensing potential, where at least one of the sense devices is switched only during at least a portion of the period when the switching device is turned on, and a voltage reference generating circuit operative to generate a reference voltage for comparison with the sensed potential. A method for sensing current in a switching device having resistive voltage-current characteristics, samples the potential at a node connecting the switching device to the impedance only during at least a portion of the period when the switching device is tuned on, to generate a sensed potential, generates a reference potential for comparison with the sensed potential.

Methods and apparatus for sensing currents

An apparatus for sensing current in a switching device having resistive voltage-current characteristics includes a first and second power terminal (typically common or ground) for the application therebetween of an operating potential (or alternatively, power), an impedance connected between the first power terminal and a node, a switching device having its main conduction path connected between the node and the second power terminal for controlling the flow of current through the impedance, at least one sense device coupled to the node, operative to sense or divide the potential at the node to thereby provide a sensing potential, where at least one of the sense devices is switched only during at least a portion of the period when the switching device is turned on, and a voltage reference generating circuit operative to generate a reference voltage for comparison with the sensed potential. A method for sensing current in a switching device having resistive voltage-current characteristics, samples the potential at a node connecting the switching device to the impedance only during at least a portion of the period when the switching device is turned on, to generate a sensed potential, generates a reference potential for comparison with the sensed potential.

Growing community of inventors

Longmont, CO, United States of America

Richard Frank