Linear Technology Corporation

Steven Leo Martin

Trevor Wayne Barcelo

Samuel Hodson Nork

David Justin Simmons

William Louis Walter

Mark Robert Vitunic

Roger A Zemke

High efficiency drive circuitry for a group of parallel-connected light emitting devices, in which each device is driven in series by a respective source of bias current. The maximum voltage drop among the group of biased light emitting devices is determined and in response, a control voltage to drive all the light emitting device at the lowest effective voltage for the LED group is produced.

Circuitry and methodology for driving multiple light emitting devices

An apparatus and method for a portable device incorporating a battery and a battery charger. In the portable device, there are a plurality of system components configured to facilitate a plurality of functions that the portable device is designed to perform. The battery in the portable device is configured for providing an internal power supply to the plurality of system components in the absence of an external input power supply. The battery charger is configured for charging the battery when the external input power supply is available. The battery charger disclosed herein is capable of supplying system power to the system components when voltage of the battery that is being charged is below a limit, thereby allowing the portable device to operate when voltage of the battery drops below the limit.

Method and system for minimum output-voltage battery charger

An over-voltage protection circuit for use in low power integrated circuits is provided. The over-voltage protection circuit distributes certain connection and conditioning circuitry to a component network external to the integrated circuit. As a result, the integrated circuit need not be created with specialized high voltage components, significantly reducing its cost and complexity, and allowing it to be used in a wider range of end-user applications.

Over-voltage protection circuit

A switching circuit for converting an input voltage into an output voltage has an input terminal for receiving the input voltage. A power switching element is coupled to the input terminal and has duty cycle d controllable to adjust the output voltage with respect to a desired level using inductor current representing current in an inductor element connectable to the power switching element. An average and hold circuit is responsive to a voltage at an output of the power switching element to produce an average switch voltage over an ON phase of a switching cycle of the power switching element. A voltage-to-current converter is responsive to the average switch voltage for producing representation of an average inductor current over one or more switching cycles. A current modulator having a duty cycle equal to 1-d modulates the representation of the average inductor current to produce a signal proportional to an average output current of the switching circuit over one or more switching cycles.

Determining average output current in DC-DC converter

A switching circuit coupled to one or more input sources and having one or more switching elements controlled to produce an output for charging a battery. A first control circuit is responsive to current of the switching circuit for producing a first control signal to drive the switching element so as to control the current. A second control circuit is responsive to voltage at the battery for producing a second control signal to drive the switching element so as to control voltage developed across the battery. A selector circuit is responsive to the first and second control signals for selectively controlling the switching element.

Switching battery charger with programmable current control and power control

A power manager is configured to manage power for a battery-powered application. A power source, a load and a battery are interconnected through a circuit path. Power from the power source is provided to the load and battery by a switching regulator. Various implementations are presented.

Power manager and power managing method for battery-powered application

A charge pump DC/DC converter with reduced noise at the input voltage source is provided. The present invention includes buck and boost DC/DC converters with added circuitry coupled between the input voltage and the switches which maintains a substantially constant input current on both phases of the charge pump clock. The added circuitry reduces input current variations to provide reduced noise at the input voltage source. Feedback loop circuitry coupled between the output node and the added circuitry varies the current through the switches to control the output current of the DC/DC converter in order to maintain the output voltage at the regulated value. The added circuitry may comprise a variable resistor, current mirror, or current mirrors.

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Chelmsford, MA, United States of America

Steven Leo Martin