Microsemi Corporation

Bruce Ferguson

George C Henry

Roger Holliday

Shawn Anthony Fahrenbruch

Ekrem Cengelci

Paul Okada

A dual level current limit apparatus constituted of: an electronically controlled switch coupled between a load and a line voltage; and a control circuitry arranged to alternately: control said electronically controlled switch to limit the magnitude of current flowing therethrough responsive to the difference between a predetermined first function of the current magnitude and a predetermined reference voltage, and control said electronically controlled switch to limit the magnitude of current flowing therethrough responsive to the difference between said first function of the current magnitude and a predetermined second function of the load voltage.

Dual level current limit apparatus and method

A current sensing system constituted of: an impedance element; a switching network arranged to alternately couple a first end of the impedance element between a supply voltage and return, the impedance element arranged to develop a voltage there across reflecting a current flow to a load coupled to the second end of the impedance element; a first stage amplifier, a first and second input thereof respectively coupled to the first and second end of the impedance element, a power supply input thereof coupled to a voltage greater than the supply voltage and a return thereof coupled to the first end of the impedance element, the amplifier having a first and second output, the potential difference reflecting the impedance element voltage times a first stage gain; and a second stage amplifier, a first and second input thereof respectively coupled to a first and second output of the first stage amplifier.

Current sensing system and method

A safety mechanism for a solar cell group, the safety mechanism constituted of: a signal receiver arranged to assert a permissive signal indicative of reception by the signal receiver of a predetermined signal; an electronically controlled switch arranged to provide in a closed state an effective short circuit across the output of the solar cell group responsive to the absence of the asserted permissive signal of the signal receiver; and a power harvester in communication with the solar cell group and arranged to provide electric power to the signal receiver when the electronically controlled switch is the closed state.

Photo-voltaic safety de-energizing device

A hysteretic power converter wherein an additional adjustment circuit, implemented as an offset correction loop, adds an offset to the comparator detection function to reduce the difference between the average output voltage and the regulation set point voltage. The adjustment circuit lies outside the main hysteretic regulation loop and therefore does not substantially impact the response time of the hysteretic loop, and is slow acting responsive to a low pass filter.

Hysteretic voltage converter with offset voltage correction

An ambient light sensor produces a current signal that varies linearly with the level of ambient light. The current signal is multiplied by a user dimming preference to generate a brightness control signal that automatically compensates for ambient light variations in visual information display systems. The multiplying function provides noticeable user dimming control at relatively high ambient light levels.

Method and apparatus to control display brightness with ambient light correction

A battery charger for an electronic device receives current limited power from an external power source, such as a Universal Serial Bus power interface. The battery charger can linearly regulate a charging current to an internal battery and limit the charging current so as not to demand current in excess of what the external power source can provide. A bi-directional pass element coupled between a system power terminal and the internal battery controls the charging current and effectively isolates the internal battery from a system load during charging of the battery while providing a low impedance path from the internal battery to the system load during discharging of the battery.

Battery charging and discharging by using a bi-directional transistor

An electronically controlled four quadrant MOSFET based switch in which a pair of drivers are provided in cooperation with a MOSFET. A first one of the drivers is arranged such that when current flow through the MOSFET is to be enabled responsive to a first condition of the control signal, the gate of the MOSFET is driven with an appropriate voltage, and when current flow through the MOSFET is to be disabled responsive to a second condition of the control signal, the gate is driven towards a limit voltage. A second one of the drivers is arranged such that when current flow through the MOSFET is to be enabled the body diode connection of the MOSFET is driven towards the potential of the MOSFET source, and when current flow through the MOSFET is to be disabled the body diode connection is driven towards the limit voltage.

Four quadrant MOSFET based switch

A secondary side voltage regulation scheme applied to a multiple output flyback converter. The output with the highest error voltage is selected to control the primary switch. The remaining outputs are regulated by varying the length of time that current is allowed to flow into each output by controlling the on time of a switch connected in series with each of the outputs. The switching of the windings is achieved using a single N channel MOSFET for each output. Regulation of the outputs is performed using leading edge modulation. The body diode of the output MOSFET switches are held off during the start of the commutation period by the use of an active clamp on the primary side.

Fine tuned multiple output converter

Linearly regulated battery charger

A backlight intensity for a transflective display increases proportionately with increasing ambient light levels for a first range of ambient light levels and decreases proportionately with increasing ambient levels for a second range of ambient light levels to improve power efficiency. The second range of ambient light levels is higher than the first range of ambient light levels.

Dual-slope brightness control for transflective displays

An illumination control circuit allows a user to set a desired brightness level and maintains the desired brightness level over temperature and life of a light source. The illumination control circuit uses a dual feedback loop with both optical and thermal feedbacks. The optical feedback loop controls power to the light source during normal operations. The thermal feedback loop overrides the optical feedback loop when the temperature of the light source becomes excessive.

Growing community of inventors

Anaheim, CA, United States of America

Bruce Ferguson