Microsemi Corporation

Linfinity Microelectronics

Hwangsoo Choi

Shiju Wang

Chien Nguyen

Mike Lewis

Dror Korcharz

Alon Zeev Ferentz

Arkadiy Peker

Chii-Fa Chiou

Migel Jacubovski

A power supply arrangement constituted of: an isolated power supply having a primary side and a secondary side, the secondary side electrically isolated from the primary side; a common mode choke having a first winding and a second winding wound on a common core, the common mode choke coupled between the primary side of the isolated power supply and an AC mains; and a shielding surrounding the common mode choke, the shielding coupled to a common potential of the secondary side of the isolated power supply.

EMI suppression with shielded common mode choke

A power source constituted of: a power factor corrector controller; an electronically controlled switch responsive to the power factor corrector controller; a first inductor serially connected with the electronically controlled switch and arranged to pass a direct current there through when the electronically controlled switch is closed; a second inductor magnetically coupled to the first inductor and coupled to provide power to a load in a flyback arrangement; a third inductor magnetically coupled to the first inductor, a first end of the third inductor arranged to provide a representation of the voltage level of the direct current when the electronically controlled switch is closed, and to provide a representation of the voltage level of the power provided to the load when the electronically controlled switch is open; and an off time control circuit in communication with the power factor corrector controller and responsive to the third inductor representations.

Flyback with switching frequency responsive to load and input voltage

A lighting circuit constituted of: a single dimming input; a pulse width modulation acceptance circuit arranged to convert a pulse width modulated dimming signal received at the single dimming input into a local dimming signal, the local dimming signal exhibiting a predetermined format; an analog voltage level acceptance circuit arranged to convert an analog voltage dimming signal received at the single dimming input into the local dimming signal exhibiting the predetermined format; and a luminaire driving circuit responsive to the local dimming signal.

Dimming input suitable for multiple dimming signal types

A start up circuit constituted of: a first alternating current lead; a second alternating current lead, said second alternating current lead exhibiting an opposing phase of said first alternating current lead; a first capacitor, a first end of said first capacitor coupled to said first alternating current lead; a second capacitor, a first end of said second capacitor coupled to said second alternating current lead; a breakdown diode coupled between a second end of said first capacitor and a second end of said second capacitor; and a third capacitor coupled in parallel with said breakdown diode. A direct current power is developed across the breakdown diode without requiring dissipative elements.

Non-dissipative start up circuit

A controller for an inverter provides variable gain control in a voltage regulation loop to prevent overshoot in an output voltage of the inverter. A feedback circuit senses the output voltage and provides a voltage feedback signal to the controller. The controller includes a voltage conversion circuit and an error amplifier as part of the voltage regulation loop. A gain control block varies a circuit parameter in the voltage conversion circuit or the error amplifier such that regulation of the output voltage starts at a relatively lower voltage level and increases smoothly to a desired level.

Voltage regulation loop with variable gain control for inverter circuit

A shoot-through prevention circuit is used in a power conversion circuit that uses a passive level-shifter to drive a P-type transistor in a switching network. The shoot-through prevention circuit is coupled between a controller output that provides a driving signal to control the P-type transistor and the passive level-shifter coupled to a control terminal of the P-type transistor. The shoot-through prevention circuit couples the controller output to the passive level-shifter when the driving signal has a first logic level associated with turning on the P-type transistor and isolates the controller output from the passive level-shifter when the driving signal has a second logic level associated with turning off the P-type transistor.

Shoot-through prevention circuit for passive level-shifter

An efficient power conversion circuit for driving a fluorescent lamp uses a minimum pulse generator circuit to control the minimum on-time of a time modulated signal to increase the dimming range of the fluorescent lamp operating over a wide range of temperature and supply voltage. A minimum number of lamp current cycles with respective amplitudes above a preset threshold is typically required to avoid flickering or shimmering during minimum brightness. The minimum pulse generator circuit counts the lamp current cycles and adjusts the on-time accordingly to guarantee the minimum number of cycles with respective amplitudes above a preset threshold under all operating conditions.

Method and apparatus for controlling minimum brightness of a fluorescent lamp

A power conversion circuit senses an output voltage to detect shorted lamp conditions in a backlight system. The power conversion circuit can drive at least one fluorescent lamp. A voltage sensing feedback circuit, such as a capacitive voltage divider or a resistive voltage divider, senses the output voltage at an output of the power conversion circuit and generates a voltage feedback signal for a shorted lamp detector. The shorted lamp detector reliably detects a shorted lamp condition of one fluorescent lamp in a multi-lamp configuration or detects a short circuit condition of the output voltage line coupling the output voltage of the power conversion circuit to the fluorescent lamps.

Shorted lamp detection in backlight system

Method and apparatus for controlling minimum brightness of a flourescent lamp

All efficient power conversion circuit for driving a fluorescent lamp uses a minimum pulse generator circuit to control the minimum on-time of a time modulated signal to increase the dimming range of the fluorescent lamp operating over a wide range of temperature and supply voltage. A minimum number of lamp current cycles with respective amplitudes above a preset threshold is typically required to avoid flickering or shimmering during minimum brightness. The minimum pulse generator circuit counts the lamp current cycles and adjusts the on-time accordingly to guarantee the minimum number of cycles with respective amplitudes above a preset threshold under all operating conditions.

Growing community of inventors

Fullerton, CA, United States of America

Hwangsoo Choi