Patent application number | Description | Published |
20080224625 | Constant current light emitting diode (LED) driver circuit and method - A drive circuit supplies a drive current to a plurality of light emitting diodes. The drive circuit includes a voltage converter circuit having a particular topology and including at least one inductive element and at least one switching element. The drive circuit senses a current through one of the inductive and switching elements and generates a feedback signal from the sensed current. The feedback signal has a value indicating the drive current being supplied to the light emitting diodes and the drive circuit controls the operation of the voltage converter responsive to the feedback signal. | 09-18-2008 |
20090195168 | METHOD AND SYSTEM FOR DIMMING AC-POWERED LIGHT EMITTING DIODE (LED) LIGHTING SYSTEMS USING CONVENTIONAL INCANDESCENT DIMMERS - A dimming control circuit for dimming light emitting diodes receives an AC input voltage signal from a dimming circuit. The control circuit includes a power stage and a current control loop coupled to the power stage. An AC detector is operable to detect an instantaneous value of the AC input voltage signal and to generate a signal indicating whether the AC input voltage signal is present or absent. A current control circuit is operable responsive to the signal to adjust the operation of the current control loop and to control current through the light emitting diodes to achieve the desired dimming, and to prevent inrush current on the AC input voltage signal. | 08-06-2009 |
20110286245 | DC/DC POWER CONVERTER HAVING ACTIVE SELF DRIVING SYNCHRONOUS RECTIFICATION - A DC/DC voltage converter includes a transformer having a primary side and a secondary side. Primary side circuitry is connected to the primary side and includes a first pair of switching transistors controlled responsive to first control signals from the primary side of the transformer and receiving an input voltage. Secondary side circuitry is connected to the secondary side and includes a second pair of switching transistors controlled responsive to second control signals from the secondary side of the transformer and providing an output voltage. Driver circuitry generates the second control signals responsive to drain and source voltages at each of the second pair of switching transistors and a first and second PWM control signals. Signal shaping circuitry provides the first and second PWM control signals responsive to a drain voltage of each of the second pair of switching transistors. | 11-24-2011 |
20120008359 | ASYMMETRIC ZERO-VOLTAGE SWITCHING FULL-BRIDGE POWER CONVERTERS - Disclosed are full-bridge power converters providing DC output power at increased conversion efficiencies, and methods of operating full-bridge power converters providing DC output power at increased conversion efficiencies. In disclosed embodiments, the switches of the full-bridge are operated to reduce conduction losses and to provide for zero-voltage switching. | 01-12-2012 |
20140003104 | ACTIVE RECTIFICATION WITH CURRENT-SENSE CONTROL | 01-02-2014 |
Patent application number | Description | Published |
20110025217 | INRUSH CURRENT LIMITER FOR AN LED DRIVER - An inrush current limiter for use with an LED driver including a current limiting device, a bypass switch device, and a switch drive. The current limiting device is placed in the input current path of the LED driver to limit input current to a predetermined maximum level in response to an AC conductive angle modulated voltage. The bypass switch device is coupled in parallel with the current limit device. The switch drive turns on the bypass switch device to at least partially bypass the current limiting device as a voltage level of an input of a switching converter rises. The input current remains sufficiently high without exceeding the maximum level. The switch drive is implemented with a delay network driven either by a separate transformer winding or by a snubber network. The delay network may have a delay based on the delay caused by the current limiting device. | 02-03-2011 |
20110101877 | LED DRIVER WITH OPEN LOOP DIMMING CONTROL - An LED driver with open loop dimming including a full wave rectifier circuit, a DC/DC converter, and an oscillator circuit. The rectifier is configured to receive an input voltage in the form of an AC conductive angle modulated voltage and to provide a rectified voltage. The DC/DC converter converts the rectified voltage to an output voltage and an output current, where the output current has a magnitude which varies proportionately with a square of a quadratic mean of the input voltage. The oscillator circuit controls switching of the DC/DC converter with constant frequency and constant duty cycle. The DC/DC converter may be a flyback converter and may include a transformer operated in DCM. The driver may include output voltage and/or output current limit. The output current may be limited when the input voltage is within normal operating range of an AC line voltage from which the input voltage is derived. | 05-05-2011 |
20130207555 | LED DRIVER SYSTEM WITH DIMMER DETECTION - An LED driver system including an input receiving a rectified AC conductive angle modulated voltage on a rectified node, a converter, a low-pass filter, and AC detector, and a driver network. The converter is to the rectified node and includes a power switching device coupled to a switching node, in which the power switching device is controlled to convert the rectified AC conductive angle modulated voltage to an output voltage and output current. The low-pass filter is configured to filter voltage of the switching node to provide a filtered voltage. The AC detector receives the filtered voltage and provides a current sense signal indicative thereof. The driver network controls duty cycle of the power switching device based on the current sense signal. | 08-15-2013 |