Intersil Americas Inc.

Xiaodong Zhan

Xiangxu Yu

Fred F Greenfeld

Zhixiang Liang

David B Bell

A power supply including an AC input, a filter, a full wave rectifier, a converter, a second rectifier, and a bias system. The filter includes at least one differential capacitor coupled to the AC input. The full wave rectifier develops a DC bus voltage on a DC bus node. The converter includes a controller and operates to convert the DC bus voltage to a regulated output voltage. The second rectifier is coupled to the AC input for developing a DC bias voltage on a DC bias node. The bias system is coupled between the DC bias node and a reference node and provides at least one start-up voltage to the controller, such as a supply voltage or a sense voltage or the like. The bias circuit includes at least one current discharge path for discharging each differential capacitor within a predetermined time period when AC line voltage is removed.

Bias and discharge system for low power loss start up and input capacitance discharge

A power supply including a converter, a capacitance, and a hiccup control module. The converter converts an input voltage to both an output voltage and a preliminary standby voltage when in its active state. The capacitance stores the preliminary standby voltage which is charged to an upper voltage level when the converter is in its active state and which is discharged to a lower voltage level when the converter is in its inactive state. During the standby mode, the hiccup control module operates the converter in hiccup mode by toggling between placing the converter into its inactive state when the preliminary standby voltage is charged to the upper voltage level and placing the converter into its active state when the preliminary standby voltage is discharged to the lower voltage level. The hiccup mode of the power supply eliminates a need for a separate standby converter.

Power supply with low power consumption hiccup standby operation

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.

LED driver with open loop dimming control

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.

Inrush current limiter for an LED driver

An apparatus comprises a synchronous converter for providing a regulated output voltage responsive to an input voltage, a control PWM signal to a control switch of the synchronous converter and a synchronous PWM signal to a synchronous switch of the synchronous converter. A first circuit generates the control PWM signal and the synchronous PWM signal responsive to a PWM control signal. The first circuit limits a maximum duty cycle of the synchronous PWM signal to a predetermined level.

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Plano, TX, United States of America

Xiaodong Zhan