Semiconductor Components Industries, LLC

Fairchild Korea Semiconductor Ltd.

Inki Park

Taesung Kim

Seunguk Yang

Jintae Kim

Sangcheol Moon

Hyunchul Eum

JooHoon Kim

Eungwoo Lee

A power converter includes a transformer, a first primary side transistor coupled to the primary winding, a primary side controller that provides a gate signal to a gate of the first primary side transistor, a first synchronous rectifier (SR) transistor, and an SR controller. The first SR transistor has a drain coupled to a secondary winding of the transformer, a gate for receiving a first SR gate signal, and a source coupled to a first output terminal of the power converter. The SR controller is coupled to the gate and drain of the first SR transistor, for activating the first SR gate signal when a voltage on the drain falls below a turn-on threshold, and deactivating the first SR gate signal when a voltage on the drain rises above a variable turn-off threshold, wherein the variable turn-off threshold increases over an expected on-time of the first SR gate signal.

Synchronous rectifier control for switched mode power supplies and method therefor

A power supply device includes a power switch that is switched according to a gate voltage. A sense resistor receives a switch current that flows through the power switch to develop a sense voltage. A peak of a primary-side current is detected from the sense voltage. The gate driver has a pair of switches for generating the gate voltage in accordance with a control signal. When a low-side switch of the gate driver is turned on according to the control signal, the gate voltage of the power switch decreases as a sink current flows from the gate of the power switch via the transistor.

Coupling structure of gate driver in power supply device

An LED control circuit controls a switching operation of a switch by hysteretic control. The LED control circuit includes a controller integrated circuit (IC) that senses a current sense voltage from a current sense resistor that is on a low-side of the switch. The LED control circuit senses the current sense voltage during on-time of the switch to determine when to turn off the switch. During off-time of the switch, the controller IC determines when to turn on the switch by comparing a sawtooth voltage to a turn-on threshold that is generated from the on-time of the switch.

Light emitting diode control circuit with hysteretic control and low-side output current sensing

A light emitting diode (LED) lighting circuit includes a ripple reducer. The ripple reducer includes a ripple detector, an adaptive offset generator, and a linear regulator. The ripple detector generates a ripple voltage that is indicative of a ripple current. The adaptive offset generator generates an adaptive offset voltage from the ripple voltage and from a voltage of a transistor. The linear regulator drives the transistor to regulate an LED current in accordance with a reference control voltage that is generated from the ripple voltage and the adaptive offset voltage.

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Seoul, South Korea

Inki Park