Microchip Technology Inc.

Supertex, Inc.

Supentex, Inc.

Power Architects Corporation

Alexander Mednik

Rohit Tirumala

Marc Tan

Simon Krugly

David Schie

Wei Gu

James Nguyen

Ioan Stoichita

Wilson Wai-Sum Chan

Surya Talari

Sang Ton Ngo

Khai Minh Le

Zhibo Tao

Larry Kerenyi

A flyback converter to receive an input voltage and provide an output voltage is provided, and may include a transformer having a primary winding and secondary winding, a primary switch coupled to the primary winding, a synchronous rectifier device coupled to the secondary winding, and a secondary side control circuit to turn on the synchronous rectifier device by outputting a control signal at a first amplitude, subsequently modify the control signal to maintain a voltage across the synchronous rectifier device substantially constant until a predicted time that precedes a current in the synchronous rectifier device reaching substantially zero, subsequently turn off the synchronous rectifier device based on the voltage across the synchronous rectifier device reaching substantially zero, and subsequently turn on the synchronous rectifier device by outputting the control signal at a second amplitude, before the primary switch is turned on. The second amplitude is less than the first amplitude.

Secondary-side flyback converter controller

An emulated peak current mode control (EPCMC) synchronous buck converter device is provided, and may include a converter having an inductor, a high-side switch, and a low-side switch, and an EPCM controller. The controller may include a PWM latch to alternately turn on and off the high-side and low-side switches, a current sense element to output a current sense voltage based on the inductor current, and a feedforward circuit to generate a feedforward voltage. The current sense element outputs a first current sense voltage while the low-side switch is turned on, and outputs a second current sense voltage while the low-side switch is turned off. The feedforward voltage is generated based on a voltage differential that represents a difference between the first current sense voltage and the second current sense voltage, and the PWM latch alternately turns on and off the high-side and low-side switches based on the feedforward voltage.

DC-DC converter with improved line transient rejection

A self-biased non-isolated buck regulator is provided. The regulator may include a first input terminal and a second input terminal, a high-voltage switch coupled to the first input terminal, a low-voltage switch coupled to the high-voltage switch, an inductor having a first terminal coupled to the high-voltage switch and the first low-voltage switch, a high-voltage rectifier diode coupled between the first low-voltage switch and the second input terminal, a second low-voltage switch coupled to the first low-voltage switch and the high-voltage rectifier diode, and a capacitor having a first terminal coupled to the first terminal of the inductor, and a second terminal coupled to the second low-voltage switch.

Self-biased non-isolated low-power switching regulator

A multiple-phase parallelable constant on time (COT) buck controller, a first phase containing a first memory bit and a second phase containing a second memory bit. The COT buck controller includes a first converter comprising a first constant Tgenerator configured to sense and deliver a first Trequest when the first memory bit is in a logic one state, and a second converter connected in parallel with the first converter, the second converter comprising a second constant Tgenerator configured to sense and deliver a second Trequest when the second memory bit is in the logic one state, only one of the first memory bit and the second memory bit being in the logic one state thus generating activity in a daisy chain ring where each of the first converter and the second converter senses and delivers a corresponding Trequest in a sequential manner.

Multi-phase parallelable constant on time buck controller with phase interleaving ensured by ripple injection

A cascaded buck converter for receiving input voltage from an input voltage source and for delivering output voltage to a load. The converter includes a first inductor, a second inductor, a coupled inductor having a first winding connected in series with the first inductor and a second winding connected in series with the second inductor, an intermediate decoupling capacitor for receiving energy from the first inductor and the first winding and for supplying energy to the second inductor and the second winding, and an output decoupling capacitor for smoothening the output voltage at the load.

Coupled-inductor cascaded buck converter with fast transient response

A multi-phase DC-to-DC buck converter for receiving an input voltage and delivering an output voltage to a load by splitting the load current between a plurality of DC-to-DC buck converter cells. The converter includes a plurality of current sense circuits for sensing current in a respective converter cell, each of the current sense circuits configured to generate a respective current sense signal, an averaging circuit for receiving each of the respective current sense signals and generating an average signal, a plurality of imbalance detector circuits for comparing a respective current sense signal with the average signal and generating a respective current imbalance signal, and a plurality of ON time generators for activating a converter cell for a predetermined time interval and altering the predetermined time interval in accordance with a time integral of a respective current imbalance signal.

Method and apparatus for phase current balancing in multi-phase constant on-time buck converter

A high power-factor buck-boost converter having a rectified low-frequency AC line voltage input and a DC output is provided. The converter may include a magnetic element, a controlled switch having a gate terminal and a drain terminal that is coupled to the magnetic element, a rectifier diode coupled to the magnetic element, an output smoothing capacitor coupled to the rectifier diode, and a control circuit having an output coupled to the gate terminal of the controlled switch for repeatedly turning the controlled switch off for a first time duration and on for a second time duration. The second time duration may be determined as a function of the first time duration immediately preceding the second time duration.

Buck-boost controller achieving high power factor and valley switching

The invention relates to methods for supplying current to an auxiliary power supply for the control circuit of a switching regulator. The auxiliary power supply is connected in parallel to a first switch of the switching regulator. The auxiliary power supply comprises a second switch. During the nonswitching stage of the switching regulator, the second switch has significant impedance so as to power up the auxiliary power supply gradually and to suppress the flow of large or oscillatory currents which may cause damage or create interference. During the switching stage of the switching regulator, the second switch has negligible impedance so as to avoid undue dissipation within the path for the supply of current.

Auxiliary power supply for a control circuit of a switching regulator

A zero-voltage switching buck converter circuit and control circuit are provided. The buck converter circuit may include a first inductor, a smoothing capacitor coupled to the first inductor, a rectifier diode coupled in parallel with the first inductor and the smoothing capacitor, a control switch coupled to the first inductor, a control circuit configured to turn the control switch off and on repeatedly at a high frequency rate; and a snubber network coupled to the first inductor and the control circuit. The snubber network may include second and third inductors connected in series, wherein one terminal of the first inductor is connected to a node connecting the second and third inductors, and an auxiliary switch connected to the control circuit. A first terminal of the second inductor that is not connected to the node may be coupled to the control switch, and a first terminal of the third inductor that is not connected to the node may be coupled to the auxiliary switch.

Zero-voltage switching buck converter and control circuit therefor

A circuit and method are provided detecting a persistent short circuit in a power MOSFET for the purpose of protecting a load from over-current.

Circuit and method for detecting short circuit failure of a switching transistor

A constant-current controller with square wave input current shaping for driving a series of light emitting diodes (LEDs) is provided. The controller may include a sample and hold circuit that samples a current sense voltage, a first multiplier circuit that multiplies an output of the sample and hold circuit, an error detector circuit that compares an output of the multiplier circuit with a reference voltage, an error amplifier that amplifies an output of the error detector circuit, a second multiplier circuit that multiplies an output of the error amplifier by a coefficient, and an output circuit that outputs a pulse-width modulated control signal based on an output of the second multiplier circuit. The coefficient may vary depending on whether the constant-current LED driver controller is used with a boost converter or a buck-boost converter.

Constant-current controller with square-wave input current shaping

The invention relates to the control of auxiliary power supply connected in parallel with a switch of a switching regulator. A switch and a diode are included within the connection to the auxiliary supply. The auxiliary supply switch enables a flow of current to the auxiliary supply when the auxiliary supply switch is on and the switch in parallel is off. The auxiliary diode prevents a reverse flow of current when the switch in parallel is on. The auxiliary power supply is suitable to supply of current in both stages of switching regulator operation, to configurations with a common node carrying either type of potential, steady or switching, provides supply of current at high efficiency in the switching stage of switching regulator operation, and provides high efficiency over a wide range of operating conditions of the switching regulator.

Auxiliary power supplies in parallel with a switch of a switching regulator

A communication method and apparatus that uses modulation of post-conduction oscillation frequency in switching converters is provided. The apparatus may include a converter having a magnetic element having a primary winding and a secondary winding, a first switch, a control circuit configured to repeatedly activate the first switch to couple an input voltage source to the primary winding to store electrical energy in the magnetic element, and a diode coupled to the secondary winding, said diode configured to couple the secondary winding to a load to deliver the electrical energy stored in the magnetic element, and a communication apparatus having a second switch, a first modulator capacitor coupled to the secondary winding, a first transmitter configured to activate the second switch in accordance with a first input signal, and a first receiver configured to detect a post-conduction oscillation frequency of a voltage signal at the primary or secondary windings.

Communication method and apparatus using modulation of post-conduction oscillation frequency in switching converters

A comparator sense input is disconnected from a current sense resistor for the duration of a switching transition in an adjacent channel(s). Instead, the sense input receives a signal of the magnitude and the slew rate sampled prior to the transition.

Circuit and method for active crosstalk reduction in multiple-channel power supply controllers

The invention comprises a dimming switch for use with a string of light emitting diodes (LEDs). The dimming switch comprises a bipolar junction transistor (BJT) driven in a cascode scheme. The dimming switch also comprises circuitry to offset the current that drives the base of the BJT to provide a controlled amount of current to the LEDs when the dimming input signal is high.

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Campbell, CA, United States of America

Alexander Mednik