Abstract: A ripple reduction circuit is provided. The ripple reduction circuit may include a ripple capacitor configured to drive at least a first segment of a string of light emitting diodes (LEDs), a first diode having an anode coupled to the ripple capacitor, and a cathode configured to be coupled to an input end of the first LED segment, a second diode having a cathode coupled to the ripple capacitor and the anode of the first diode, and an anode configured to be coupled between the first LED segment and a second LED segment of the string of LEDs, a third diode having an anode coupled to the ripple capacitor, and a cathode configured to be coupled to a last LED segment of the string of LEDs, and a fourth diode having a cathode coupled to the ripple capacitor and the anode of the third diode.
Abstract: 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.
Abstract: 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.
Type:
Grant
Filed:
June 18, 2015
Date of Patent:
May 23, 2017
Assignee:
Microchip Technology Inc.
Inventors:
Alexander Mednik, Rohit Tirumala, Marc Tan, Simon Krugly
Abstract: 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.
Abstract: 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.
Type:
Grant
Filed:
June 21, 2013
Date of Patent:
April 11, 2017
Assignee:
Microchip Technology Inc.
Inventors:
Marc Tan, Alexander Mednik, Simon Krugly, Wilson Wai-Sum Chan
Abstract: Systems and methods are disclosed for operating a highly linearized resistance for a switch through use of a bootstrapped features. In one exemplary implementation, there is provided a method and system that implements a method for operating a circuit configured to provide a highly linearized resistance including receiving a signal via a bootstrapped switch, coupling the received signal to a gate if the received signal is high, receiving a signal via a switch control input coupled to a high impedance element. Moreover, the method includes coupling the high impedance element to the gate and turning off the switch via a gate turn off when the gate turn off pulls the gate low.
Type:
Grant
Filed:
August 3, 2015
Date of Patent:
April 11, 2017
Assignee:
Microchip Technology Inc.
Inventors:
Benedict C. K. Choy, James T. Walker, Ming-Yuan Yeh
Abstract: 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.
Abstract: 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.
Type:
Grant
Filed:
June 17, 2015
Date of Patent:
March 7, 2017
Assignee:
Microchip Technology Inc.
Inventors:
Alexander Mednik, Rohit Tirumala, Marc Tan, Simon Krugly
Abstract: The invention generally relates to the field of power factor correction and specifically to generation of a reference waveform which is proportional to line voltage and is controllable in amplitude.
Abstract: Employed within an LED driver operating from the AC power line, the invention controls both input current and output power. With this regulation circuit, input current appears purely resistive, precisely tracking the input voltage waveshape. At the same time, it provides good line regulation and inherent phase dimmer compatibility, requiring no special circuitry to detect and handle a dimmer.
Abstract: A capacitive parametric zero crossing detection circuit has a nonlinear voltage controlled capacitive device coupled to an input voltage to convert a zero crossing current pulse into zero crossing voltage signal.
Abstract: 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.
Abstract: An adjustable shunt regulator circuit has two current paths in parallel, with each current path having a bipolar transistor therein with the bases of the bipolar transistors of the two current paths connected in common. One of the current paths has a high impedance node. A MOS transistor has a gate connected to the high impedance node, and a source and a drain. A resistor divide circuit is connected in parallel to the source and drain of the MOS transistor and provides the output of the regulator circuit. The resistor divide circuit has a first resistor connected in series with a second resistor at a first node. A feedback connects the first node to the bases of the bipolar transistors connected in common of the two current paths.
Abstract: A switching power converter has an input voltage source. An output load is coupled to the input voltage source. An inductive element is coupled to the load. A switch is coupled to the inductive element. A control circuit is coupled to the switch and the inductive element for activating and deactivating the switch, the control circuit activating and deactivating the switch based on a negative voltage drop across a resistive element of the control circuit.
Type:
Grant
Filed:
July 22, 2013
Date of Patent:
May 10, 2016
Assignee:
Microchip Technology Inc.
Inventors:
Alexander Mednik, Simon Krugly, Marc Tan
Abstract: An LED driver circuit for controlling direct current supplied to a plurality of serially connected segments of Light Emitting Diodes (LEDs) is disclosed. In one embodiment, the LED driver circuit comprises a self-commutating circuit, which comprises a plurality of current control elements, each current control element having two ends, a first end connected to a different end of each segment along the plurality of serially connected segments of LEDs and a second end connected to a path to ground. The path to ground comprises a sense resistor and the path to ground is shared by the second end of each current control element. Each current control element is coupled to an adjacent current control element by a cross-regulation circuit and controlled by a signal from an adjacent current control element.
Abstract: A switching linear amplifier has a DC-DC converter to increase a low input DC voltage to a first high voltage DC. A high voltage high frequency inverter is coupled to the DC-DC converter to generate high voltage pulses. A multistage voltage multiplier is coupled to the high voltage high frequency inverter to generate a second high voltage DC. A controlled charge and discharge circuit is coupled to the multistage voltage multiplier to drive a capacitive load.
Abstract: This document describes a new op-amp sharing technique for pipeline ADC without memory effect. The key features of this technique are: the usage of negative impedance converter and scaled replica of the op-amp input device to achieve zero error voltage, which in turns achieve low power dissipation due to the removal of the tradeoff between op-amp sharing and memory effect. With this technique much lower operation of pipeline ADC can be achieved for applications of data communications and image signal processing.
Abstract: The invention provides a novel method of transmit beamforming, which allows compact analog implementation of complex digital algorithms without compromising their features. It is aimed to support envelope shaping, apodization, and phase rotation per channel and per firing. Each of three embodiments represents a complete transmit channel driven by pulse-width modulated (PWM) waveforms stored in a conventional sequence memory. PWM signals controls the transmit pulse envelope (shape) by changing the duty cycle of the carrier. Beamformation data are loaded prior to a firing via serial interface. Under the direction of a controller, the circuitry allows high precision (beyond sampling rate) phase rotation of the carrier. It also provides transmit apodization (aperture weighting), which maintains an optimal trade-off among low sidelobe level and widening of the mainlobe. Implementing such an IC, the manufacturing cost of a high-end ultrasound system can be reduced.
Abstract: Systems and methods are disclosed for operating a highly linearized resistance for a switch through use of a bootstrapped features. In one exemplary implementation, there is provided a method and system that implements a method for operating a circuit configured to provide a highly linearized resistance including receiving a signal via a bootstrapped switch, coupling the received signal to a gate if the received signal is high, receiving a signal via a switch control input coupled to a high impedance element. Moreover, the method includes coupling the high impedance element to the gate and turning off the switch via a gate turn off when the gate turn off pulls the gate low.
Type:
Grant
Filed:
June 18, 2012
Date of Patent:
August 4, 2015
Assignee:
Microchip Technology Inc.
Inventors:
Benedict C. K. Choy, James T. Walker, Ming-Yuan Yeh