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This paper presents a method of improving power conversion efficiency of a boost LED driver circuit for edge-lit LED Backlight Units. The proposed circuit consists of a conventional boost converter and a new passive snubber circuit which consists of an inductor, two capacitors, and two diodes; it improves the problems relating to a high voltage gain and hard switching of the boost LED driver. The...
This paper proposes a single-stage driver for highpower light-emitting diodes (LEDs). The presented circuit combines an active power-factor-correction (PFC) converter with a half-bridge-type LLC resonant converter. The active PFC converter consists of two boost-converted cells to achieve input current shaping with interleaving methods. The halfbridge-type LLC resonant converter is designed for obtaining...
This paper presents a highly efficient switched capacitor (SC) DC-DC converter, which is implemented in a 65nm low power CMOS process to enable SoC integration. The converter supplies a nominal output current of 30mA with an efficiency of 95%. The buck converter operates with a constant input voltage of 1.83V and produces an output voltage of 1.2V. The charge is transported in two phases from the...
This paper deals with a construction and practical testing of a VU meter driver that includes an accurate rectifier and logarithmic driver of a pointer-type gauge. The logarithm is taken from the rectified signal by employing a capacitor discharge voltage curve. The appropriate circuit was built and tested and the results are also discussed in this article.
The electroluminescent lamps became more and more used in automotive industry and also in advertising industry domain or as backlight for LCD's. An electroluminescent lamp is basically a capacitor that contains a phosphor layer located between conductive layers that form the plates. With increasing field strength the phosphor absorbs energy and produces light. One of the capacitor electrodes is transparent...
This paper describes a patent-pending passive offline LED driver that has no semiconductor switches, electrolytic capacitors, auxiliary power supply and control board. It can provide a fairly smooth current from the ac mains to drive LED strings. The new circuit has the advantages of high input power factor, high energy efficiency and luminous efficacy, long lifetime, stable luminous output and high...
In this paper, we study the feasibility of a single-stage LED driver. The operating principles and design considerations for the LED driver in this study are analyzed and discussed in detail. A laboratory prototype has been built and tested. Using the prototype, high efficiency, high power factor and LED current control were achieved using a wide AC input voltage range from 90 V to 270 V.
This paper presents a preliminary work on a resonant circuit, also called AC-dipole. The resonance frequency of the circuit is changed by the mean of a variable capacitor connecting an inductor. For this purpose, a bank of switched capacitors of different values are connected to the main circuit through bidirectional switches. An experimental validation of the principle is performed on a resonant...
Certain CCFL driver topologies produce an asymmetrical output voltage which causes migration of the mercury to one side of the CCFL tube. It is known that a DC voltage component across the CCFL leads to this effect. However, even when no DC component is present across the lamp, migration takes place if the voltage is asymmetrical. Eventually, in the absence of a series ballast capacitor, a DC current...
This paper presents a low-ripple regulated charge pump with continuous pumping current control. Output voltage is continuously regulated for full-range load variation. Multi-phase charge pump can be easily achieved under the constant pumping frequency control scheme. In this way, the output voltage ripple can be minimized further. An experimental chip has been fabricated in a 0.5 mum CMOS process...
Since the very beginning of the flash memory era, the market has been dominated by the floating gate technology. However, as floating gate flash continues along a very steep scaling path, more and more barriers start to appear, limiting further scaling possibilities of the technology. At the same time, other concepts are preparing to take over. This paper concentrates on the prospect of high-k materials...
Flux Compression Generators (FCGs) are some of the most attractive sources of single-use compact pulsed power available today due to their high energy density output and mobility. Driving FCGs requires some seed energy, which is typically provided by applying a high seed current, usually in the kilo-Ampere range for mid-sized helical FCGs. This initial current is supplied by a high-current seed source...
The subject of this paper is a fully integrated chargepump circuit with a very low output voltage ripple. At a supply voltage of 30V the chargepump can source 1mA at an output voltage of 40V. Two simple modifications to the classical chargepump circuit give a substantial reduction of the output voltage ripple.
The device described in this paper is a new quad line driver to be used in the hostile and noisy industrial environment and developed in mixed technology (BCD: Bipolar, Cmos, Dmos). It consists of four independent line drivers, each of which has a rail-to-rail push-pull output stage realized with power DMOS transistors connected in half bridge configuration. Even though the device is designed to be...
A novel single-channel MOS amplifier stage for sampled-data applications is proposed. It features low power consumption, small area occupation and high gain at low frequencies. The operating principle and elementary theory are presented together with experimental results on a preliminary realization.
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