A High Efficiency Step-Up WLED Driver with Wide Range PWM Dimming

2012 ◽  
Vol 588-589 ◽  
pp. 884-887
Author(s):  
Fei Xu ◽  
Le Nian He
Keyword(s):  
Pulse Width Modulation ◽  
High Efficiency ◽  
Light Emitting Diode ◽  
System Efficiency ◽  
Current Sensing ◽  
Light Emitting ◽  
Wide Range ◽  
Simulation Results ◽  
Peak Value ◽  
Pwm Dimming

A high efficiency step-up White Light Emitting-diode (WLED) driver with PWM dimming is presented in this paper. An integrated current sensing technique is used to improve system efficiency. Meanwhile, a novel PWM(pulse width modulation) dimming scheme is proposed to achieve wide range dimming frequency, which can be adaptive to dimming frequency from 200Hz to 200 KHz. The proposed driver is designed with CSMC 0.5um 40V bipolar-CMOS-DMOS process. Simulation results verify the functionality of the design and high efficiency is realized, with a peak value of 94.12% at 5.5V-input and 200mA-load.

scholarly journals LED Rail Signals: Full Hardware Realization of Apparatus with Independent Intensity by Temperature Changes

Electronics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1291
Author(s):  
Giuseppe Schirripa Schirripa Spagnolo ◽  
Fabio Leccese
Keyword(s):  
Temperature Sensor ◽  
Energy Efficient ◽  
Light Emitting Diode ◽  
Junction Temperature ◽  
Light Emitting ◽  
Temperature Changes ◽  
Wide Range ◽  
International Regulations ◽  
Long Lifetime ◽  
Set Up

Nowadays, signal lights are made using light-emitting diode arrays (LEDs). These devices are extremely energy efficient and have a very long lifetime. Unfortunately, especially for yellow/amber LEDs, the intensity of the light is closely related to the junction temperature. This makes it difficult to design signal lights to be used in naval, road, railway, and aeronautical sectors, capable of fully respecting national and international regulations. Furthermore, the limitations prescribed by the standards must be respected in a wide range of temperature variations. In other words, in the signaling apparatuses, a system that varies the light intensity emitted according to the operating temperature is useful/necessary. In this paper, we propose a simple and effective solution. In order to adjust the intensity of the light emitted by the LEDs, we use an LED identical to those used to emit light as a temperature sensor. The proposed system was created and tested in the laboratory. As the same device as the ones to be controlled is used as the temperature sensor, the system is very stable and easy to set up.

A high-power PCCM LED driver based on GaN eHEMT with hybrid dimming modes

Circuit World ◽  
2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xixian Lin ◽  
Yuming Zhang ◽  
Yimeng Zhang ◽  
Guangjian Rong
Keyword(s):  
Printed Circuit Board ◽  
Pulse Width Modulation ◽  
Circuit Board ◽  
Switching Frequency ◽  
Led Driver ◽  
Power Circuit ◽  
Content Type ◽  
Wide Range ◽  
Circuit Function ◽  
Pwm Dimming

Purpose The purpose of this study is to design a more flexible and larger range of the dimming circuit that achieves the independence of multiple LED strings drive and can time-multiplex the power circuit. Design/methodology/approach The state-space method is used to model the BUCK circuit working in Pseudo continuous conduction mode, analyze the frequency characteristics of the system transfer function and design the compensation network. Build a simulation platform on the Orcad PSPICE platform and verify the function of the designed circuit through the simulation results. Use Altium Designer 16 to draw the printed circuit board, complete the welding of various components and use the oscilloscope, direct current (DC) power supply and a signal generator to verify the circuit function. Findings A prototype of the proposed LED driver is fabricated and tested. The measurement results show that the switching frequency can be increased to 1 MHz, Power inductance is 2.2 µH, which is smaller than current research. The dimming ratio can be set from 10% to 100%. The proposed LED driver can output more than 48 W and achieve a peak conversion efficiency of 91%. Originality/value The proposed LED driver adopts pulse width modulation (PWM) dimming at a lower dimming ratio and adopts DC dimming at a larger dimming ratio to realize switching PWM dimming to analog dimming. The control strategy can be more precise and have a wide range of dimming.

High‐Efficiency Top‐Emitting Green Perovskite Light Emitting Diode with Quasi Lambertian Emission

2021 ◽  
pp. 2101137
Author(s):  
Lei Cai ◽  
Jungui Zhou ◽  
Guilin Bai ◽  
Jiaqing Zang ◽  
Abdelhamid El‐Shaer ◽  
...  
Keyword(s):  
High Efficiency ◽  
Light Emitting Diode ◽  
Light Emitting

High efficiency AlGaInN-based light emitting diode in the 360–380 nm wavelength range

2003 ◽  
Vol 200 (1) ◽  
pp. 102-105 ◽  
Author(s):  
Hisao Sato ◽  
Hong-Xing Wang ◽  
Daisuke Sato ◽  
Ryohei Takaki ◽  
Naoki Wada ◽  
...  
Keyword(s):  
Wavelength Range ◽  
High Efficiency ◽  
Light Emitting Diode ◽  
Light Emitting

scholarly journals High-Efficiency Monolayer Molybdenum Ditelluride Light-Emitting Diode and Photodetector

2018 ◽  
Vol 10 (50) ◽  
pp. 43291-43298 ◽  
Author(s):  
Yi Zhu ◽  
Ziyuan Li ◽  
Linglong Zhang ◽  
Bowen Wang ◽  
Zhenqing Luo ◽  
...  
Keyword(s):  
High Efficiency ◽  
Light Emitting Diode ◽  
Light Emitting

scholarly journals Use of Hybrid PEDOT:PSS/Metal Sulfide Quantum Dots for a Hole Injection Layer in Highly Efficient Green Phosphorescent Organic Light-Emitting Diodes

2021 ◽  
Vol 9 ◽  
Author(s):  
Wenqing Zhu ◽  
Kuangyu Ding ◽  
Chen Yi ◽  
Ruilin Chen ◽  
Bin Wei ◽  
...  
Keyword(s):  
Quantum Dots ◽  
High Efficiency ◽  
Light Emitting Diode ◽  
Metal Sulfide ◽  
Molybdenum Sulfide ◽  
Hole Injection ◽  
Light Emitting ◽  
Hole Injection Layer ◽  
Highly Efficient ◽  
Organic Light

In this study, we have synthesized the molybdenum sulfide quantum dots (MoS2 QDs) and zinc sulfide quantum dots (ZnS QDs) and demonstrated a highly efficient green phosphorescent organic light-emitting diode (OLED) with hybrid poly (3,4-ethylenedioxythiophene)/poly (styrenesulfonate) (PEDOT:PSS)/QDs hole injection layer (HIL). The electroluminescent properties of PEDOT:PSS and hybrid HIL based devices were explored. An optimized OLED based on the PEDOT:PSS/MoS2 QDs HIL exhibited maximum current efficiency (CE) of 72.7 cd A−1, which shows a 28.2% enhancement as compared to counterpart with single PEDOT:PSS HIL. The higher device performance of OLED with hybrid HIL can be attributed to the enhanced hole injection capacity and balanced charge carrier transportation in the OLED devices. The above analysis illustrates an alternative way to fabricate the high efficiency OLEDs with sulfide quantum dots as a HIL.

A high-efficiency hybrid white organic light-emitting diode enabled by a new blue fluorophor

2015 ◽  
Vol 3 (17) ◽  
pp. 4283-4289 ◽  
Author(s):  
Zhan Chen ◽  
Xiao-Ke Liu ◽  
Cai-Jun Zheng ◽  
Jun Ye ◽  
Xin-Yang Li ◽  
...  
Keyword(s):  
High Efficiency ◽  
Light Emitting Diode ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Organic Light

High-efficiency hybrid white organic light-emitting diode enabled by a new blue fluorophor.

High efficiency Green Organic Light-emitting Diode Without Roll-off Under High Current Density

2015 ◽  
Vol 36 (11) ◽  
pp. 1307-1310
Author(s):  
田苗苗 TIAN Miao-miao ◽  
贺小光 HE Xiao-guang ◽  
祁金刚 QI Jin-gang ◽  
王 宁 Wang Ning
Keyword(s):  
Current Density ◽  
High Efficiency ◽  
High Current Density ◽  
Light Emitting Diode ◽  
High Current ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Organic Light
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