Light & Engineering Vol. 23, No. 3, pp. 78-84, 2015 Svetotekhnika No. 4, 2015, pp. 59-63 COMPARISON OF A SINGLE PHASE LINEAR AND A BUCK-BOOST LED DRIVER Erdal Şehirli, Meral Altınay, and Bekir Зakır Kastamonu University and Kocaeli University E-mails: esehirli@kastamonu.edu.tr; meral.altinay@kocaeli.edu.tr; bcakir@kocaeli.edu.tr ABSTRACTS This paper presents a comparison of LED driver topologies that include linear and buck-boost converters. <...> Both topologies are connected to grid over a single-phase diode rectifi er and designed for 8 W power. <...> Finally, power factor and total harmonic distortion (THD) of current and voltage, power LED voltage and current are shown for both topologies over implementations, and a comparison is made. <...> Furthermore, voltage-current characteristic, current and voltage- illuminance characteristics are derived. <...> Keywords: LED driver, single phase buck-boost converter, linear regulator, power factor, THD 1. <...> INTRODUCTION The power LEDs using in lighting is more common nowadays and receives much attention due to their high effi ciency. <...> Besides, power LEDs need dc power in order to operate, and obtaining dc power is possible using a battery, solar cells and grid. <...> To use a single-phase grid for dc voltage, rectifi er circuits are needed. <...> After rectifi cation, linear and switch mode topologies are used to obtain vari able dc voltage feeding power LEDs. <...> However, a diode rectifi er can effect the grid negatively in terms of power factor and THD. <...> Furthermore, using a dc-dc converter after uncontrolled LED single phase rectifi er can avoids these problems. <...> That’s why this kind of converters is called as power factor corrected (PFC) converters. <...> Especially, operating buck-boost derived topology at DCM can reduce switching losses and for power factor correction, buck-boost converter is the most appropriate converter. <...> In paper [6] ac-dc and dc-dc converters are used as an LED driver. <...> Advantages and disadvantages of basic dc-dc converter using as PFC converters are analysed as in [8–10]. <...> In [11], designs, analyses and ope ration of dc-dc converters are describing <...>