Abstract- A conventional boost converter has a high power efficient CMOS adaptive controlledboost step-up LED drive implemented in BCD technology. A novel adaptive minimum frequencycontrol provides up to 52v from a single battery 4.5v input supply to ten series connected LEDs atthe output. The proposed control scheme provides an accurate load current while achieving highpower efficiency than conventional fixed on time schemes. TPS40211 and TPS40210are able toswitch between PWM (pulse width modulation) automatically by calculating the feed backs from theinductor and LEDs current. This controller is functional from light to heavy loading situationswhich critical in improvement of power efficiency and battery life-time for high boost ratioapplications in order as provide accurate LED current.Keywords: CMOS (complementary metal oxide-semiconductor), BCD technology, PWM (pulsewidth modulation control),TPS40211 and TPS40210, LED(light emitting diode).I INTRODUCTIONIn Recent Years, wide use of electrical equipment has forced strict demands for electricalutilizing energy and this development is constantly growing. Accordingly, researchers andgovernments worldwide have prepared on renewable energy applications for explanatory naturalenergy consumption and environmental location. Among different renewable energy sources, thephotovoltaic cell and fuel cell have been considering attractive choice. However, without additionalarrangements, the output voltages generated from both sources. Thus, a high step-up dc-dc converteris desired in the power conversion systems corresponding to these two energy sources. In addition tothe mentioned applications, a high step-up dc-dc converter is also required by many industrialapplications, such as high-intensity discharge lamp ballasts for automobile headlamps and batterybackup systems for uninterruptible power supplies. The conventional boost converter can beadvantageous for Step-up applications that do not demand very high voltage gain, mainly due to theresulting low conduction loss and design simplicity. Theoretically, the boost converter static gaintends to be infinite when duty cycle also tends to unity. However, in practical terms, such gain islimited by the I2R loss in the boost inductor due to its intrinsic resistance, leading to the necessity ofaccurate and high-cost drive circuitry for the active switch, mainly because great variations in theduty cycle will affect the output voltage directly.To overcome this disadvantage the TPS40210 and TPS40211 are used. They are the wideinputvoltage (4.5V to 52V), non-synchronous boost controllers. They are suitable for topologieswhich require a grounded source N-channel FET including boost, fly back, SEPIC and various LEDdriver applications. The device features include programmable soft start, over current protection withautomatic retry and programmable oscillator frequency. Current mode control provides improvedtransient response and simplified loop compensation. The main difference between the two parts isthe reference voltage to which the error amplifier regulates the FB pin.II METHODOLOGYTo achieve more efficiency when compare to the existing system nearer to 95%. To reduceswitching loses and power dissipations. To reduce the complex design of the circuit for the externalprocessing units like error amplifier, current and voltage sensing unit, PWM controller unit, currentand voltage regulator, oscillator unit and soft switching unit. To produce the high voltage gain withlow input voltage. To maintain the proper duty cycle. To reduce the power losses in the circuit. Theboost converter system consist of one inductor, capacitor, resistor, controller IC and switch for itsoperation. The one side of the inductor is connected to the input terminal and the another side isconnected between switch and diode meting point. The other side of the diode is connected to thecapacitor. The resistor is connected across the output terminal. The controller IC unit is connectedwith the MOSFET switch for PWM operation and also connected with the another ends of thecapacitor, resistor and positive region of the output terminal to perform the current and voltagelimiting, controlling, regulating operations. The over all control of the circuit is carried out by theTPS40211 OR TPS40210 ICs. The control of the input and output over voltages and over current,error amplification, voltage regulation, fault clearance and duty cycle maintenance all are can bedone using a single IC. So that the design complexity is reduced. The heat losses due to the single ICis low when compare to the conventional method. So that we can able to achieve the 95% efficiency.Fig1. Functional block diagram of boost converterA. Detailed Description Of Functional Block DiagramThe TPS40210 and TPS40211 are high-efficiency LED drivers each featuring an integratedDC-DC inductive boost converter and six high-precision current sinks. TPS40210 is intended forapplications that exclusively use a pulse width modulated (PWM) signal for controlling the brightnesswhile TPS40211 is intended for applications that can utilize an I2C master as well.The boost converter has adaptive output voltage control. This feature minimizes the powerconsumption by adjusting the voltage to the lowest sufficient level under all conditions.The adaptive current sink headroom voltage control scales the headroom voltage with theLED current for optimal system efficiency.The LED string auto-detect function enables use of the same device in systems with 1 to 10LED strings for the maximum design flexibility.Proprietary hybrid PWM plus current mode dimming enables additional system powersavings. Phase shift PWM allows reduced audible noise and smaller boost output capacitors.Flexible CABC support combines brightness level selections based on the PWM input and I2Ccommands.The TPS40210 and TPS40211 feature a full set of features that ensure robust operation ofthe device and external components. The set consists of input under voltage lockout, thermalshutdown, overcurrent protection, overvoltage protection, and LED open and short detection.B. Boost ConverterThe boost converter is defined as the output voltage is always greater than the input voltage.Switched mode supplies can be used for many purposes including DC to DC converters. Often,although a DC supply, such as a battery may be available, its available voltage is not suitable forthe system being supplied. For example, the motors used in driving electric automobiles requiremuch higher voltages, in the region of 500V, than could be supplied by a battery alone. Even ifbanks of batteries were used, the extra weight and space taken up would be too great to bepractical. The answer to this problem is to use fewer batteries and to boost the available DC voltageto the required level by using a boost converter. Another problem with batteries, large or small, isthat 1their output voltage varies as the available charge is used up, and at some point the batteryvoltage becomes too low to power the circuit being supplied. However, if this low output level canbe boosted back up to a useful level again, by using a boost converter, the life of the battery can beextended.The DC input to a boost converter can be from many sources as well as batteries, such asrectified AC from the mains supply, or DC from solar panels, fuel cells, dynamos and DCgenerators. The boost converter is different to the Buck Converter in that it’s output voltage isequal to, or greater than its input voltage. However it is important to remember that, as power (P) =voltage (V) x current (I), if the output voltage is increased, the available output current mustdecrease. MOSFET, both Bipolar power transistors and MOSFETs are used in power switching,the choice being determined by the current, voltage, switching speed and cost considerations. Therest of the components are the same as those used in the buck converterC. TPS40211 AND TPS40210The TPS40210 and TPS40211 are used. They are the wide-input voltage (4.5V to 52V),non-synchronous boost controllers. They are suitable for topologies which require a groundedsource N-channel FET including boost, fly back, SEPIC and various LED driver applications. Thedevice features include programmable soft start, over current protection with automatic retry andprogrammable oscillator frequency. Current mode control provides improved transient response andsimplified loop compensation. The main difference between the two parts is the reference voltage towhich the error amplifier regulates the FB pin.1. CapacitorBoost Input And Vdd Capacitor SelectionThe VDD pin is typically tied to the same supply as the input of the boost power stage (VINnode). A10?F input capacitor is recommended on that node. The voltage rating of the capacitor mustbe at least 10 V. If a supply powering the VDD pin is different from a supply powering the boostpower stage, then 10-?F input capacitors are required on both VDD and VIN nodes.Boost Output Capacitor SelectionThe inductive boost converter typically requires two 4.7-?F output capacitors. The voltagerating of the capacitor must be 35 V or higher as the OVP threshold is at 29.6 V (typ). Pay carefulattention to the capacitor tolerance and DC bias response. For proper operation of the degradation incapacitance due to tolerance, DC bias, and temperature should stay above 2 ?F. This might requireplacing more than two devices in parallel in order to maintain the required output capacitance overthe device operating temperature and output voltage range.2. InductorInductor SelectionThe chosen inductor must be from 10 to 22 ?H (for 500-kHz operation) or 4.7 to 10 ?H (for1-MHz operation) and must have a saturation rating equal to, or greater than, the circuit’s peakoperating current.Performance AnalysisThe main intension of this paper is to design a high efficient boost converter. Hardwareconsists of three main constituent which are the input, adaptive boost converter and the output. Theinput voltage is from the solar panel, the adaptive boost converter function is to get high outputvoltage and to increase the efficiency these can be achieved by using TPS40211, TPS40210,LP8557, LP85571 type ICs. These types of ICs are multitasking devices so that they can act like aregulator for the output voltages and currents, error amplifier, disable and enable operator, softswitcher, switching frequency manager, current and voltage sensor, high output gain producer andduty cycle maintenance operator. These all controlling processes can be done in a single IC. So thatthe circuit complex can be reduced, losses also reduced, efficiency can be obtained is high and theoutput voltage is used to glow the LEDs. The boost DC-DC converter generates a 50V to 52V boostoutput voltage from a 4.2V to 4.5-V boost input voltage. The converter is a magnetic switchingPWM mode DC-DC inductive boost converter with a current limit. It uses current programmed modecontrol, where the inductor current is measured and controlled with the feedback. During start-up,the soft-start function reduces the peak inductor current.III SIMULATION RESULTSThe fully integrated LED driver circuit is functional for LED currents up to 50 mA at lowinput supply voltages (3.0 V to 5.5 V). The LED driver with PWM & PFM controllers is fullyfunctional in the 40 V process of 0.25 ?m BCD technology, as shown by the simulated gate-drive,inductor current, LED current and output voltage waveforms presented in Fig. 2 and Fig. 3.Fig.2 Simulated gate-drive, inductor current, led current (50 mA) and output voltage waveforms of the proposedPWM modeFig.3 Simulated gate-drive, inductor current, led current (16 mA) and output voltage waveforms of the proposed PFMmodeV(gate) is the gate drive signal of power MOSFET M1. I(L) and I(LED) are the inductorcurrent and the LED current, respectively. V(boost) is the boost converter output voltage. In Fig. 2,the converter is operating at constant 1 MHz PWM mode. Ripple peak-peak of the output LEDcurrent is 1.34%. In Fig. 3, the controller operating frequency is not constant and is around 250 kHz.Ripple peak-peak of the output LED current in PFM mode is 2.75%.Output Voltage Vs Load CurrentILOAD – Load Current – AFig.4 The Graph Between Vout And Iload0 0.5 1.0 1.5 2.0 2.5VIN =14 VVIN =8 V14128VIN (V)VIN =12 V24.34024.48424.82024.72424.58024.38824.67624.43624.53224.62824.772Output Voltage VoutFig.6 Efficiency of 10 LED stringThe efficiency of the proposed PWM/PFM controller has been measured when the LEDcurrent is changing from 3mA to 50 mA. The controller switches between PWM and PFM modesautomatically with the changes of the LED current. The averaged efficiency of the converter is 86%.This boost LED driver provides up to 32 V from a single battery (3.6 V to 5.5 V) input supply to 10series-connected LEDs at the output, 30mA is the switchover point between PFM mode and PWMmode. PFM acquires high efficiency when the LED current is less than 30mA. PWM acquires highefficiency when the LED current is larger than 30mA. The combination modulation of PWM andPFM realizes constant high power efficiency in a wide range of LED currents.IV CONCLUSIONSA novel combination of PWM and PFM controlled boost converter is proposed, designed,and simulated in 0.25 ?m BCD technology. The converter provides up to 32 V from a 3.6 V to 5.5V input supply for 10 serial LEDs at the output. To obtain the best power management efficiency,the controller switches between PWM mode and PFM mode automatically as the LED currentchanges. The averaged efficiency of the converter is 86% when the LED current is on the range of 3REFERENCES1. C. Richardson.”Driving high-power LEDs in series-parallel arrays”,National Semiconductor, Santa Clara, CA, 2008.2. R. Erickson and D. Maksimovic, High efficiency, dc-dc converters for battery operated systems with energymanagement, Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder .3. L. Zhu and F. Quanyuan, “Design of PWM controller for monolithic boost converter,” 7th InternationalConference on ASIC, pp. 660-663, 20074. B. Sahu and G.A. Rincon-Mora, “An Accurate, Low-Voltage, CMOS Switching Power Supply with Adaptive On-Time Pulse-Frequency Modulation (PFM) Control,” IEEE Transactions on Circuits and Systems, Volume 54,Issue 2, Feb. 2007 pp: 312 – 3215. C.H. Chang, H. M. Chen, and R.C. Chang, “A 2.3 V CMOS Monolithic, 84% Efficiency PFM Control DC-DCBoost Converter for White LEDs Driver IC,” PEDS 2005, pp. 833 – 8376. Y. Fang, Siu-Hong Wong and L. Hok-Sun Ling, “A Power converter with pulse-level-modulation control fordriving high brightness LEDs”, Proc. Twenty-Fourth Annual IEEE Applied Power Electronics Conference andExposition APEC, 2009, pp. 577-5817. H.V.D. Broeck, G. Sauerlander, and M. Wendt, “Power driver topologies and control schemes for LEDs”, AppliedPower Electronics Conf. (APEC2007), Mar. 2007, pp. 1319-13258. S. M. Baddela, D. S. Zinger, “Parallel connected LEDs operated at high frequency to improve current sharing” IASConference, 2004. 39th IAS Annual Meeting. Conf. Rec. of the 2004 IEEE Vol. 3, 3-7 Oct. 2004 pp: 1677-1681.