LED Drivers for LED Systems

Formative Performance of LED Systems

An LED driver is an electrical device that regulates the power to an LED as its electrical properties change with temperature. A key characteristic of any constant current LED driver is its efficiency. Efficiency gives us the amount of input power that can actually be used by the driver, to power the LED. With the fast development of LED technology the need for energy – efficient lighting solution is increasing significantly across the globe. This results in several innovations in LEDs & LED drivers’ field. This article is a concrete study brings to you some of these innovations…

The long life spans and energy savings factors have became a common factor associated with LEDs, along with specialized devices called LED drivers to operate. LED drivers provide LEDs with the electricity they require to function and perform at their best.

Combined with right drivers LEDs & LED based systems not only delivers desired performance but Smart lighting set-ups can be made. LED drivers are available from major semiconductors companies across the world. In the international market, Texas Instruments (TI) LED driver IC has the highest visibility. European and U.S. companies including NXP, Marvell and others have also launched LED driver IC. Asian IC design companies’ optimistic outlook of future developments has led to their active entry into the LED market in 2013. IC design companies including Macroblock, Richtek Technology Corp., On-Bright Electronics Co., Silergy Corp., and Champion Microelectronic Corp. all have plans of entering this market.

Out of the box applications of LEDs achieved the drivers:

The range of the LEDs available in market is much diversified, but to use LED as a raw material for a given application, for ex. mobile flash light, a specified LED is required with dedicated electronics associated. The fact simply illustrated the importance of drivers in a given LED based system and proves, “a suitable driver leads a simple LED to an innovation application.” Some of the breakthrough in the LED based applications is as follows:

1. LED Signage: ICs used are, Multi-channel constant-current LED String control products.
2. Backlight applications: DC/DC LED drivers with innovative dimming control for backlighting LCD panels.

• Camera Flash Lights: Flash drive solutions

1. Indicator/RGBW Lights: Power regulating drivers
2. Automotive Lighting: DC/DC and Linear LED drivers.

Streamlined wireless connected lighting system from Philips

Philips Advance Xitanium SR LED Driver provides foundation for connected lighting systems. Philips Advance Xitanium SR LED Drivers standardize the digital connection between the driver and sensor to eliminate the need for multiple separate components and alleviate incompatibility issues and time consuming configurations.

Choosing an LED Driver

In today’s fast-paced and rapidly-changing LED arena, the complex and subtle choices involved in choosing an LED or LED array can be difficult enough. Add to this the confusion of selecting an LED driver in a SSL industry marked by obscure terminology where even the experts’ still debate definitions and standards, and the task can be overwhelming. Lets us explore some of the factors deciding LED drivers.

Constant voltage or current

Constant-voltage drivers power LEDs that require a fixed output voltage with a maximum output current. In these LEDs, the current is already regulated, either by simple resistors or an internal constant-current driver, within the LED module. These LEDs require one stable voltage, usually 12V DC or 24V DC. In the example below to the right, the output voltage is 24V DC, and the output current is a maximum of 1.04A.

AC LED drivers are actually no-minimum load transformers, meaning they could technically operate low-voltage halogen or incandescent bulbs as well. LEDs, however, cannot operate with conventional transformers because conventional transformers were not made to detect the low wattage of LEDs. AC LED drivers are typically used with bulbs that already contain an internal driver that converts the current from AC to DC, so an AC LED driver’s job is to register the low wattage of LEDs and step down the voltage to meet the bulb’s voltage requirements, usually 12 or 24 volts. AC LED drivers are typically used to power 12-24V AC input LED MR16 bulbs, but they can be used for any 12- 24V AC input LED bulb. The LED bulb datasheet must be carefully examined; if the LED bulb requires DC voltage input, it cannot be used with an AC LED driver.

LED Drivers makes LED Lighting – Smart Lighting

Energy saving is one of the major concerns for state and national governments globally. Loss of energy through lighting has become national concern for governments. Smart lighting is a new innovation in lighting technology that is developed for energy efficiency. This technology may include efficiency fixtures and automated controls lighting system that make adjustments according to conditions and requirements of the internal or external environment such as occupancy or availability of daylight. Lighting accounts for 20% to 50% of the global consumption of energy. It is essential to use limited electric energy to reduce energy consumption. Market players have been introducing innovative lighting systems that help conserve energy. Smart lighting is a technology that uses intelligent light control system. Factors such as object movement, occupancy, color, temperature and availability of natural light helps smart lighting technology to perform efficiently. This technology uses lighting control systems that deliver the required amount of light optimally. Smart lighting also entails technology that automatically performs various functions at a set time and under a given condition. Smart lighting technology provides highly flexible lighting at low energy consumption and cost.

Europe accounts for the largest market share for smart lighting technology, followed by North America and Asia Pacific. The U.S. is the largest consumer of smart lighting technology, led by increasing consumer awareness about the importance of energy saving. Europe is likely to maintain its dominance in smart lighting technology, while North America is anticipated to experience marginal growth during the forecast period. However, Asia Pacific is expected to witness the highest growth during the forecast period, due to rapid growth in infrastructure development in developing countries such as India and China.

Light manufacturing companies are compelled to introduce innovative lighting technology, especially in developing regions, due to rising demand and higher spending capacity for energy saving equipment by major end-users. Major companies operating in the global smart lighting technology market are Zumtobel AG, Lutron Electronics Company, Inc., Digital Lumens, Inc., Encelium Technologies, Inc., Legrand S.A., Acuity Brands, Inc., Honeywell International, Royal Philips Electronics N.V. and Osram Light AG.

Mr. Steve Kennelly, Senior Manager, MCU8 Marketing, Microchip Inc.

For LED applications, our focus is on specialized peripherals that are integrated on our MCUs to provide functions such as current regulation, dimming, communication and system monitoring with minimal software or CPU intervention.

Mr. Kennelly from Microchip Inc. shares his views with us about the driver segment of LED systems. As per Mr. Steve, LED-based lighting systems are very different from other types of lights. One of the big differences is the need for a driver in LED systems. Microchip offers practical, efficient and cost-effective innovations for the designers of LED-lighting applications. For incandescent-replacement and other cost-sensitive systems with simple functionality, our broad range of dedicated LED drivers enables the realization of LED luminaries with a minimum of external components. Higher-featured systems can use our PIC® microcontrollers to implement lighting control and communication strategies, as well as digital power conversion for constant current drive. For these applications, our focus is on specialized peripherals that are integrated on our microcontrollers (MCUs) to provide functions such as current regulation, dimming, communication and system monitoring with minimal software or CPU intervention. Our device innovations give lighting designers the freedom to create new LED-based systems. Discussion about technological core – competencies, Mr. Steve stated energy efficiency is one of Microchip’s main goals and one of our core competencies. LED-lighting systems are inherently more energy efficient than incandescent or fluorescent designs. Taking full advantage of this efficiency requires the driver to be as efficient as possible. Our previously mentioned analog drivers and PIC MCUs are highly optimized to enable the most efficient systems. Additional efficiency gains are possible with LED systems, by including advanced control features such as occupancy detection, daylight harvesting, task-based dimming and load leveling. Microchip’s PIC MCUs include the sensor and communication interfaces, processing power and analog integration to enable these features and more.

Further Mr. Steve talked about Smart Lighting Concept. Smart lighting can include various features. As mentioned before, advanced controls are an important part of smart-lighting systems. By using sensors to detect and measure ambient light, temperature, the presence of people, color and other things, PIC MCU-based lighting systems can adapt to changing conditions and needs. The brightness and color of light can be adjusted to create a mood or to support a given task, while also reducing power consumption. Microchip’s gesture and touch sensing technologies enable the development of innovative and intuitive user interfaces, enabling lighting system designers create new and differentiated products. A smart-lighting system with user-friendly controls not only saves energy, but also improves employee productivity and increases customer satisfaction. Microchip’s PIC MCUs also support a number of communication protocols, to create networked lighting systems. DALI, DMX512, ZigBee® and Ethernet are among the standards available in our libraries. Networked lighting systems allow centralized monitoring and control, combined with distributed sensing, to maximize the benefits of a smart-lighting system.

Mr. Ulrich Vom Bauer, Senior Manager Marketing .dp digital power 2.0, Power Management & Multimarket Division, Infineon Technologies AG

To best address the widest number of market opportunities, fixture designers need to shorten development cycles, by the emergence of simple and easy-to-integrate LED and power modules that reduce the level of complexity in design.

Mr. Bauer, joined us on this technological story and express his views from the technological perspective as, the accelerating transition to LED-based lighting is changing the dynamics of luminaries design. The first trend is the emergence of many new competitors, concurrent with rapidly falling prices for LEDs. While LEDs historically represented a large portion of a fixtures’ cost, other electronic components – including driver, power stage ICs and LED protection devices – are becoming a more significant portion of the overall BOM. And of course, there is relentless pressure to reduce the total end product cost. Lastly, as LED-based luminaries become pervasive across multiple segments and different lighting sub-applications, there is enormous pressure to simplify the design process. To best address the widest number of market opportunities, fixture designers need to shorten development cycles. This is addressed by the emergence of simple and easy-to-integrate LED and power modules that reduce the level of complexity in design of the lighting element. The flexibility to drive LEDs at different drive currents and different configurations, thus forming luminaries in different shapes and sizes than possible with traditional light sources, provides an opportunity for disruptive innovation in lighting. Yet this flexibility poses unique challenges for driver design. Until some level of standardization takes hold, each individual design requires custom drivers. The relative immaturity of control schemes related to dimming and other feature requirements can make driver design overly complicated and expensive. The application itself poses several challenges, whether it is outdoor wall-washing lights, or indoor down-light solutions driven from AC mains or from a DC bus or power-supply. With these concerns in mind Infineon has developed the .dp digital power 2.0 generation of digital and intelligent LED driver ICs to be used in combination with state-of-the art power stages. dp digital power 2.0 will be introduced to the broader market by 2015.

Another major trend affecting the industry is the increased demand for energy efficiency. This is best addressed by a system level approach and not by focusing solely on component selection. To respond to the efficiency challenge, the on-going migration to digital control of driver ICs and power stages for LEDs provides fixture designers with much greater ability to optimize power conversion. Since the regulatory hurdles have been raised by authorities in many countries the defined future energy requirements cannot be met anymore by conventional analogue power designs. For this reason a shift to digital power design is a must not only for innovation driven companies but for all key players. Up today Infineon has been the market leader in power technologies for more than ten consecutive years. In order to further strengthen our leading position in the market we entered the digital power world already some years ago. Combining it with our deep knowledge of analogue power technologies and developing it even further. The merging of these two worlds resulted in .dp digital power 2.0.

Talking about Smart lighting, he stated that, LED lighting offers new smart lighting opportunities. This is due to the fact that LEDs are the first light sources that actually extend their lifetime when they are switched on and off frequently. Furthermore, compared to other light sources they generate higher energy savings when dimmed. Yet another benefit is that electronics are an integral part of LED luminaries and can easily be connected to lighting control systems. Smart lighting features can be implemented in decentralized or centralized control systems. When used with centralized control systems, different wired or wireless communication systems are used. Microcontrollers and sensors are key components for enabling smart lighting. The Infineon XMC1000 product family integrates the ARM® Cortex™-M0 core into a leading-edge 65nm manufacturing process in order to overcome the limitations of contemporary 8-bit designs. The XMC1000 offers current 8-bit users a new opportunity to enjoy 32‑bit power, without having to compromise on price or ease of use. The XMC1200 line features dedicated peripherals for LED lighting designs. Thanks to their Brightness and Color Control Unit (BCCU), XMC1000 products offer a unique module for automatically controlling the dimming level and color of multichannel LED lamps. Users can quickly configure their ideal solution without the need for an expert knowledge of lighting. Furthermore, XMC1000 products can also be used as DALI or DMX512 slaves and therefore comply with standard lighting communication protocols. DAVE™ Apps are available for both standards. A lot of energy is currently wasted due to illuminated areas where nobody is present. Passive infrared (PIR) is a simple way of detecting presence. However, passive infrared sensors are not suited for presence detection in big areas such as warehouses, factories and in outdoor weather conditions. Compared to infrared, radar solutions from Infineon can cover areas about 10 times larger.A further key advantage of microwave 24GHz radar solutions for presence detection is their fine resolution in detecting and discriminating the motion of small objects, along with the direction and speed of objects. Microwave radar precision also enables the location of individuals to be determined. Infineon offers a 24GHz Radar Demonstrator Kit based on the radar transceiver BGT24MTR11 in combination with the microcontroller XMC4500, along with a second kit using BGT24MTR12 together with the microcontroller XMC4400 developed by System Design House partners. The radar sensor solution based on the BGT24Mxx 24GHz ISM Band Radar Transceiver Family saves around 30% board space compared to discrete line-ups. This is due to the fact that it offers the highest level of integration currently available on the market.

Mr. Shinu.V. Mathew – Analog Application Engineer, Texas Instruments India

Texas Instruments offers a broad suite of microcontroller based and standalone solutions for LED and other lighting design and control needs.

Mr. Mathew stated that, in the present realm consisting of diverse markets and applications, TI offers innovation in the LED lighting segment. These lighting solutions aim at significantly reducing costs while ensuring improvement in the performance of the system, thereby helping use of available electricity in a more efficient manner. TI has LED drivers and solutions, an award winning initiative in this segment, which focuses on enabling lighting developers, having the flexibility to enhance designs to meet the ever growing demands of this evolving market. With the help of its broad and deep product offerings, TI covers the entire range of products in LED driver. TI has introduced their latest solutions in forms of devices such as Bulbs, Tube-lights, and Down-lighters (TPS92310/1) product range. Also, to cater to high wattage, products such as TPS92210, TPS92020, LM3464, etc have been introduced. TI also offers a broad range of solutions for solar based LED lighting (TPS61165, LM3401, TPS40211, etc). TI has also come up with their recent innovations in the field of Camera Flash LED Drivers offering products such as LM3648, LM3643 and LM3644. TI has also introduced TRIAC dimmable offline LED driver solution which is perfect for any application where an LED driver must interface to a standard TRIAC wall dimmer. The product segment of LED driver ensures high adjustability despite a small solution size.   TPS92411x is a floating switch for Offline AC Linear Direct Drive of LEDs. This is a high-performance solution for driving LEDs from AC Mains which simplifies design of phase dimmable LED Driver with High Power Factor, Low Total Harmonic and suitable for LED Luminaries up to 70+ W. The TPS92411 is a 100-V floating MOSFET switch for use in offline LED lighting applications. The device is used in conjunction with a current regulator that can achieve a power factor greater than 0.9 to create a LED drive solution with low-ripple current. When properly designed, solution performance is comparable to traditional flyback, buck or boost-based AC/DC LED drivers. The approach requires no inductive components, thus saving size and cost. Slew-controlled low-frequency operation of the TPS92411 switches creates very little EMI. This high-performance solution can drive LEDs from AC Mains which simplifies design of phase dimmable LED Driver with High Power Factor, Low Total Harmonic and are suitable for LED Luminaries up to 70+ W. Along with TPS92410 this solution can drive high-brightness light emitting diodes (LEDs) with features a wide input voltage range (9.5 V to 400 V), thermal fold-back, analog dimming capability, and linear FET overvoltage protection. In Automotive Lighting, TI is changing the way LED Lighting solutions are being implemented, right from LED Headlights to Indoor Mood Lighting. For instance, TI’s TPS92661-Q1 is Industry’s first fully integrated LED matrix manager for adaptive automotive headlight systems. This solution is helping Car OEMs and Tier1 vendors develop LED Headlight systems with Beam forming capabilities, an important feature for passenger convenience and safety.

Where lighting solutions of LED Systems is concerned, TI sets a new benchmark with respect to integration, performance, features, and total system cost. Today, maximum integration is possible through the latest technology and solutions, to make it more cost effective and of a lesser board size. TI’s LED drivers and solutions give lighting developers the flexibility to optimize their designs to satisfy the demanding challenges of this dynamic market. For aiming at implementing connectivity solutions in LED Luminaries, CC2541-BLE SOC and CC2530-2.4 GHZ Zigbee SOC are some of the TI parts. TI’s new TRIAC dimmable LED driver delivers a wide, uniform dimming range free of flicker, best-in-class dimming performance and high efficiency, all while maintaining ENERGY STAR® power factor requirements in a typical application. TI’s digital Ambient Light sensing devices help customers implement self-dimmable Lighting solutions thereby making them as efficient as they can get.

Smart lighting is the ability to reduce the amount of light and/or energy used so that only the right amount of light is delivered exactly where it is needed. Smartly controlled lighting using microcontrollers (MCUs) allows taking advantage of the unique characteristics of LEDs to develop efficient, scalable and flexible designs for intelligent lighting. With digital control, designers can scale and easily adjust designs to multiple applications, maximizing reuse and decreasing design time. A digital approach also allows many hardware features, such as soft startup, delay and PWM phase shifting, to be implemented in software, eliminating extra components, cost and complexity. TI’s communications and control solutions are for both wired and wireless systems supporting a wide selection of communication standards.

Digital communications can be achieved via wired or wireless communications through a number of different communication standards including 6LoWPAN and power line communications .Smart TI solutions support industry-standard communications like Power line communications (PLC), DALI, DMX512, ZigBee®, 6LoWPAN, and many others. Design flexibility and scalability ensures maximum reuse of designs and cost management. Intelligent lighting management enables high efficiency, control of smarter light fixtures to handle lumen maintenance to improve reliability and lifetime of LEDs. TI’s C2000™ and Piccolo™ real-time MCUs can perform all power management functions needed in a lighting product, giving flexibility for regional products or quick design spins. MCUs have a low-cost adder for additional LED strings, a high-dimming ratio of greater than 20,0000:1 and a high PWM-dimming frequency of >100KHz.

Conclusion

The global LED driver IC market saw old manufacturers expanding, and new manufacturers dividing market share in 2013. Due to strong demands for LED bulbs and LED tubes, many manufacturers are competing in AC to DC and DC to DC sectors of the LED IC driver market. But the challenge is to meet next-generations demand and present ground-breaking solutions to the consumers. Smart lighting is knocking the door of Indian lighting scene and very soon we may see conceptual way-outs in our surrounding in residential, commercial and industrial lightings.