ID A17C: Powering, Driving and Dimming High Brightness LEDs with Renesas Lighting Microcontrollers

Transcription

1 ID A17C: Powering, Driving and Dimming High Brightness LEDs with Renesas Lighting Microcontrollers Renesas Electronics America Inc. John Pocs Staff Applications Engineer 13 October 2010 Version: 1.1 1

2 John Pocs Staff Applications Engineer Application focus on LED lighting and motor control Support Renesas lines, V850, K0R, K0 20+ years embedded system development, application and industrial experience 12 yrs with Renesas Electronics/ NEC Electronics Hardware, firmware, development tools, applications 8 yrs with Electronics Detection Systems Life safety, security systems and CCTV 5 yrs with Anina (Romania) Power Generation Plant Power generator, plant automation, power inverters Knowledge in 8/16/32-bit MCUs (Renesas Freescale, Intel) MSEE San Francisco State University Diploma Engineer in Industrial Electronics from Polytechnic Institute Iasi - Romania 2 2

3 Renesas Technology and Solution Portfolio Microcontrollers & Microprocessors #1 Market share worldwide * ASIC, ASSP & Memory Advanced and proven technologies Solutions for Innovation Analog and Power Devices #1 Market share in low-voltage MOSFET** * MCU: 31% revenue basis from Gartner "Semiconductor Applications Worldwide Annual Market Share: Database" 25 March 2010 ** Power MOSFET: 17.1% on unit basis from Marketing Eye 2009 (17.1% on unit basis). 3 In the session 110C, Renesas Next Generation Microcontroller and Microprocessor Technology Roadmap, Ritesh Tyagi introduces this high level image of where the Renesas Products fit. The big picture. < 3

4 Renesas Technology and Solution Portfolio Microcontrollers & Microprocessors #1 Market share worldwide * ASIC, ASSP & Memory Advanced and proven technologies Solutions for Innovation Analog and Power Devices #1 Market share in low-voltage MOSFET** * MCU: 31% revenue basis from Gartner "Semiconductor Applications Worldwide Annual Market Share: Database" 25 March 2010 ** Power MOSFET: 17.1% on unit basis from Marketing Eye 2009 (17.1% on unit basis). 4 This is where our session, A17C Powering Driving and Dimming High Brightness LEDs with Renesas Lighting Microcontrollers, is focused within the Big picture of Renesas Products 4

5 Microcontroller and Microprocessor Line-up Superscalar, MMU, Multimedia Up to 1200 DMIPS, 45, 65 & 90nm process Video and audio processing on Linux Server, Industrial & Automotive High Performance CPU, Low Power Up to 500 DMIPS, 150 & 90nm process 600uA/MHz, 1.5 ua standby Medical, Automotive & Industrial High Performance CPU, FPU, DSC Up to 165 DMIPS, 90nm process 500uA/MHz, 2.5 ua standby Ethernet, CAN, USB, Motor Control, TFT Display Legacy Cores Next-generation migration to RX General Purpose Up to 10 DMIPS, 130nm process 350 ua/mhz, 1uA standby Capacitive touch Ultra Low Power Up to 25 DMIPS, 150nm process 190 ua/mhz, 0.3uA standby Application-specific integration Embedded Security Up to 25 DMIPS, 180, 90nm process 1mA/MHz, 100uA standby Crypto engine, Hardware security 5 Here are the MCU and MPU Product Lines, I am not going to cover any specific information on these families, but rather I want to show you where this session is focused 5

6 Microcontroller and Microprocessor Line-up Superscalar, MMU, Multimedia 78K Up to 1200 DMIPS, 45, 65 & 90nm process Video and audio processing on Linux Server, Industrial & Automotive High Performance CPU, Low LED Power Lighting Solution High Performance CPU, FPU, DSC Up to 500 DMIPS, 150 & 90nm process 600uA/MHz, 1.5 ua standby Medical, Automotive & Industrial Up to 165 DMIPS, 90nm process 500uA/MHz, 2.5 ua standby Ethernet, CAN, USB, Motor Control, TFT Display Legacy Cores Next-generation migration to RX General Purpose Up to 10 DMIPS, 130nm process 350 ua/mhz, 1uA standby Capacitive touch Ultra Low Power Up to 25 DMIPS, 150nm process 190 ua/mhz, 0.3uA standby Application-specific integration Embedded Security Up to 25 DMIPS, 180, 90nm process 1mA/MHz, 100uA standby Crypto engine, Hardware security 6 6

7 Agenda LED Lighting Market Design Considerations for LED Lighting Electronic Driver Solutions for LED Lights Design Electronics LED Driver with Renesas Lighting Microcontrollers 7 In the following 50 minutes or so we will talk about the lighting market in general What is it driving it a what part of the market stands out more than others. LEDs will certainly be our major focus. We will look at design considerations when building LED drive solutions Will talk about the electronic driver and finally we will talk about designing with Renesas 78K0 lighting microcontrolloers. 7

8 Key Takeaways By the end of this session you will be able to: Understand basic design considerations for LED lighting Understand the electronics of LED drivers Know what Renesas MCUs can offer for LED lighting designs 8 Key takeaways from this session will be: Basic design considerations for LED lights Understanding the electronics of LED drives Understanding what Renesas has to offer in terms of MCU for LED lighting designs. 8

9 Innovation Drive LEDs Powerline Communication Wireless (ZigBee) Time Sequencing Light Sensor DMX512 Console Motion Detector DALI Controller TRIAC Dimmer AC-Powered 9 What is the innovation in the LED lighting market? A microcontroller that can drive LEDs but not only that. It brings intelligence to lighting applications. It can dim the LEDs from a wall triac It can communicate through power line, wireless, DMX12, DALI. It can intelligently sense room occupancy, sense night and day. It can run the lights on a time sequence 9

10 Our LED Lighting Solution Renesas offers a complete set of tools and low cost MCUs with: Integrated peripherals for LED driver support Power processing capability Dimming control Intelligent lighting control LED lighting design is easily achievable when you have Renesas as a partner! 10 Our LED lighting solution <click> It provides a complete set of tools to enable you to develop an intelligent and cost effective LED lighting controller. <click> with integrated peripherals to support <click> power processing <click> dimming <click> intelligent control <click> LED lighting is easily to design when you have Renesas a s partner 10

11 LED Lighting Market 11 11

12 Lighting Market Overview LED lighting highest growth: 55% (by 2012); 235% (by 2015) *Datapoint Research 2008 (by Munits) LED 235% Incandescent -88% HID 39% CFL 7.4% Halogen -70% Fluorescent -10% General illumination white LED light highest growth *Databeans Estimates 2009 Now is time to focus on LED lighting design! 12 Lets see why is the lighting market so exciting? <<Click>> Datapoint Research estimates that among all alternative lighting solutions the LED market will grow by about 55% by 2012 and 235% by <<Click>> Among all alternative lighting solutions, LED will grow the most, way more than HID or CFL. Incandescent and halogen will loose substantial market share. --Pause-- There are two major areas of LED lighting: color LED lighting (RGB) and high-brightness white LED lighting. <<Click>> Both will experience substantial growth with the HB white LED lighting in the lead. <<Click>> So clearly, it is time to focus on LED lighting designs. 12

13 Reason for LED Lighting Growth in General Illumination Incandescent Fluorescent LED Light Energy efficiency 14.2 lumens/ watt 60 lumens/ watt 100 lumens/ watt Hours of Operation 1,000 10,000 50,000 Environmental Impact Consume too much energy Toxic: Contain Mercury (4mg for CFL) Environmentally Friendly Highest energy efficiency Longest operating life Non-toxic: No mercury Environmentally friendly! US Congress ban incandescent (12/2007) Program for solid state (LED) lighting 9/2008 L Prize competition sponsored by US DOE Fluorescent lamps hazardous waste in CA CA Title 24: 2008 Building Energy Efficiency Standards Many States LED light programs 13 What is driving the LED friendly market? <<Click>> If we compare three of the predominant lighting technologies used today we can see that: Incandescent light bulbs put out the least light per watt of electricity consumed and don t last too long. Fluorescents are much more efficient, last 10 times longer but contain toxic elements such as mercury. If we look at LEDs: <<Click>> they have the highest light output <<Click>> longest lasting <<Click>> and have the least harmful effect on the environment. <<Click>> These criteria make the LEDs Environmentally friendly! --Pause Saving the environment by building more energy efficient solutions and cutting back on toxic waste is now top priority for many governments around the world. <<Click>> The US government encourages environmentally friendly solutions through a number of laws and incentive programs Banning incandescent light bulbs by 2014, regulating the disposal of fluorescent bulbs, setting energy efficient standards. 13

14 General Illumination LED Lighting Market Primary Focus - White Source Light - Indoor Illumination (LED Light) - Commercial Displays - Street Lights - Outdoor Illumination 14 As previously seen the white LED market will increase the most which makes it: <<Click>> a primary focus in the area of the general illumination Application areas where we will see the benefits of LED lighting are: <<Click>> indoor such as residential commercial, retail and industrial <<Click>> commercial Displays found in many supermarkets, museums, vending machines <<Click>> street Lighting is a huge market <<Click>> outdoor lighting can be parking lots, architectural. Pools, etc. 14

15 General Illumination LED Lighting Market Secondary Focus - Multi-Color Lights Entertainment Light Architectural Indoor and Outdoor Light Traffic Signals Radiating Signs and Signals 15 The other area of LED lighting that it is going to grow <<Click>> is the color or RGB market. Although it will grow less than white LED market, it will still double by The major areas of color LED lighting are: <<Click>> Entertainment <<Click>> Architectural indoor and outdoor <<Click>> Traffic lights and emergency vehicle <<Click>> Radiating signs and Add panels <<Pause>> So clearly LED lighting is becoming a very exciting technology field with a very bright future. 15

16 Design Considerations for LED Lighting 16 And now let s look what it take to design with LEDs. 16

17 LED Light Dissection Reflector, Optics LEDs (Optical) Thermal Casing Cooling Fan (Thermal) Electronics Driver -LED driver -AC to DC conversion (Power factor correction) Renesas 17 Base Types (Mechanical) Edison Screw (E26 in USA), Prong, PL-T Power (85V 277V AC) 110V (Taiwan) 120V (USA, Canada) 220V (Most of Europe) 240V (UK) 250V (China) Lets look at the LED light and what is made off. LED lights come in many different shapes depending on the application but one of the most popular ones is a light bulb lookalike targeted towards replacing the existing incandescent light bulb. But it is a fairly complicated light bulb. <<Click>> First of course there are the LEDs. These are not signaling type we are most used to but high brightness high current ones (150mA 1.5A typical). Multiple are LEDs connected in series and parallel to form arrays of LEDs called light engines. An optical diffuser is needed to ensure light uniformity and color filtering. <<Click>> High-brightness LEDs become very hot and need a thermal casing to dissipate the heat. It may even contain a small fan for that. <<Click>> It has the typical Edison screw terminal, to fit in a traditional light bulb socket. <<Click>> It has to be able to work with different AC voltages. <<Click>> Finally one of the most important parts is the electronic driver that Renesas is the most interested in. The driver converts the high voltage AC to low voltage DC to drive the LEDs. 17

18 LED Light Electronics Driver Design Considerations Drive LED: Constant Current Drive Power Processing: AC to DC Conversion Power Factor Correction Dimming Control Communications for Lighting Control Intelligent Lighting Control LED Lighting Standards and Regulations 18 In the following few slides we will talk about design considerations for the electronic LED driver. As we will see this is a fairly complex circuit that need to address: <<Click>> Constant current regulation for the LEDs <<Click>> Power conversion with Power Factor Correction <<Click>> Dimming control <<Click>> Communication to facilitate <<Click>> Intelligent control of lights such as remote dimming, time schedule, occupancy detection etc. <<Click>> Finally we will look what is required from LED drives in terms of efficiency, power factor, EMI etc. 18

19 LED Drives: Constant Current Drive LED light is proportional to forward current Current fluctuation results in changes in LED light output, beam pattern and color Tight forward voltage specs are difficult to guarantee If Vdd R Vdd - Vf Vf Constant current regulation best approach Vin Constant Current Regulator Vout Vsense Rsense If 19 <<Click>> Light output of an LED is proportional to the forward current. <<Click>> If LED forward voltage is constant and we can provide a constant voltage Vdd the resulting current is constant. Tight forward voltage specs are difficult to guarantee and temperature will further affect the forward voltage. As a result constant current cannot be achieved with constant voltage drive. <<Click>> The answer to these problems is a constant current regulator that uses a current sensing resistor in a feedback loop. By monitoring the voltage on the sensing resistor we can compensate for forward voltage changes and adjusting the output voltage accordingly. 19

20 LED Drives: Constant Current Regulators Buck or Boost Buck: If input voltage higher than sum of LED forward voltages Boost: If input voltage lower than sum of LED forward voltages 20 Constant current regulators are switching regulators also known as DC/DC converters and can be <<Click>> Buck type, boost type or buck boost. <<Click>> Buck converter are called when the voltage on the output is lower than the voltage on the input. <<Click>> Boost converter are called when the voltage on the output is higher than the voltage on the input Boost converters are also used in the AC/DC power processing stage for power factor correction Both contain an inductor, a power switch, the load which are the LEDs. The output voltage is generated through PWM switching. The inductor acts as an energy storage tank and maintains an average current through the LEDs The size of the inductor is strictly related to the switching frequency and it gets smaller as the frequency increases. A current sensing resistor is used to maintain a constant LED current. 20

21 Power Processing: AC to DC Conversion LEDs powered by low voltage direct current (DC) AC mains provide high voltage alternating current AC to DC conversion Rectified DC output Power Factor Correction AC input Need to ensure efficiency and power quality 21 Power Processing is the AC to DC conversion <<Click>> To drive LEDs we need to use low voltage DC <<Click>> And we obtain this by converting high voltage AC power to low voltage DC <<Click>> And we need to do this efficiently and have a minor impact on the source. <<Click>> Because LEDs present nonlinear inductive loads to the source, we also need to have PFC. 21

22 Power Processing: Power Factor Correction What is Power Factor? Real Power (Watts) / Apparent Power (Volt-Ampere) Range: 0 1 PF = Non-linear loads displace and distort original AC current P( W ) S( VA ) AC voltage AC current Distortion φ Displacement Total Power Factor combination of Displacement Power Factor and Total Harmonic Distortion TPF = DPF 1 1+ THD 2 DPF: cosφ THD= 39 2 In 3 I 1 22 What is power factor? Why is it bad and how do we correct it? <<Click>> Power factor is known as the Real Power (in Watts) over Apparent Power in (Volt-Ampere). Apparent Power is the power supplied by the utility and Real Power is the power that does the active work. The power we transfer from a source to a load has two components: voltage and current. For typical resistive loads such as ordinary incandescent light bulbs the voltage and the current are sinusoidal and perfectly in-phase with each other. In this case the power factor is 1 and there is a perfect balance between the source and load. All off the power supplied is used as active power. <<Click>> With non-linear or inductive loads the current will be lagging behind the voltage and the shape will be heavily distorted. From the utility point of view not all the power supplied is used for meaningful work, some of it is lost. Due to the current peaks the wiring will have to be oversized to reduce the conduction losses though overheating. Ultimately these extra costs will be passed on to the consumers. The harmonic distortions can propagate back into the utility lines and affect other consumers. Power factor correction is a way to minimize all these negative effects non-liner loads have on the utility lines by bringing the power factor close to 1. <<Click>> So power factor is a combination of displacement power factor and total harmonic distortion. Where the displacement power factor is the angle between voltage and current and the total harmonic distortion is a sum of a number of harmonics over the fundamental 22

23 Power Factor Correction Make the load look like a resistor All power supplied is active power Passive PFC Control harmonic current using filter Expensive large high-current inductor No automatic adjustment for wider AC input power Higher efficiency than active PFC VDCIn + - L VDCout + Load - Active PFC Input current is controlled to be proportional to mains voltage waveform Automatic adjustment for wider AC input power (eg VAC) Most common configuration - Boost L D VDCIn VDCOut Other configurations Buck, Buck-Boost PWM T C Load 23 How is PFC implemented and what is the main goal? <<Click>> Make the load look like a resistor <<Click>> There are two major categories of PFC circuits used today: passive PFC and active PFC. <<Click>> Passive PFC uses passive circuits such as inductors and capacitors to filter the harmonic content and try to reduce the current peaks. The inductors and the capacitors tend to be large and bulky which limits the application areas. Passive PFC circuits don t do much about the voltage-current displacement and they achieve around 0.7 to 0.8 power PF. <<Click>> Active PFC circuits use active switching devices like MOSFETs or IGBTs driven by a PWM signal and their PF is close to unity. They can automatically adjust to the input voltage variations and can be used Boost, Buck and Buck- Boost topologies. If we compare the two from the efficiency point of view, passive PFC is more efficient because it doesn t have the switching losses active PFC has. With all the other advantages such as higher PF, smaller size, larger input voltage range and precise control of the output voltage it is the more preferable method. 23

24 Dimming Control Adjust forward current of LED Digital PWM Dimming Change LED constant current with PWM pulse If Constant Current Regulator Vout If If PWM Internal Ref Rsense Analog Dimming Change LED current by current sense threshold t Vin Vout If If Vref Rsense t 24 To dim LEDs we need to be able to control the LED current. The light output of an LED is direct proportional to the forward current. To change the current we can use digital or analog current control. <<Click>> The first one is called Digital PWM Dimming We change the current using PWM method. A current sensing resistor is used for constant current regulation. <<Click>> The second is the Analog Dimming method and it uses a linear current regulation through a linear current source and a reference voltage. 24

25 Types of Dimming Control 0 10V Dimmer Applications: Indoor/ Outdoor lighting with one or more zones 0-10V + - Control + - N L 0-10V Dimmer + - N L 0-10V Dimmer Ground Neutral Mains Line 25 Besides how the actual current through the LEDs is controlled there are also different front-end dimming technologies. <<Click>> One is the 0 10V DC analog where one common DC signal sets the dimming level for multiple dimmer units. 25

26 Types of Dimming Control DALI Digital Light Addressable Interface Open standard (IEC 60919) Addressable up to 64 devices, Data transfer up to 1200 Baud Application: Indoor/Outdoor Lighting DALI + - Control + - N L DALI Dimmer + - N L DALI Dimmer Ground Neutral Mains Line 26 <<Click>> Other widely used dimming method is through digital DALI protocol. <<Click>> Regulated by an open standard <<Click>> It can control up to 64 individual dimmers at up to 1200 Baud speeds. <<Click>> Applications: Indoor/Outdoor lighting 26

27 Type of Dimming Control DMX512 Bus network: < 1200 meters; < 32 devices EIA-485 physical layer; Twisted pair wiring Connector: XLR (5-pin) or RJ-45 (8-pin) OUT IN OUT IN OUT Termination 120ohm Advanced Dimming Control Wireless: ZigBee or Proprietary wireless Power line communication 27 Another type of dimming is <<Click>> through DMX 512 protocol. <<Click>> DMX 512 is an industry standard used for stage lighting that runs over an EIA-485 twisted pair serial bus up to 1200 meters long. It can control individual lights up to 32 addresses. DMX 512 can control not only the light intensity but can remotely control the position of the lights. Other ways of controlling LED light dimming is through various wireless technologies such as: <<Click>> ZigBee <<Click>> Or through power line communication networks. 27

28 Types of Dimming Control TRIAC Dimmers Change TRIAC conduction angle to dim light Incandescent light bulbs are pure resistive loads No current distortion Unity Power Factor LED drives need intelligence Inductive load degrades power factor Light load, not enough to keep triac on causing flicker Switching noise can shut off triac - causing flicker Thermal management VR δ 120 VAC LED Drive R C Diac Triac δ 180 δ: conduction angle The most commonly known residential and commercial dimmers are: <<Click>> Triac dimmers. These dimmers use a triac as a main component. A triac can be turned on at any angle on both positive and negative AC cycles and stay on until the voltage drops to 0. By controlling the conduction angle we can effectively control the AC voltage amplitude on the source which is the light bulb in this case. A capacitor charges up through a variable resistor. The voltage on the capacitor is seen by a Diac that is similar in behavior with a zener diode. When voltage exceeds a certain threshold the Diac fires into conduction and turns on the Triac. Once the Triac is on it will stay on for the rest of the half cycle. When the AC voltage naturally decreases to 0, the Triac turns off and stays off until is fired again by the Diac on the next AC cycle. <<Click>>Triacs work well with incandescent light bulbs because they are pure resistive loads, no phase shift, no current distortion, unity power factor. <<Click>> LEDs need intelligence <<Click>> Inductive loads degrade power factor <<Click>> In order to stay on during the conduction period, Triacs need to have a minimum current flowing to the load which is in the order of 30mA to 50mA. Incandescent light bulbs do not have a problem keeping the Triac on and even if they do we will not be able to see any flicker. LEDs lights on the other hand are very light loads and when we start dimming down at some point the Triac will not have enough current to stay on. The result will be visible flicker. <<Click>> Switching noise can feed back into the triac and may cause the shut off causing flicker. This is one of the greatest challenges LED drive designers face today. Everyone is struggling with this. <<Click>> Finally there is thermal management to take in consideration. 28

29 Communications for Lighting Control Microcontrollers enable multiple lighting control options from local or through network communications 0-10V ADC LED Driver DALI DALI Microcontroller UART SPI DMX512 ZigBee Module Powerline Communication Module 29 One of the great innovations in LED lighting is communication. <<Click>> Especially microcontrollers are well suited for that because of the various peripherals they have. <<Click>> For 0-10V analog we can use the ADC, for DMX512 and DALI we can use the UART, to communicate with ZigBee or PLC we can use the SPI For the LED driver we can use PWM timers. 29

30 Intelligent Lighting Control Microcontroller enable intelligent lighting control Motion detection Ambient light sensor Time sequencing Energy savings Light sensor LED Driver Timer for time sequencing PIR sensor ADC Microcontroller SPI Occupancy sensor 30 Microcontrollers enable intelligence lighting control <<Click>> Motion detection for occupancy <<Click>> Ambient sensing for day and night <<Click>> Time sequencing <<Click>> which lead to energy savings 30

31 LED Lighting Standards and Regulations U.S. Energy Star Power processing: Power factor: Residential > 0.70; Commercial > 0.90 EMI, noise, light output and efficiency National Electrical Manufacturers Association (NEMA) Recommended performance requirements and test For SSL Driver: NEMA SSL-1 Underwriter Laboratories (UL) Independent nonprofit product safety certification organization UL8750: Standard for Lighting Emitting Diode (LED) Light Sources for Use in Lighting Products American National Standard Institute (ANSI) Official US representative to International Organization for Standardization (ISO) For SSL Drivers: Working group ANSI C82-04 Illuminating Engineering Society of North America (IESNA) Professional organization to improve the lighted environment 31 Besides the great capabilities of microcontrollers in the lighting applications, we need to be aware of the various standards and regulations to understand how we can meet them. 1. First of all we have the US Energy Star program which mandates that PF for residential lighting has to be better than 0.7 and better than 0.9 for commercial. Energy Star also mandates EMI, light output and efficiency. 2. NEMA SSL-1: Title: Electric drivers for LED devices, arrays or systems Scope: To provide specifications for and operating characteristics of electronic drivers (power supplies) for LED devices, arrays or systems intended for general lighting applications. Electronic drivers are devices that use semiconductors to control and supply DC power for LED starting and operation. 3. UL to provide safety requirements not only for the electronic drive but also for the LEDs as light sources. 4. Other organizations are the ANSI which is US representative of ISO and IESNA a professional organization to improve lighting conditions. 31

32 Electronic Driver Solutions for LED Lights 32 Lets look at the electronic driver for LED lighting 32

33 LED Lighting Electronics Driver Solutions LED Driver Analog LED Driver PFC Dimming Control MCU Intelligent Lighting Control Lighting Control Comm. Light sensor PIR sensor Occupancy Sensor for time sequencing Intelligent Lighting Control LED Driver Renesas MCU PFC Dimming Control Lighting Control Comm. 0-10V DALI DMX512 ZigBee Powerline Communication 33 <<Click>> Analog solutions contain the LED driver and may or may not contain the power factor correctrion. But for intelligent lighting control they will certainly need a microcontroller. Well if you need a microcontroller anyway, why not combine these features in a single intelligent unit. Are there such a devices? <<Click>> Yes there are and these are the Renesas lighting MCUs. LED driver, dimming control, communication and sensing in one. 33

34 Design Electronics LED Driver with Renesas Lighting Microcontroller 34 In this next section we will talk about the Renesas lighting microcontrollers. 34

35 Renesas LED Lighting Microcontroller Line-Up High-Current LED Key Features Driver MCU (HCD/LED) Line-up UPD78F KB Flash UPD78F KB Flash UPD168804/30 LED Driver only Integrated 4-channels constant current LED driver Current drive: 0.35A to 1.5A Buck or boost topology 1 MHz switching frequency 9 38VDC input voltage Protection circuit (over-current, over/under-voltage, thermal) Flash memory for communication protocol (PLC, Wireless) Multiple channels of LEDs for multi-color and simultaneous LED channels 78K0/Ix2 MCU Line-up 78K0/IB2 8KB-16KB, 30-/32-pin 78K0/IA2 8KB-16KB, 20-pin 78K0/IY2 4KB-16KB, 16-pin Key Features Fast (40MHz) 16-bit inverter control timers Analog comparators (3-ch) w/ int. Vref (1.6V divided by 32) Analog digital converters (9-ch 10-bit ADC) Op-amp (1-ch) Hardware DALI interface Operating temperature: -40C to 105C Combination of 40 MHz 16-bit PWM + Analog comparator: Power factor correction (0.99) Constant high-current drive 8-bit timer for dimming control 35 <<Click>> The first family is the High current LED driver MCUs. <<Click>> There are two devices with four channels of integrated drivers that can handle 0.35A to 1.5A each. Configurable in boost or buck topology with up to 1 MHz switching frequency, 9 to 38V output, overvoltage, over-current detection with internal comparators <<Click>> Flash memory based, well suited for multicolor LED lighting The third product in the family is a standalone LED driver only. <<Click>> The second family is the single channel 78K0/Ix2 with three device to chose from. <<Click>> This MCU has 16-bit timers that run at 40 MHz It has three internal comparators, one internal OP Amp and one programmable gain amplifier. It also has a hardware Dali interface. This product is targeting constant current white LED lighting with power factor correction 35

36 Renesas LED Lighting MCU Easy to Design Development tools, reference designs High Temperature Support 78K0/Ix2: -40 to 105C Power Factor Correction Renesas Lighting MCU Constant Current Drive HCD/LED MCU have integrated 4-channels LED driver 78K0/Ix2 have fast PWM timers and analog comparators to implement Dimming Control 8-bit or 16-bit resolution 0-10V, DALI, DMX512, TRIAC, ZigBee, Powerline Protection Circuit HCD/LED MCU have overcurrent, over-voltage, undervoltage and thermal detection circuits Intelligent Lighting Control Interface to sensor (using 10- bit ADC) Sequencing on-off based on time (using timers) Network Lighting Control DALI interface DMX512 (using UART) 0-10V (using 10-bit ADC) ZigBee (add ZigBee module through SPI or UART) Powerline (add powerline controller or module through SPI or UART) 36 So lets look at what are the key benefits in using Renesas Lighting MCUs: <<Click>> Power factor correction <<Click>> Constant current drive <<Click>> Dimming control <<Click>> Networking for lighting control <<Click>> Intelligent lighting control <<Click>> Protection <<Click>> High temperature support <<Click>> Easy development support 36

37 Renesas 78K0 LED Lighting MCU: Applications White LED Light/ Light Bulb Multi-Color Light White Outdoor Illumination 78K0/Ix2 HCD/LED MCU White Light Commercial Displays LED Street Light 37 Major application areas for the Renesas MCUs are: <<Click>> For IX2 <<Click>> Indoor white LED lighting <<Click>> Outdoor white LED lighting <<Click>> White LED commercial lighting. <<Click>> For the High current LED drive MCUs <<Click>> Multi color lighting and street lighting 37

38 Implementation of Dimmable LED Driver with Renesas 78K0/Ix2 Microcontroller 38 Now lets look at a practical design of a Triac dimmable LED drive with the Renesas 78K0/IxB microcontroller <<Click>>Here is block diagram showing the different components The AC voltage from the triac output is rectified power factor corrected and boosted to 200VDC to 400VDC. The boosted voltage than is buck down to a low voltage to drive the LEDs. To dim the LEDs, a triac conduction angle detect circuit is employed right after the bridge rectifier. And all this is controlled by the 78K0/IB2 MCU. 38

39 Dimmable LED Driver with 78K0/Ix2 PFC Boost Converter DC BUS DC/DC Buck Converter Rectified AC Input L LED T1 T2 LED Current Sensing Zero current detection TMX00 ANI0 TMX10 TMX0 A/D TMX1 Triac angle decoder CMP2+ TI000 Internal Vref Interlock TM00 78K0/Ix2 Dimming TMH1 Interlock Internal Vref CMP0+ 39 Here is a more detailed block diagram showing the major components of the two DC/DC converters as well as the special peripherals the IB2 is using. So again, we have a PFC Boost converter and a Buck converter. <<Click>> For the converters we use two of the 16-Bit timers <<Click>> For current detection we use the built in hardware compatators <<Click>> For dimming we measure the triac conduction angle with another 16-bit timer and load the information in <<Click>> an 8-bit timer PWM output modulates the Buck converter output.. 39

40 Active CRM Power Factor Correction PFC Boost Converter DC BUS Rectified, unfiltered AC voltage Average AC current T1 Critical Conduction Mode (CRM) Zero current detection TMX00 ANI0 Triac angle decoder CMP2+ TI000 TMX0 Internal Vref A/D Interlock 78K0/Ix2 TM00 TMX00 (PFC output) TX0CR0 (PFC-on pulse width) CMP2+ (Zero current detection) TX0CR1 (PFC-off pulse width) 40 The PFC circuit seen in the slide is an active PFC and uses the critical conduction (CRM) method assisted by one of the internal hardware comparators. PFC is about controlling the AC current so that it is perfectly in phase with the AC voltage and it is of a sinusoidal shape. This is essentially achieved by turning on and off the current through an inductor at a variable rate or duty cycle using a power switch. When the switch is closed the current through the inductor increases in a linear fashion accumulating energy and charging up a bulk capacitor. When the switch is open the current continues to flow and charge the bulk capacitor due to this accumulated energy but it will decay. In the CRM method when the current reaches zero, the switch is closed again. Other methods are continuous conduction mode (CCM) and discontinuous conduction mode. Now lets see how we implemented the CRM method. <<Click>> The PFC inductor has a secondary which we monitor with the internal comparator. <<Click>> The comparator output controls the output of the 16-Bit timer driving the power switch. <<Click>> First we turn on the timer output for a period of time Ton. This allows the current through the inductor to rise to a value dictated by the input voltage and Ton. <<Click>> After Ton expires, the switch is turned off allowing the current to decay and it is shown as Toff. <<Click>> At this time the comparator output turns on the switch again and the cycle repeats. Ton is considered constant but it is adjusted by the controller to maintain a certain DC voltage on the output. Toff is variable and it is changing with the value of the voltage amplitude through the AC cycle. With this method we have a variable frequency signal driving the power switch. 40

41 Question 1 What PFC method is used in the Renesas Triac dimmable LED drive? A. Passive PFC B. Active PFC in Discontinuous Conduction Mode (DCM) C. Active PFC in Continuous Conduction Mode (CCM) D. Active PFC in Critical Conduction Mode (CRM) 41 And now we have a question: <<Click>> What PFC method is used in the Renesas Triac dimmable LED drive: A?, B?, C? or D? <<Click>> And the answer is D 41

42 Constant Current DC/DC Buck Converter DC BUS DC/DC Buck Converter L LED T2 LED Current Sensing Average LED current Inductor current Internal Vref TMX10 78K0/Ix2 TMX1 Current Sense Input (CMP0+) Internal CMP output Dimming Interlock CMP0+ PWM output (TMX10 Ton Toff TMH1 Internal Vref 42 Now lets look at the DC/DC buck converter part So, we have a DC bus voltage of 200 to 400V provided by the PFC boost circuit and we need to drive a string of LEDs at a considerably lower voltage. <<Click>> We implemented the buck converter with a second 16-Bit timer driving another power switch. The inductor and the LEDs are in series so the current through the inductor and LEDs is the same. By switching on and off this current we can maintain an average current through the LEDs. To maintain a constant current we use a second internal hardware comparator which is interlocked with the timer output. <<Click>> First we turn on the power switch for a Ton period. The current through the inductor and LEDs increases until the comparator threshold is reached when <<Click>> the switch is automatically turned off for a Toff period. After Toff expires, <<Click>> the switch is turned on again and the cycle repeats. <<Click>> In this case Toff is constant and Ton is variable based on the current sensing by the comparator. The internal comparator threshold can be set in 32 steps from 0.05V to 1.6V and it sets the constant current through the LEDs. <<Click>> Another timer that controls the switch is the dimming timer. This is used to modulate the timer output to set the dimming level. 42

43 Question 2 What method of current regulation is used in the buck converter? A. Constant current control by software B. Constant current control by internal hardware comparator C. Constant current control by external hardware. 43 And now we have another question: <<Click>> What method of current regulation is used in the buck converter? A?, B?, or C? <<Click>> And the answer is B 43

44 Dimmable LED Light Reference Design Replacement/ Retrofit to LED Light for Indoor, Outdoor and Display Dimmable LED Reference Design Electronics driver LED lights AC-DC Conversion AC Voltage Input VAC Power Factor Correction >0.95 Constant Current HB-LED Drive One-channel up to 20W TRIAC Dimming Programmability 78K0/Ix2 Flash-based MCU VAC 44 This is a reference design we developed for the triac dimmer. <<Click>> It is a 2 x2 PCB with the following features: <<Click>> Electronics to drive the LEDs <<Click>> AC-DC conversion <<Click>> 85 to 277VAC input <<Click>> greater than 0.95 PF <<Click>> Up to 20W of constant current LED drive <<Click>> Triac dimming support <<Click>> Programmability through the 78K0/IB2 flash based microcontroller 44

45 Dimmable LED Light Reference Design Output: 20-65VDC, 350mA LED- LED+ L N Input: VAC 45 A closer look at the board shows: <<Click>> the PFC inductor <<Click>> the bulk capacitor <<Click>> the buck inductor 45

46 Innovation Drive LEDs Powerline Communication Wireless (ZigBee) Time Sequencing Light Sensor DMX512 Console Motion Detector DALI Controller TRIAC Dimmer AC-Powered 46 In summary lets look again at the innovation microcontrollers can bring to the lighting market? It brings intelligence to lighting applications to be able to dim the LEDs from a wall triac or other dimming technologies, It can communicate through power line, wireless, DMX12, DALI. It can sense room occupancy, sense night and day. It can run the lights on a time sequence 46

47 Questions? 47 Any questions? 47

48 Thank You! 48 48

49 Renesas Electronics America Inc. 49