Freescale High-Brightness LED Solutions
The Future of Lighting Low Power, Lofty Opportunities
freescale.com/lighting The Future of Lighting
Freescale High-Brightness LED Solutions Market Overview
The New Light
High-brightness light emitting diodes (LEDs) are taking the lighting industry by storm. Brilliant colors, long life and energy efficiency are just three reasons why high-brightness LEDs are gaining rapid popularity in the automotive, consumer and industrial markets. With improved output intensities, drive circuitry and packaging technologies, high-brightness LED systems offer tremendous opportunities for dazzling new lighting applications.
High-brightness LEDs are used in outdoor signage, innovative building designs, landscaping, traffic signaling, medical diagnostics instruments, aircraft interiors and as alternatives in flashlights, bicycle lights, lanterns and entertainment lighting.
Benefits: • Energy efficient • Long operating life (up to 100K hours of operation) • Fully dimmable saturated colors • Automatic on • Environmentally friendly products • Durability • Range of true colors • Compact size • Programmability • Design flexibility
High-power LED systems require a constant current to maintain color integrity and provide luminosity. For portable devices the system also needs to be smart enough to alert the user to a low-battery condition and compensate to maintain the constant current through the LED.
Freescale Semiconductor's intelligent high-brightness LED driver solutions can be set to act as a constant current control to configure the LEDs operated in a rated forward current. They also have power saving features to limit the loss on LED driving stages and over temperature/ voltage/current fault detection to help protect the system. With Freescale’s simple interface, microcontrollers (MCUs) help control the parameters to generate correct colors for a particular application.
In the following pages you will find information about Freescale’s controlled solutions for architectural lighting, LCD backlight applications and MR16 LED bulb applications (intelligent flash lights) among other applications that can greatly benefit from LED technology. On our Web site, www.freescale.com/lighting, you’ll find the technical documentation you need on Freescale’s MCU portfolio and development tools and reference designs to help you get started on your new high brightness LED project development.
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Freescale High-Brightness LED Solutions Control Interface Application Note
The control of high-brightness LEDs (HBLED) requires a constant current, maintained over temperature and voltage. Care must be taken to design a driver and control system that will optimize reliability and accuracy by delivering constant current. Using a cost effective MCU to power the HBLED increases system flexibility and functionality for the next generation of lighting applications. LED luminosity and reliability depend on the thermal control an MCU can provide. In addition, control protocols such as DALI, DMX512 and the ZigBee™ specification can be implemented at a low cost using MCU-based LED drivers.
Freescale’s application note High Power LED Driver Interface (AN3321) introduces the user to MCU-based LED drivers using DC-DC converters with buck, boost or buck/boost topologies. The contents of the application note include: • Overview of power terminology, LED specifics and MCU interface and control options • High-brightness and high-current LED control, covering buck, boost and buck/boost topologies • MCU control of DC-DC converter • An MCU base driver example with design goals, control loop description and component selection • Lighting control protocols DALI, DMX512 and the ZigBee specification • User interfaces, including LCD display, button and slider switch • Cross references and an appendix with DALI and DMX command stacks
The full application note is available as a PDF download from www.freescale.com/lighting.
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Freescale High-Brightness LED Solutions Architectural Lighting Application
Innovative new high- Overview the MCU to remotely control additional light sources through brightness LED-based Architectural lighting is an application market such communication protocols as DALI, technology can use light where aesthetic design is as important as DMX512, Ethernet, USB, RS232 and the to transform spaces, sites illumination. It covers outdoor illumination for ZigBee specification. buildings, towers, bridges, squares, signage and building signs into and others as well as indoor illumination for The MCU-based system must be cost striking works of art. rooms, lobbies and halls. Innovative new effective and flexible enough to support HBLED-based technology can use light to multiple LED-based lighting sources of HCS08 Microcontroller Family transform spaces, sites and building brands different types powered by 12V DC–24V DC into striking works of art. It can even be used power supply units. The system also requires Required Features to replace neon signs and bulb lamps. enough memory to store different scenes and • 16K in-application re-programmable to support a stand-alone playback mode. flash memory Design Challenge Different techniques are used for dimming • 1K random access memory (RAM) The MCU-based control solution for HBLED control, including pulse-width modulation, • 8-channel, 10-bit analog-to-digital architectural lighting is a lighting playback frequency modulation and bit-angle converter (ADC) controller or interpreter, which stores or modulation. Each technique requires a • SPI, I²C, 2x SCI translates a specific scene or sequence for different level of MCU performance, therefore • Dual 2-channel, 16-bit timers (IC, future playback. It sets the desired dimming any MCU-based system should be powerful OC, PWM) level and turns specific light sources on or off enough and flexible enough to support any of • Internal clock generator (zero external to produce the required illumination scene. these dimming techniques. components) Furthermore, integrated connectivity enables • Programmable frequency-locked loop (FLL) and post-FLL divider generates from 32 kHz to 20 MHz bus speeds Architectural Lighting • Trimmable with temperature and voltage compensation (typically < 2% drift) 12V DC–24V DC • Optional external crystal, resonator AC Input or clock 12V DC–24VDC • System protection MCU power supply • Computer operating properly (COP) 3.3V DC or 5V DC • Low-voltage detect/reset @ nominal 1.8V • Low-battery warning at nominal 2.4V or 2.1V PWM PWM Control ADC/ PWM Comp Rs Control
ADC/ Comp S08 MCU Iout
SPI UART GPIO & Timer FB Control Rs Rs
ZigBee™ DMX DALI
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Freescale High-Brightness LED Solutions DMX512-SMAC Bridge
The 908E625 is a highly integrated HBLED solutions. It also demonstrates the single-package 8-bit solution that includes a Freescale-integrated solution using general high-performance HC08 microcontroller with purpose microcontrollers, analog devices and a SMARTMOS™ analog control IC. The HC08 intelligent distributed control ICs. However, in includes flash memory, a timer, enhanced many applications driving the HBLED is not serial communications interface (ESCI), an the only requirement. The DMX512-SMAC ADC, serial peripheral interface (SPI) and an bridge board gives users the capability to internal clock generator module. The analog incorporate wired or wireless connectivity in control die provides fully protected H-Bridge/ their HBLED solutions. high-side outputs, voltage regulator, watchdog and local interconnect network HBLED 908E625 Board (LIN) physical layer. • Features the 908E625 MCU • I/O emulating SPI communication to The single-package solution, together with MC13192 RF transceiver LIN, provides optimal application performance • SMAC 4.1 to control the MC13192 adjustments and space-saving PCB design. It • Buck regulator implementation to is especially suited for automotive mirror, door drive HBLEDs lock and light-leveling applications control. • Capable of driving 4-350 mA HBLEDs • Internal low-side MOSFETS using current MM908E625 Features limitation feature • High-performance M68HC08 core • 100 Hz PWM with 20 steps for LED • 1616K on-chip flash memory dimming • 512 Bytes RAM • Code Size: 4381 Bytes • Two 16-bit, 2-channel timers • RAM Size: 132 Bytes • 10-bit ADC • Three 2-terminal hall sensor inputs DMX512—SMAC Bridge Board • One analog input with switchable • Features the 9S08GT60 MCU current source • Supports DMX 512 serial protocol • Four low-resistive half-bridge outputs • RS485 standard @ 250 Kbps • One low-resistive high-side output • Uses SMAC 4.1 to control the MC13192 • 16 microcontroller I/Os RF transceiver • Currently supports four channels Application Features • Code Size: 4018 Bytes An evaluation tool using a Freescale • RAM Size: 1448 Bytes HBLED 908E625 board with a DMX512- SMAC bridge board is a general-purpose platform that allows users to prototype their
RS485 RF
DMX512 Bridge Board HBLEDs RD Board
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Freescale High-Brightness LED Solutions Promotorch
Overview 10-bit ADC for accurate measurements and supply, which maximizes energy transfer an internal band-gap reference to monitor between the battery and the HBLED. HBLEDs, offering dramatic improvements battery voltage for brightness compensation The 908QB microcontroller measures the in solid-state lighting over traditional LEDs, and system battery level. current through its 10-bit ADC then uses are rapidly spreading into a number of that feedback to control light output on new applications in automotive, consumer Promotorch the HBLED. A potentiometer controls the and other important markets. When using brightness. Eight traditional LEDs provide Freescale demonstrates its ability to control this new technology, however, new design visual feedback on the battery voltage status HBLEDs with Promotorch, a demo platform challenges need to be addressed. HBLED and the HBLED intensity levels. systems require a high constant-current to based on a buck topology switching power deliver superior light output and maintain color integrity. Systems need to be smart enough to know when the source voltage is dropping and to compensate to maintain constant current through the LED.
Freescale's general-purpose 8-bit MCUs are excellent system-level controllers, offering a high level of on-chip integration, including a
Promotorch Demo Board
SW1 L1 Q1 1 2 3 220UH IRF75241
C1 Q1 1 R11 BAT1 D1
2
1 BAT2 LUXEON 2 C2 C3 VDD R12 R16 LED8 LED6 LED1 LED2 LED5 LED4 LED3 LED7 VDD A A Y A Y A A Y MC68HC908 PTA0/TCH0/AD0/KBI0 1 R14 PTA1/TCH1/AD1/KBI1 16 13 PTA2/IRQ/KBI2/TCLK 12 CW PTA3/RST/KBI3 9 RP1 PTA4/OSC2/AD2/KBI4 C4 R6 R5 R7 R2 R8 R4 R3 R1 PTA5/OSC1/AD3/KBI5 R15
3 AD4/SCK/PTB0 SW2 2 AD5/MOS/PTB1 15 AD6/MSO/PTB2 14 AD7/SS/PTB3 11 AD8/RX/PTB4 10 AD9/TX/PTB5 7 TCH2/PTB6 6 TCH3/PTB7 VSS
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Freescale High-Brightness LED Solutions MC9RS08KA2 Controlled High-Brightness LED
Overview KA2 8-bit MCU offers an economical This maximizes energy transfer between solution for this application. The on-chip the battery and the HBLED. The KA2 Innovative HBLED solutions are rapidly analog comparator is designed to provide an microcontroller is used to measure the current gaining popularity in low-cost applications accurate current measurement, which allows through its on-chip analog comparator, then that require an extremely cost-effective feedback control to maintain a constant level uses that feedback to control luminosity bill-of-materials. However, low-end HBLED in the LED forward current. intensity on the LED. The user can toggle applications still require a high level of system between two MCU-controlled potential divider control as well as high constant-current to KA2 HBLED Demo settings to vary the LED brightness levels. The maintain color integrity and high light output. demo unit also includes an open-source BDM Freescale demonstrates its ability to control Freescale’s general-purpose ultra-low-end interface for easy firmware evaluation. the HBLED with a KA2 demo unit based on Options for Advanced Functionality a buck topology switching power supply. Recommended Device Key Features 8-bit PWM, 10-bit ADC, SCI, MC9S08AW60 SPI, I2C, Flash, ICS 16-bit PWM, 10-bit ADC, SCI, MC9S12GC26 SPI, Flash, Low-Pin Count DSC PWM, 10-bit ADC, SCI, 56F801 SPI, Flash, Low-Pin Count
MC9RS08KA2 EVB+HBLED Demo
MCU_VDD BDC_RESET_VPP BDC_BKGD
JP3 R27 C21 C22 MCU_VDD 1 2 U3 R28 BDC_RESET_VPP 1 8 ACMP+ 3 PA2/K2/RST PA0/K0/A+ 2 7 ACMP- PA3/AO/BKGD PA1/K1/A- MCU_VDD 3 6 PWM Q4 VDD PA4/K4 GND 4 5 DIM1 VSS PA5/K5 L3 GND D8 R30 9RS08KA2DN WARM-WHITE C20 SW2 D7 C23 C24 R29 C25
MCU_VDD GND
GND R24
ACMP+
R25 R26
DIM0 DIM1
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Freescale High-Brightness LED Solutions MR16 LED Bulb Application
Overview LED Bulb Demo
HBLEDs offer several advantages over The QT2 is used as an intelligent driver to halogen bulbs for high-power lighting control the LED brightness level. A buck solutions. These include longer operating life, topology switching converter is implemented low-volt operation and no mercury or fragile to convert a 12V input supply to a current glass. The major design challenges when regulated output for LED driving. Power replacing halogen bulbs with HBLEDs include: metal-oxide semiconductor field-effect how to implement a drop-in replacement for transistor (MOSFET) switching is controlled by a compact-sized halogen bulb in a standard the MCU’s PWM output, and the LED current MR16 form factor; how to convert a 12V is monitored by an ADC module through a supply to drive the LED with constant current current sensing circuit. Based on the feedback and how to control dimming settings without voltage from the ADC, the MCU is designed additional wiring. to adjust the PWM duty cycle in close-loop control to keep a constant LED driving Freescale’s general-purpose 8-bit current. The dimming level can be adjusted MC68HC908QT2 MCU offers a high level by directly changing the regulated LED of on-chip integration for this application, current, which is proportional to the target including an 8-bit ADC designed to provide value used in the ADC comparison loop. accurate measurements on LED forward The pre-set dimming levels (target values) current, a 16-bit timer module to generate a are stored in MCU flash memory. When the PWM control signal for DC-DC conversion system is powered on, the brightness setting and on-chip flash memory for storing the is established when the previous dimming dimming settings. level is restored from memory. The current dimming level is designed to be saved in memory again if the system is operated for more than 12 seconds, otherwise the next step dimming level will be recognized as the configuration for the next power-on-brightness setting. There is no additional control signal for dimming setting, only the power-on-time is used.
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Freescale High Brightness LED Solutions MCF532x
Options for Advanced Functionality QT2 LED Demo Board Recommended Device Key Features 8-bit Supply MBR0520LT1 (SOD-123) PWM, 10-bit ADC, SCI, 2 D3 MC9S08QG4 SPI, I C, Flash, ICS, VIN ACMP CON2 1 16-bit 2 R9 D6 D5 D4 PWM, 10-bit ADC, SCI, 2PINBASE C5 MC9S12GC26 SPI, Flash, Low Pin C6 VDD Count C3 C4 D7 DSC
PWM, 10-bit ADC, SCI, MM3Z5V1ST1 (SOD-323) 56F801 SPI, Flash, Low Pin Count
MCU DC-DC Converter
U1 VIN AUTO 1 PTA0/AD0 PTA1/TCH1 8 PWM 2 VSS PTA2/KB12 7 PTA2 R1 3 VDD PTA3/KB13 6 PTA3 VDD 4 PTA5/DSC1 PTA4/AD2 5 PTA4 PTA5 MC68HC908QT2 ISEN D1 CON3 L1 1 2 CON2 AUTO PWM 1 3 4 PTA2 C1 2
5 6 PTA3 MBR1301T1 (SOD-123) 2PINBASE VDD 7 8 PTA4 HEADER_2X4 D PTA5
R2 G PWM Q2 S R3
Current Sensing
VIN
R7
D2 E ISEN B Q1
C R8 R4 AUTO
R6 C2
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Freescale High-Brightness LED Solutions Backlight Solution
Freescale offers Overview Intelligent Driver exceptional support, Using an HBLED backlight system in an LCD The intelligent driver solution creates new helping customers to monitor or TV offers dramatic advantages opportunities for cost-effective HBLED design smarter products over conventional cold cathode fluorescent backlight designs. It includes constant-current lamp (CCFL) backlighting, delivering more control to configure the LEDs operated and get them to market brilliant colors and brighter pictures in a more in rated forward current, a power saving faster. environmentally friendly solution, since this is feature to limit the loss on LED driving stages a totally lead-free and mercury-free solution. and over-temperature/voltage/current fault Options for Advanced Functionality HBLED backlight system design requires a detection to help protect the system. A smart and adaptive control methodology to simple interface can easily set up the desired Recommended Device Key Features ensure optimized color space for different color space, and the MCU can control all 8-bit display contents, excellent color contrast for parameters to generate the correct colors for desktop publishing and a consistent color a particular application. The control algorithm PWM, 10 bits ADC, SCI, MC9S08QG4 SPI, I2C, Flash, ICS, setting in manufacturing. maintains accurate color tracking over the ACMP temperature range and is able to compensate 16-bit Freescale provides a comprehensive range of for characteristics drift on analog devices. PWM, 10 bits ADC, SCI, solutions with value extending far beyond a MC9S12GC26 SPI, Flash, Low Pin basic controller or analog control circuit. Count DSC PWM, 10 bits ADC, SCI, 56F801 SPI, Flash, Low Pin Count
Backlight LCD Display
LCD Panel and Intelligent Back Light Module Driver
Interface to LCD Intensity Color Controller for Adjusting Uniformity Sensor Panel Color Temp, Brightness Feedback Inputs Temperature
OSC SCI/SPI ADC Channel Freescale PWM INT MCU Sync GPIO Flash/RAM Core Timers Safety DBG Detection
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Freescale High-Brightness LED Solutions Implementing DMX512 Protocol
Entertainment lighting markets have adopted the DMX512 protocol because it’s simple and has the necessary characteristics for a single, unified-illumination standard.
The HBLED market is attracting new players as low-end MCUs enable new applications. These newly enabled applications include automotive signage, mobile appliances and a wide variety of general illumination systems. Some novel uses for HBLEDs range from water purification modules to automated systems for cultivating vegetables through the combined use of RGB LEDs.
In many cases, these new applications will be controlled by a central control unit that requires a connectivity interface. In the lighting market today this connectivity is dominated by two protocols: DMX512 and DALI. Freescale’s Application Note DMX512 Protocol Implementation Using MC9S08GT60 8-bit MCU (AN3315) details how the DMX512 protocol can be deployed using a popular Freescale 8-bit microcontroller. The contents of the application note include: • Overview • DMX512 protocol overview, including physical layer and data protocol • Software implementation with software flowchart, code description advantages and disadvantages of using interrupt or non-interrupt methods, interrupt- and non-interrupt-based code and DMX512 frame-detection code • DMX512 implementation constraints • DMX512 hardware implementation • Test considerations and conclusions
The full application note, DMX512 Protocol Implementation Using MC9S08GT60 8-bit MCU, is available as a PDF download from www.freescale.com/lighting.
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Freescale® and the Freescale logo are trademaks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. The HC08 products incorporate SuperFlash® technology licensed from SST. © Freescale Semiconductor, Inc. 2007 DOCNUMBER: BRHIBRIGHTLEDSOL / REV 1