ID A21C: LED Lighting Control

1. ID A21C: LED Lighting Control The Basics 13 October 2010 Version: 1.2

2. BNS Solutions A little something about BNS… • Engineering consulting firm • Located in Walpole, Massachusetts • Renesas Platinum Alliance partner • Work in numerous industries including • Battery systems • Medical • White goods • Service industries • Avionics • LED Lighting • Entertainment • Industrial controls • Engineering Education • Embedded Tools • “Engineering and Technical Marketing Solutions as simple as possible, But Not Simpler™”

3. Greg Campbell • CTO, Lumenpulse Lighting • Design and manufacture cutting edge architectural solid state lighting fixtures involving complex and cost effective embedded systems • Responsible for all electrical product development and manufacturing, LED and technology roadmap, and strategic partnerships PREVIOUS EXPERIENCE: • Senior Embedded Systems Engineer at BNS Solutions • Electrical Engineering Manager at Philips Color Kinetics • BSEE from Virginia Tech Joe DiBartolo • Embedded Systems Engineer, BNS Solutions • Circuit and board design for LED lighting fixtures • Analog electronics background including power and signal processing • PREVIOUS EXPERIENCE: • BSEE from Boston University

4. Agenda • LED Lighting Overview • LED Binning Challenges and Compensation • Dimming and Control • Embedded Design Considerations • Renesas Solutions

5. LED Lighting Overview: Major Players

6. LED Lighting Overview: Market Considerations • Major Markets • Entertainment / Theatrical • Architectural Lighting • Retail / Office Lighting • Signage • Street Lighting • Applications • RGB • Early growth in entertainment space • Quick adoption into architectural lighting • White • Vast adoption following the growth in LED technology • Energy efficiency initiatives speeding up market penetration

7. LED Design Challenges: Binning • LED Manufacturing companies sort their product by “Bins” based on lumen output, chromaticity, and wavelength • Leads to complications in the board-level manufacturing process • Many ways to compensate: • SMT Line part placement • Calibration in software • Closed loop feedback

8. LED Binning (Cont’d) *CREE Inc

9. LED Binning (Cont’d) *EnLIGHTen Lighting

10. Binning Compensation • SMT line placement: • Treat different bins of LEDs as different components and place accordingly • Calibration Techniques: • Current Control • Use 1 bin per board • Constant current control • Power Control • Forward voltage implications over time and temperature • Adjust current real time to compensate for variation in forward voltage

11. Binning Compensation (Cont’d) • Feedback techniques: • Light sensor: • Sense light output and adjust power accordingly • Lifetime adjustment: • Use light sensor to detect reduced light output due to degradation of efficiency over long periods of time • Adjust power to achieve previous light output, extending the lifetime of the product • Lifetime considerations: • Thermal Management • Current and temperature relationship used to estimate lifetime • Measured by “L70” for white and “L50” for RGB

12. Dimming and Control • Control Methods: • PWM => Color Kinetics patent for RGB control • Triac and ELV dimmers for offline residential dimming applications • 0-10V Dimming • Control Protocols: • DMX512 • Industry standard originally evolved from the theatrical market • RDM • Bi-directional version of DMX • Dali • Digital dimming protocol • Very popular in Europe, not big market in North America • PLC (Power Line Communications) • Ethernet (Streaming ACN, Arknet, etc)

13. Dimming and Control • Demonstration

14. DMX512 • Physical Layer: RS-485 • 250kbps, start-bit, byte of data, two stop-bits, no parity • Break based for start-bit • Packet based w/variable length • Unidirectional implementation with no error checking/correction • Uses “RGB triplets” to set a dimming value • Can be 8 or 16 bit resolution of dimming value for resolving “stepping” between color settings

15. DMX512 (Cont’d)

16. PCB Design Considerations • LED lighting fixtures are usually serial in nature • Power is usually passed along the “daisy chain” along w/ data • Leads to increased difficulty in board-level designs to minimize losses • When designing for manufacturability, must provide for worst-case scenario • e.g. A 4 fixture chain powered by 24V @ 1A • Power only comes into first board so it must carry current for all other boards to the output connector • Size traces accordingly • Minimize distances between input and output • EMI Critical for offline applications • LED fixtures held to same EMI standards as traditional lighting sources • Difficult to design for EMI with PWM implications

17. PCB Design Considerations (Cont’d) • Thermal issues: • Transistors switching LEDs will generate heat • LEDs themselves generate heat (~25% efficient) • Thermal solutions: • Metal Core PCBs popular for heat dissipation • Mechanical integration key for heat sinking / thermal flow • Temperature monitoring via onboard thermistors • Thermal shutdown or compensation • Active over LED lifetime

18. Renesas LED Lighting Solutions Key Features HCD/LED Product line-up • 4-channels constant current LED driver (0.35–1.5A) • Buck or boost topology • 1MHz switching frequency • 9 – 38VDC input voltage • Protection circuit (over-current, over/under-voltage, thermal) • 32KB Flash, 8-bit MCU UPD78F8025 32KB Flash UPD78F8024 8KB Flash UPD168804/30 HCD/LED Driver only Enough flash for communication protocol (PLC, Wireless (802.15.4)) Drive multiple channels of LEDs for multi-color sequencing and simultaneous LED channels 8-/16-bit MCU Key Features 78K0/Ix2 Product line-up • Fast (40MHz) 16-bit inverter control timers • Up to four 40MHz 16-bit PWM outputs • 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 78K0/IB2 8KB-16KB, 30-/32-pin 78K0/IA2 8KB-16KB, 20-pin • Power factor correction (0.99 efficiency) • Regulate current for constant high-current drive • LED dimming control 78K0/IY2 4KB-16KB, 16-pin

19. Renesas LED Lighting Solutions • 78K0/Ix2 MCU: • Indoor and Outdoor Illumination and Commercial Displays • Replacement/ Retrofit to LED Light • Power Factor Correction from AC-DC conversion • Commercial Dimmer Support • Constant-Current HB-LED Drive • Network Lighting Control • DALI, DMX512, SPI to Wireless (ZigBee), Power-Line Communication • Intelligent Lighting Control, Programmability • Motion Detection, Light Sensor, Timer for Sequencing On-Off or Dimming • HCD-LED MCU (UPD78F802x): • Street Light • Multiple Channel HB-LED Driver – In case one or more channels of LEDs fail Network Lighting Control • SPI to Wireless (ZigBee, WAN), Power-Line Communication, Ethernet • Intelligent Lighting Control, Programmability • Light Sensor, Timer for Sequencing On-Off or Dimming, Thermal Management • Multi-Color LED Lighting • Multiple Channel HB-LED Driver for Multi-Color LEDs • Network Lighting Control • DALI, DMX512, SPI to Wireless (ZigBee), Power-Line Communication • Intelligent Lighting Control, Programmability • Color Sequence, Timer for Sequencing On-Off or Dimming

20. Questions?

21. Thank You!