Download LED Lighting Control - Renesas E

ID A21C: LED Lighting Control
The Basics
Greg Campbell
Chief Technology Officer Lumenpulse Lighting Inc
Joe DiBartolo
Embedded Systems Engineer BNS Solutions
13 October 2010
Version: 1.2
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™”
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
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Agenda
 LED Lighting Overview
 LED Binning Challenges and Compensation
 Dimming and Control
 Embedded Design Considerations
 Renesas Solutions
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LED Lighting Overview: Major Players
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LED Lighting Overview: Market Considerations
 Major Markets
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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
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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
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LED Binning (Cont’d)
*CREE Inc
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LED Binning (Cont’d)
*EnLIGHTen Lighting
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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
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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
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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)
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Dimming and Control
 Demonstration
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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
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DMX512 (Cont’d)
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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 worstcase 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
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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
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Renesas LED Lighting Solutions
HCD/LED
Product line-up
UPD78F8025
32KB Flash
UPD78F8024
8KB Flash
UPD168804/30
HCD/LED Driver only
8-/16-bit MCU
78K0/Ix2
Product line-up
78K0/IB2
8KB-16KB, 30-/32-pin
78K0/IA2
8KB-16KB, 20-pin
78K0/IY2
4KB-16KB, 16-pin
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Key Features
 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
Enough flash for
communication protocol
(PLC, Wireless
(802.15.4))
Drive multiple channels of
LEDs for multi-color
sequencing and
simultaneous LED channels
Key Features
 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
• Power factor correction (0.99 efficiency)
• Regulate current for constant high-current drive
• LED dimming control
Renesas LED Lighting Solutions
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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
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Questions?
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Thank You!
Renesas Electronics America Inc.