2. The Crazy World of LED Dimming and
Control

3. 3
Or…
Why The #@*% Is It Doing That?!

4. • How LEDs work - understanding the basics
• How LEDs dim - different approaches
• What happens when LEDs dim - color, life, efficiency, flicker, noise
• Matchmaking - how to get LEDs, drivers and controls to work together
• Application do’s and don’ts
4

5. 5
Natalia Lupacheva
Systems Engineer
ETC, Middleton, WI
Greg Smith
Director of Product Development
Tivoli, Tustin, CA
Presented by:
Gary Dulanski
Principal
The Dulanski Group, NYC

6. 6
Outline
Gary Dulanski
• Basics of LEDs: how they work, voltages and currents, AC
and DC
• Define drivers and power supplies
• Dimming retrofit LED lamps versus LED fixtures
• Light output vs energy saving when dimming LEDs
• LED life when dimming
• LED color when dimming

7. 7
Outline
Natalia Lupacheva
• Dimmer - Driver - LED interactions
• Phase Control dimming - forward and reverse
• AC + Control Signal dimming - 0-10v, DALI, DMX
• Dimming techniques - Pulse Width Modulation, Constant
Current Reduction
• Flicker issues
• Turn-On behaviors
• Dimmer load restrictions
• NEMA SSL-7A Standard

8. 8
Outline
Greg Smith
• Visual effects
• Range of control, minimum output
• What happens to color when you dim LEDs
• Advantages when using LEDs vs other sources
• Range of LED whites and colors
• Variable / Dynamic white color control
• Warm shifting
• Color tuning
• Lumens vs color
• Automated controls

9. 9
Q & A
• Clarifications anytime
• Big Questions at the end

10. 10
Basic Electricity
• Conductors
• Insulators
• Voltage = Pressure
• Current = Flow
• Load Has Resistance
• Current = V / R
• Power = V x I
• DC = Direct Current,
Current Flows One Way

11. 11
AC
• AC = Alternating Current,
Current Flows Two
Directions
• Frequency Hz

12. 12
Diodes
• SemiConductor
• Diode Conducts Only One Way
• Threshold Voltage To Conduct
• Rectifies AC

13. 13
Light Emitting Diodes
• Electroluminescence
• 1962 Red LED - gallium arsenide
phosphide
• Indicator Lights
• Fast - Fiber Optic Telecommunication

14. 14
LED Circuit• Threshold Voltage To Overcome ~1-3 V
• Limit Current
• Only DC
• Efficiency; consider loss in the limiter

15. 15
Series LED Circuit
• Multiple LEDs Connected
• Higher Supply Voltages
• Efficiency, Less Loss
• One Fails = All Go Out
• Think: Turn On Threshold and Dimming

16. 16
Parallel LED Circuit
• Multiple LEDs
• One Fails, Others Keep Working
• Think: Lower Voltage, Higher Current

17. 17
LED Array
• Series + Parallel
Together
• Screen Backlight Vs
Individually
Controlled LEDs In A
Video Display

18. 18
Driver
• Transform Voltage
• Convert AC To DC
• Drive Correct Current To
LEDs
• Smooth Output
• Compensate For Power
Fluctuations

19. 19
LV Power Supply + Driver
• Line Voltage Converted
To Low Voltage
Separately, Low Voltage
Fed To Fixture
• Driver Circuitry Built Into
Fixture

20. 20
LED Retrofit Lamp
• Driver Built In

21. 21
Dimmable Driver
• Transform Voltage
• Convert AC To DC
• Vary Current To LEDs
• Smooth Output
• Compensate For Power
Fluctuations
• Don’t Misbehave
• Line Voltage Dimmers
DIMDIM

22. 22
DIMDIM
Dimming Driver
• Transform Voltage
• Convert AC To DC
• Vary Current To LEDs
• Smooth Output
• Compensate For Power
Fluctuations
• Don’t Misbehave
• 0-10v, DALI, DMX, 3-Wire Line
Voltage

23. 23
Light Output vs Power
• Depends on LED and
its cooling
• Heat affects efficacy

24. 24
Dimming Performance
• Range Of Dimming ?
• Turn On Behavior ?
• Dimming Curve ?
• Flicker ?
• Eye Response: Perceived
Light = Square Root of
Measured Light

25. 25
Light Output vs Time & Temp
• See DOE Caliper
Testing Reports
• Heat Degrades
• L90, L70
• Cooler LEDs shift less

26. 26
Dimming White LEDs
• Blue + Phosphor
• Lighting Research
Center Study:
Chromaticity Shifts Due To
Different Dimming Methods

27. 27
Dimming White LEDs
• Lighting Research Center Study: Chromaticity Shifts Due To
Different Dimming Methods
• CCR Chromaticity shift yellow • PWM Chromaticity shift blue

28. 28
Color vs Time
• What The …

29. 29
OLED - Organic LED
• Organic Semiconductors
• Thin
• Flexible
• Lifespan

30. 30
Natalia Lupacheva - ETC
• Dimmer - Driver - LED interactions
• Phase Control dimming - forward and reverse
• AC + Control Signal dimming - 0-10v, DALI, DMX
• Dimming techniques - Pulse Width Modulation, Constant
Current Reduction
• Flicker issues
• Turn-On behaviors
• Dimmer load restrictions
• NEMA SSL-7A Standard

31. Natalia Lupacheva
ETC

32. 1. Coincident AC power and
control signal
• Phase-cut dimming
- forward phase
- reverse phase
2. Separate AC power and
control signal
• Fluorescent 3-Wire
• 0-10V
• DALI
• DMX512

33. Dimmers reduce the RMS voltage
delivered to the lamp by removing
a portion of the AC waveform from
forward or reverse phase.

34. • Dimmers reduce the RMS voltage
delivered to the lamp by removing a
portion of the AC waveform from the
forward phase, or leading edge.
• Designed for resistive
(incandescent, halogen) or
magnetic low-voltage (MLV) loads.
cuts off the front side of the
wave

35. • Dimmers remove a portion of the
AC waveform from the reverse
phase, or trailing edge.
• Originally designed to improve the
performance of low-voltage
halogen lamps operating on
electronic transformers.
cuts off the back end of the
wave

37. • Separate AC power and control
signal (phase-cut hot control
signal)
• Smooth dimming
• Stable over long wire runs
• Allows for maximum circuit
loading
• Impossible to assign individual
control to one or many light
fixtures without rewiring

38. • Fairly smooth dimming of
LED fixtures
• Control zones can be run
separate from power
zones (requires two extra
low voltage wire runs)
• Long wire runs can affect performance (e.g. dimming range, accuracy)
• Two 0-10V standards exist. Use of components complying with different
“standards” results in interoperability problems.
• Impossible to assign individual control to one or many light fixtures without
rewiring

39. 0-10V using ANSI E1.3
• Control sources the current
• Load sinks the current
• 10V = 100% light
• 0V is off
0-10V using IEC 60929
• Load sources the current
• Control sinks the current
• 10V or above = 100% light
• 1V or below= minimum light

40. • Two-way communication
• Easy to assign individual
control to one or many
light fixtures without
rewiring
• Simple interface BMS.
• Easy modifications
•Many manufacturers have “proprietary” extensions
•Requires two low-voltage differential wires
•Requires extra commissioning and installation time

41. • Two-way communication system that brings digital technology to
lighting
• DALI defines the commands that ballasts need to recognize in
order to be considered DALI ballasts
• Allows for a maximum of 64 fittings on a single network

42. • DMX512 is a serial protocol used to control lighting equipment
like dimmers, stage lighting and theatrical effects (ex: moving
lights, color changing lights, fog machines, etc.)

43. • Controls, luminaires, and wiring have to comply with the
standard
• Available in wireless implementations as well (WDMX)
• Two way communication between
controller and DMX device (with RDM)
• Requires two low-voltage wires for
control
• Addressing of up to 512 channels per
data link or “universe”
• Easy to assign individual control to
one or many light fixtures (devices)
without rewiring

44. Whether separate or integral, the driver electronics determine the
dimming performance of an LED source
Two common methods of dimming LEDs:
•Pulse Width Modulation (PWM)
•Constant Current Reduction (CCR)
LED sources require a “driver””

45. A PWM based LED dimming driver pulses the LEDs on and off at
a rate of about 240 pulses per second.
• Cameras pick up the pulses - looks like
strobing.
• Potentially undesirable flicker
• Power supplies are more complex and
expensive to manufacture.
• PWM drivers may experience
performance issues if mounted remotely
from the light source
• Provide very precise output level – good
for color mixing
LED dimmed to approximately 25% using PWM

46. • No noise generation
• Does not create flicker
• Longer wire runs between the driver and
the light engines.
• Color shift below 40%
CCR (analog) driver sends a varying amount of current to the LED
LED that is reduced to approximately 25% using CCR

47. • Flickering (hovering)
• Flashing/strobing
• Pop-on
• Drop-out
• Dimming smoothness
• Popcorn
• Audible noise
• Dimming range
• Dimmer loading
• Premature failure of dimmer
and/or LED load
• Ghosting

48. 100 lamps on a circuit at control level 75%.
• Flashing from dimmed level to
Full
• Flashing from dimmed level to
Off
• Hovering (flickering, fluttering..)
• Acting like non-dim (On or Off)
• Full to Off or Off to Full

49. Problem:
Flashing from dimmed level to Full
Reason:
The load is too capacitive for the FPC
(Forward Phase Control) dimmer
Problem:
Flashing from dimmed level to Off
Reason:
Load is not big enough (resistive) for FPC
(Forward Phase Control) dimmer.
Problem:
Acting like non-dim (on or Off)
Reason:
1. LED lamp is not designed to dim
2. Not enough load on a circuit
Problem:
Full to Off or Off to Full
Reason:
Not enough load on a circuit

50. When Voltage amplitude changes dimmer tries to compensate by regulating the turn
on time to keep the same RMS voltage.
Problem:
Hovering (flickering, fluttering..)
Reason:
1. Change in Line voltage
2. LED lamp is not designed to dim (or dim
well)

51. Reason: lamps aren’t made the
same

52. • Created by connection to power,
occurs once per power-up
• Can be 100’s x Irms
Inrush is 65 times higher than rated RMS current.
• Excessive wear on switch or relay
contacts
• Chokes can help to minimize inrush to
dimmer

53. • Created by forward phase-cut, occurs
every half-cycle
• Commonly 5-10x Irms; can be much
higher

54. • Major factor determining maximum
dimmer loading
• Major contributor to audible noise in
light sources and controls

55. • A very brief spike in voltage (above the
instantaneous line voltage) caused by
the discharge of energy-storage
elements
• Can cause long-term damage to
voltage-sensitive components in the
dimmer or lamp
• Caused by interaction between
dimmer and lamp

56. • Noise can come from the dimmer
itself (If the existing dimmer cost
less than $20, try a dimmer that
uses a toroidal filter or a densely
wound bar choke)
• Noise can come from the lamp
(caused by interaction between
dimmer and lamp)

57. • Issue with MR16 lamps retrofits
• Two compatibility requirements
• Loading requirements
• Transformers designed for
resistive loads

58. • Interaction between dimmers and LED light engines
• It is not intended to be used to determine compatibility with existing
(non-compliant) products

59. Marking requirements
Dimmer
•Maximum rated wattage
•Minimum load
•Type 1/Type 2 compliance
•How to set SSL-7A load type
•LLE
•Minimum light output
•Type 1/Type 2 compliance

60. • LED product evolution is rapid and product generation life is short
• The LED driver determines dimming performance
• Compatibility must be determined BEFORE products are ordered and installed
• Questions to ask:
- Is the LED product a lamp or luminaire?
- Designed (claimed) dimming performance of the LED?
- What type of control signal is LED designed for?
- Does LED product have a recommended dimmer list,
control type, dimmer loading requirements, etc…
• Perform Mockups

61. Dimming quality
characteristics such as lack
of flicker, smoothness, or a
specific minimum dimmed
level are best evaluated by
observation, which is why
mockups are so strongly
recommended.
If a mockup is not possible,
use a proven combination of
LED sources and dimmer.

63. Presented by:
Greg Smith
Tivoli, LLC

64. 64
Greg Smith - Tivoli
• Visual effects:
• Range of control, minimum output
• What happens to color when you dim LEDs
• Advantages when using LEDs vs other sources
• Range of LED whites and colors
• Variable / Dynamic white color control
• Warm shifting
• Color tuning
• Lumens vs color
• Automated controls

65. • Maximum Lumens are dictated
by circuit design and operating
current
At 350m A – Decisions
need to be made…
Higher Lumens by
Driving current Higher
Trade Off:
•Heat Output
•Life and more

66. • Minimum Output is based on visual
illumination point
• Dimmer setting value vs.
illumination value percentage
• Low end of output cuts off at 10%
to 20%.
• Based on Dimmer setting Value
vs. illumination percentage value
Minimum Output

67. • Dimming via PWM:
• Maintain color but have an underlying
“flicker” or “shimmer” while CCR dimmed
LEDs can show a shift in color but
remain smooth.
• What applications makes sense for
each type of dimming?
• LEDs add a new feature to dimming
with adjustable intensity with controlled
color
Source: Electrical Contractor

68. • Incandescent / Halogen
• Fluorescent
• LED Warm Whites
• LED Colors

69. Sources warm along the Black Body
Line as the intensity of the light is
reduced.
This has become the model for
residential and entertainment lighting
that LED technology has been moving
towards.

70. • Have the same adjustable
intensity without the color
shifting qualities of
Incandescent
• Ideal for signage, decorative
and constant illumination
space applications that LEDs
have been able to move into
very well.

71. LED White colors feature
•Beautiful High CRI
•Tight binning
•Even warm 2200ºK color

72. Same dimming
characteristics as
White LEDs

73. Photo Credit: LED
Can we do this
with whites?

74. Defined as illumination that mimic the
dimming curve of incandescent light
sources.

75. • Single circuit
• Mimics incandescent sources, warming
color shift as light intensity decreases
• There are limitations of this simple set up
and the affects on Lumens and Color
range
• Set up using 2 colors of LED in the same
fixture space
• Dimming is controlled with the Warmer
color at 100% illumination at all times
• Dimming control is connected to the Brighter
LED circuit

76. • Work with programmed
controllers or IC chips to
adjust both colors in a
way that mimics the Black
Body curve without the
color Lumens limitations
of the simple Dim to
Warm.

77. Variable White is similar to our simple Dim to Warm set up except
that both LED colors are connected to controllable dimming circuits.
This can be done in both simple and smart controlled methods.

78. • Based on 2 color LED mix.
• Low end warm white
• High end cooler white
• Connecting to the 2 LED
colors as separate dimming
control circuits allows the
user to dial in a color based
on intensity levels of each
circuit.

79. • Control allows
preprogrammed
settings that dial in both
the color mix and
lumens desired for the
lighting with a single
interface

80. • 4-circuit control
• Offers wider range of color mixing with
variable lumen output and color
temperature
• Dynamic whites are based on the use
of White, Red, Warm White and Yellow
LEDs.
• There can be variances from different
manufacturers of what CCT is used for
the White and Warm White and even
the wavelengths of the Red and Amber
LEDs.

81. • Already available in some
down light fixtures
• Includes all of these LED
colors and intelligent internal
control
• Creates an illumination that
directly follows the Black Body
line curve
• All Inclusive
• Controllable White
Source: CREE –
preset Sunset
Dimming

82. • DMX controls creates color
contrasts and uniformity between
different fixtures within the same
space almost regardless of
manufacturer and ambient color
reflections.
• Knowing the ingredient colors of
the Dynamic LED sources and
checking that they match
between fixtures will help to
ensure that uniformity can be
achieved.

83. What is more important?

84. • Can other control
applications like external
triggers be the vehicle
for changing the color?
• Change in Intensity
• What about Color?
Motion sensors
Photo Cells
Timers

85. 85
• How LEDs work - understanding the basics
• How LEDs dim - different approaches
• What happens when LEDs dim - color, life, efficiency, flicker, noise
• Matchmaking - how to get LEDs, drivers and controls to work together
• Application do’s and don’ts

86. 86
Panel: Do’s and Dont’s,
Questions and Answers
Gary Dulanski
The Dulanski Group
Natalia Lupacheva
ETC
Greg Smith
Tivoli

87. 87
Gary Dulanski
The Dulanski Group
Natalia Lupacheva
ETC
Greg Smith
Tivoli
Thank You!
Please Fill in Evaluations!

88. 88
Flicker, Buzz and Color Change
The Crazy World of of LED Dimming and Control
March 19, 2014