We like solving hard problems at Liteline. Dimming LEDs requires just the right amount of finesses, engineering and common sense to deliver a beautiful experience for your lighting design. Check out how dimmer's work and how we integrate them into our Liteline products.

1. Daniel Silverstein
DIMMING LEDs: CHALLENGES & SOLUTIONS
NATIONAL SALES CONFERENCE 2016

2. Dimming LEDs

3. Things We Need to Know
1. What is AC vs DC Power?
2. How Do Dimmers Work
3. What is an LED driver, and what does it do?
4. What's the difference between Constant Current and Constant Voltage?
5. How has Liteline simplified all of this so we don’t have to worry about it?

4. AC vs DC Power:
A Quick Refresher
AC = Alternating Current
Kayak strokes are Left / Right but
they add up to forward motion
Pass through a 0 phase with no
power, motion does not stop

5. How Does a
Dimmer Work?
A dimmer reduces power by
increasing the amount of time
the power is “off”
Forward Phase, Leading
Edge or TRIAC dimmers cut
off the first part of the cycle
Reverse Phase, Trailing Edge
or ELV dimmers Cut off the
second part of the cycle

6. What is an LED Driver?
Constant Current:
Supplies a fixed current 300mA, 1.2A etc.
Used when the load is known, ie 1 fixture per driver
Wired in series – The output is fixed so the power is
divided by the number of LEDs
Dimming is achieved by reducing output current
Constant Voltage:
Supplies a fixed voltage: 12v, 24v 36v etc
Used when the load is not known ie 96w MAX –
Puck lights, Step lights, LED Tape etc.
Fixtures are wired in Parallel.
As the load increases the current increases
Dimming is really tricky
An LED driver is an electrical
device which regulates the power to
an LED or a string (or strings) of
LEDs. An LED driver responds to
the changing needs of the LED, or
LED circuit, by providing a constant
quantity of power to the LED as its
electrical properties change with
temperature. 1

7. How Do Dimming
Drivers Work?
1. Convert AC to DC Power
2. Use chopped AC sine
wave to trigger output
power reduction
3. ????
4. Profit!
A Bicycle converts the alternating pedal
strokes into constant forward motion at
the wheel
Q: How can you slow down the bike if
you still need to pedal 60 times per
second?

8. Trigger Signals
The sine wave on and off switch is
correlated as a percentage of power
By measuring the amount of time that the
power is in the 0 state we can modify the
output to match the required light levels
Flickering can be caused in Leading edge
if the trigger signal is shorter than the
amount of time until the next cycle
For leading-edge dimmers, once triggered, a triac or thyristor relies on the current
flowing through the device to keep it conducting. If the current falls below the device’s
threshold level (i.e., the zero crossings of the AC waveform), it will turn off and stop
conducting. However, with an inductive load, the current lags behind the voltage so it’s
possible that the current through the triac will not reach the triac’s threshold level before
the trigger pulse ends. This results in unacceptable dimming performance. To avoid this
issue, dimmers designed for use with wire-wound transformer loads use a triggering
technique known as a “hard firing.” This ensures the trigger pulse is maintained for a
long enough period of time to make certain that the current reaches the device’s
threshold level.

9. The Driver – Inputs and Outputs
In order to dim properly, an LED
driver needs to be matched with
a compatible type of sine wave
modulation
Using a dimmer on a non-
dimmable driver is like trying to
slow down a ‘fixie’ by ‘gliding’
Searching for ‘Fixie Fails’ on
google is a lot of fun

10. Different Types of LED Drivers
Constant Current:
Drivers are fairly simple to dim
Output voltage and current are
fixed values, current is reduced by
appropriate amount
Constant Voltage:
Really Difficult
If current is a function of the load,how do you
adjust the output so that it works at 1w, 20w
and 96w without flickering?

11. Solution 1 – Magnetic Drivers
Root Mean Squared (RMS)
Not True DC
Voltage Averages 24v
Vpk is 33v
Sine Wave is rectified to 120hz
Chopped input sine wave = chopped output
Disadvantages:
low frequency can result in flickering
Poor low level dimming
RMS results in reduced light output
Vpk can damage resistors and other components causing
dramatically shortened lifespan

12. Solution 2 – Electronic Driver
How does it work?
Input trigger voltage results in reduction of output voltage
True DC output
35kHz
0.5w min load
1% dimming
Unlimited distance from fixture to driver

13. Sigma Series Program Bounce light off walls for shadows and texture
Use narrow beam angles to create contrasting patterns
Backlight | Frontlight | Uplight |Sidelight | Downlight

14. Wall Light Ideas

15. Lighting Solutions With
Dimming Constant Voltage LED Tape Light

16. Liteline.com