FAQ's
1. Where can I buy Lednium
products?
2. What colours and products are available?
3. What colour temperature is your white
light?
4. Can I order other colours not specified
on your website?
5. What about UV and Infrared applications?
6. Why is your product different from other
LED products?
7. Is there a diagram available showing
output light [lm] vs. junction temperature?
8. What colour temperature options are available
for the white?
9. Will warm white (3500K) also available?
10. What CRI are you at for different CTs?
11. Are secondary optics available for
Lednium devices?
12. When will more application notes be
available?
13. Is heat management important like other
power LED products?
14. 25 lm/watt seems a little low these
days?
15. Customer wants to use 1.05A for max.
Power, but data sheet say mainly 0.65 A!!
1. Where
can I buy Lednium products?
Lednium products are available through our
partners. Please refer to our partner section on our website
for further information.
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2. What
colours and products are available?
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Lednium currently offers the following products
and colours as standard
Matrix Series: 9 Large Die/Chip Turtle
Red (625nm)
Green (525nm)
Blue (460nm)
Amber (595)
White (3500-7000K)
RGB (Red, Green, Blue)
Cup series: SMD and PSMD single die Cup
Red (625nm)
Green (525nm)
Blue (460nm)
Amber (595)
White (3500-7000K)
Please note that this is the base colour range,
other colours are available depending on quantities ordered.
Lednium products are currently aimed at power LED devices
so medium to large chips are used as standard, please refer
to data sheets. If smaller output devices are required due
to your application please contact us to discuss further.
Several new product designs and configurations are currently
under development so please check the website in the near
future for further product releases.
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3. What
colour temperature is your white light?
Lednium white light is currently aimed at
the cool/cold white light and has a temperature of around
7000ºK. We are currently in the process of producing
a daylight white light at around 5800°K and a warm white
light at 3500ºK. The type of white light you require
depends on your application. Warm white light produces a
relaxing (warming) effect on people, but its CRI is often
quite poor compared to daylight / cool white light.
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4. Can I order other
colours not specified on your website?
Yes light output and colour can be tailored
to your application. However production quantities must
be met so please call to discuss.
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5. What
about UV and Infrared applications?
Lednium products can be used with both these
types of die, please call Lednium to discuss.
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6. Why
is your product different from other LED products?
Lednium technology was designed based on the
immanent LED lighting future. We have incorporated in the
packaging design good heat dissipation and wide angle light
distribution from the onset. Lednium technology has the
added advantage of being able to easily adjust to changing
chip/LED sizes and technology, and flexible enough to adapt
to many applications.
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7. Is there a diagram
available showing output light [lm] vs. junction temperature?
Please refer to data sheets. Currently we show curves of
relative intensity v’s Temperature, but not total
Flux. Relative Intensity can easily be converted to lumens
because the turtle shape has a fixed distribution of flux.
The relationship between intensity (on axis) and total flux
is directly related to the shape of the flux distribution
curve. We calculate the total flux by measuring the intensity
distribution and integrating.
Since the Intensity v’s temperature curve is scaled
in a normalised (or per unit) way, by simply substituting
the lumen value at 25°C for Normalised Intensity = 1,
we can read off the actual value at any other temperature.
i.e change the scaling to total flux by interchanging total
flux for normalised intensity. Another way is to take the
normalised value at some temperature from the curves, and
multiply this by the quantified flux at 25C.
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8. What
colour temperature options are available for the white?
Refer question 3 above
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9. Will
warm white (3500K) also available?
Warm white light will soon be available and
CT (colour temperature) will be set between 3200-3800°K.
Please check data sheet/website regularly.
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10.
What CRI are you at for different CTs?
CRI (colour rendering index) data will shortly be release,
we are currently undergoing testing of our white products.
Warm white light and high CRI are incompatible so some compromise
depending on application has to be made by the user.
True white (colour co-ords 0.333, 0.333 theoretically gives
CRI = 100
If we design for CCT = 3000K, the co-ordinates on the black
body curve will be approx. 0.435, 0.405, and the CRI could
be < 20. We can design to be away from the black body
curve, but there will not be any increase in CRI. The question
you should ask yourself is, do we want to see colours close
to what they really are, or do we want to see everything
through ’rose coloured glasses’ ?
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11.
Are secondary optics available for Lednium devices?
Lednium is currently looking at both primary adaptation
of the lens to control light dispersion and also secondary
optics. It is possible to optically generate whatever beam
pattern suits the application.
Bearing in mind that the cup and turtle has
a finite size, it is conceivable to manipulate all the light
that is generated into a perfectly parallel sided beam of
the same size as the cup array, and at the other extreme
to have the light distributed as shown on the data sheets.
Lednium will release supplier and or product modifications
on the website when available.
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12.
When will more application notes be available?
We are currently reviewing application notes and will soon
be adding additional ones on the website. Please check website
in near future.
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13.
Is heat management important like other power LED products?
In short yes! All Power LED products on the market need
careful attention to thermal management. Heat management
must be considered on a case by case basis, every application
has different requirements and constraints.
We supply as much general information as available
on the current data sheets :
Thermal resistance of the package
De-rating curves for elevated ambient conditions (graph
and table)
Self heating curves (graph and table)
Junction temperature characteristics
A designer has control of how to apply these
parameters in the detail of each individual product.
Calculations of thermal performance and thermal modelling,
can be quite painstaking but software tools are available.
This is perhaps the least well understood area of design.
The simple answer is “get the heat to an outside surface,
along a thermal path of very low resistance”.
Any heat generator will continue to get hotter internally
until it reaches thermal equilibrium i.e. the heat generated
= the heat lost into the ambient air ……which
will ultimately be by radiation and convection.
If the surface which radiates the heat is at a temperature
close to that of the chip junction, then the thermal resistance
is close to minimum, and close to being optimised.
Practical guidelines –
Make heat sink big, maximise the surface
area
Make it black, shiny black surfaces are the best radiators
Use metal not plastic ( lower thermal resistance)
If at all possible make thermal contact with a larger item
Use a fan ………. if you can
Please check application notes in website for further information.
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14.
25 lm/watt seems a little low these days?
Chip and phosphor efficiency are constantly being reviewed.
Before making any change to a reportedly more efficient
emitter we must be sure of the quality and reliability.
The lumen values offered by other chip supplier and end
products suppliers should be treated as an indication, unless
you know the measurement process used. It is not uncommon
to have 5-10% error in measurements and also another 20-25%
variation due to measurement methods.
Lednium currently uses steady state values
on its data sheets, which shows real life operating light
output. Some competitors use impulse measurements that can
show 20% (or more) higher values than steady state measurements.
Lednium is reviewing its measurement process and any changes
will be added to the application note area of the website.
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15.
Customer wants to use 1.05A for max. Power, but data sheet
say mainly 0.65 A!!
Some of the earlier data sheets were conservative so as
not to overheat the die’s. The only products than
can be supplied at 1050mA are 9 cup turtles with large chips.
The appropriate data sheet lists the performance at this
value of current.
| |
Chip size |
Max. current |
| 9 chip Matrix series (Turtle) |
Large |
1050mA |
| |
Medium |
600mA |
| Small |
150mA |
It should be cautioned
that running turtles at 1 amp needs very efficient thermal
management or die’s will overheat. At this maximum
rating forced air or liquid cooling systems is highly recommended.
If this cannot be achieved please de-rate according to the
de-rating curves in the data sheet. Excessive high temperatures
at the die will reduce its light output and lifetime.
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