211 series
design considerations
Single-Chip LEDs
All devices feature water clear high intensity LEDs as standard. In devices where discrete LEDs are used, the single
chip LED devices have been modified by the removal of the domed portion of the encapsulation (flat-topped) to provide
even illumination of switches and annunciators. Non flat topped versions are also available.
Flat-topping does not apply to devices using surface-mounted device (SMD) LEDs.
Product Evaluation
Filament replacement LEDs have been specifically designed to meet the primary objective of providing improved reliability. As
this product range is suitable for both new-build and retro-fit, (sometimes in very old systems), a wide range of illuminated push
button switches and lamp holders can be encountered. Due to subjectivity, evaluation of the LED type is recommended,
(samples of all standard models are available). Care should be taken to correctly simulate operating ambient light conditions to
ensure that the correct device has been selected to maximise viewing characteristics such as viewing angle, colour
compatibility and on/ off contrast ratio.
Electro-Static Discharge (ESD)
Build up of electro-static discharge occurs in many situations involving people moving and handling products. The range of
possible situations is very diverse but voltage levels as high as several thousand volts can and do arise in many individual
situations. When an operator charged up to these levels handles a static sensitive device, there is a very probable likelihood
that the device will be irreversibly damaged. It is essential that precautions are taken at all stages during manufacture and
assembly of these products. Although LEDs were never considered to be static sensitive devices, changes in manufacturing
technology and materials used to produce higher intensity products over a large range of the wavelength spectrum have
changed this. Marl has an approved system of ESD control from goods in, through production and into final packing and
despatch. Marl recommend all users of LED based products follow the guidelines of BS 100015.
Power De-Rating
The forward voltage/ current value of an LED is dependant upon the ambient temperature of the environment in which it is
operated. Therefore, care must be taken to operate the LED at the correct voltage/ current values, depending upon the
ambient temperature. Consequently, a recommendation regarding operating voltages and currents is given in order to address
these temperature effects. This recommendation is termed ‘de-rating’. It is usual for forward voltages and currents to be
specified for ambient temperature of 25°C. However, because the values of these qualities vary with temperature, marl should
be contacted if the device is to be operated at a temperature significantly higher than 25°C. Marl accept no liability for any
product that is operated higher than the stated voltage.
to order
to order please contact us on: t:
+44 (0)1229 582 430
f:
+44 (0)1229 585 155
e:
sales@marl.co.uk
w:
www.leds.co.uk
© marl international limited technical documentation has been designed by marl international limited for the intention of
providing information, which must not be copied or released to a third party without prior written consent from marl
international limited. the information provided does not constitute part of any order or contract and should not be regarded as a
representation relating to either products or service. no responsibility can be assumed for inaccuracies or printing errors. marl
international limited reserve the right to alter without notice the specification or any conditions of supply for product or service.
BS EN ISO 9001:2008
approved manufacturer
marl international limited - dsn 211 - version 2012-12-06-113509
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MARL [ MARL INTERNATIONAL LIMITED ]
