LED drivers Phosphor technology - Beriled

Reliability of electronics
The quality of driver electronics has to be on a very high level to compete
with lifetime of the LEDs. Especially for embedded systems when the
driver and LEDs are mounted on the same circuit board this is
necessary:
•
Passive electronic components sometimes don’t have the lifetime
or robustness of LEDs.
Save system operation
The driver electronics should prevent damage of the LEDs because of
thermal issues under all circumstances.
•
Closed loop feedback systems, with voltage and current control
and thermal sensors are necessary.
Dimming capability
Dimming opportunities are desirable for white LED lighting and in
particular for RGB, RGBW or RGBA LED clusters to adjust colour, CCT
and CRI. The free choice of colour or CCT is one of the most interesting
features of LED lighting.
•
•
•
•
Costs
Analogue dimming leads to colour drift.
For 1% dimming a RGB system covering the full colour range
PWM duty cycle must have a range of about 1:10.000.
Switching losses of a PWM system stay almost constant at low
dimming levels, hence system efficacy decreases.
For highly accurate lighting systems costly closed loop feedback
systems with optical sensors are necessary.
Depending on the application costs are very critical, especially for
replacement of today’s low voltage halogen systems high quality low
cost solutions are necessary.
•
•
Replacement: AC/DC 12V systems with magnetic transformers and
switch mode power supplies must be served.
Replacement: Dimming should be possible anyways.
Copyright © 2007 Luger Research & LED professional. All rights reserved.
Patent infringement
Lots of patent applications for LED systems were published during the
last decade. Many are really basic that some technician wonders that
they were granted, others are really ingenious and it is hard not to use
the presented solution:
For many applications PWM would be the first choice, but for
some applications this technology is blocked by the CK patent
US6016038.
Calculation and transformation algorithms for fast and accurate
colour settings are also blocked by different granted patents.
DRIVER IC MANUFACTURES
Allegro MicroSystems, Inc. http://www.allegromicro.com
Austriamicrosystems http://www.austriamicrosystems.com
Clare Micronix http://www.claremicronix.com
Dialog Imaging Systems GmbH http://www.diasemi.com
FAIRCHILD Semiconductor
GmbH
http://www.fairchildsemi.com
International Rectifier http://www.irf.com
Linear Technology Corporate http://www.linear.com
Maxim Integrated Products,
Inc.
http://www.maxim-ic.com
Micrel Inc. http://www.micrel.com
Microchip Technology Inc. http://www.microchip.com
Monolithic Power Systems http://www.monolithicpower.com
National Semiconductor http://www.national.com
NXP Semiconductors http://www.nxp.com
ON Semiconductor http://www.onsemi.com
Power Integrations http://www.powerint.com
Sipex Corporation http://www.sipex.com
STMicroelectronics http://www.st.com
Supertex Corporate http://www.supertex.com
TOKO Ltd.
http://www.toko.co.jp/top/en/index.
html
Vishay Intertechnology, Inc http://www.vishay.com
Zetex Semiconductors plc http://www.zetex.com
www.led-professional.com LED professional Review | June 2007 | page 15
•
•