Many Light Emitting Diodes (LEDs) are typically required to source sufficient light for automotive exterior applications. Maintaining even illumination requires the drive current to be well controlled for all the LEDs in an array. This can be challenging in the voltage driven automotive environment when dual level operation is desired, such as for combined stop and tail function. A current source in the form of an LED Driver Module (LDM) can be employed to drive the LED array. However, a passive resistor network may be capable of driving the LED array with a reduction in both cost and complexity when compared to an LDM solution. The advantages and disadvantages of various passive resistor network configurations for dual level operation will be examined. Achieving dual level output from an LED array can be challenging. The low current behavior of LEDs leads to the possibility of a wide range of flux output if the current to the LEDs is not properly controlled. In addition, even with good current control, the range of output of the LEDs at low current is expanded leading to an even wider range of expected array output. It is for these reasons that the LED manufacturers typically recommend that low flux operation be achieved by driving the LEDs with relatively high current and a reduced duty cycle via Pulse Width Modulation (PWM). This study shows, however, that if the additional features and complexity of an LED driver module are neither desired or required, adequate current control of a dual output array of LEDs can be achieved by using a suitable passive resistor network.
Effectively driving led arrays with passive electric circuits for dual function automotive applications
Effektive Ansteuerung von LED Arrays mittels passiver elektrischer Schaltkreise für automobile Anwendungen mit Doppelfunktion
2004
7 Seiten, 9 Bilder, 2 Tabellen, 3 Quellen
Conference paper
English
British Library Conference Proceedings | 2004
|SAE Technical Papers | 2004
|Automotive engineering | 2004
|British Library Conference Proceedings | 2004
|Automotive Applications: Passive Components
British Library Conference Proceedings | 2001
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