Buck converter LED drive systems for automotive applications
In this second of a series of articles on power converters, Iain Mosely describes how the Buck converter switching topology can be used to drive LEDs efficiently in demanding automotive applications. Electronic systems operating in the automotive environment need to with stand high ambient temperatures and high-energy Voltage transients on the power source. Load-dump situations can result in around 60V or more being present transiently on a 12V power rail.
![]()
The example LED system presented in this article drives two Luxeon K2 LEDs at 1A from an input voltage of 10V to 65V with a nominal efficiency of 87%.
The switch is shown in Figure 1(a). When switch SW1 turns on, the voltage on node Vs is equal to the input voltage. When SW1 turns off, the inductive current flowing in L1 forces D1 to conduct and clamps The voltage on node Vs to be very close to zero. The resulting Vs node voltage waveform is a high frequency square wave as shown in Figure 1(b).
Inductor L1 and capacitor C2 form a low pass filter to recapture the DC (or average) value of the switching waveform. Whenever SW1 conducts current, it has zero voltage across it and when it blocks current, it has high voltage across it. In a highly efficient power-conversion process.
+++++++
This article was published in the September/October 2007 issue of LEDs Magazine.
To read the full version of this article, please visit our Magazine page, where you can download FREE electronic PDF versions of all issues of LEDs Magazine.
You can also request a print copy of LEDs Magazine (available by paid subscription) and sign up for our free weekly email newsletter . About the Author Iain Mosely is technical director of Converter Technology , a power electronics design consultancy focused on providing class-leading solutions For many different areas of power conversion including AC/DC, DC/DC, LED lighting and Power over Ethernet.![]()
October 2007 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 2004 2005 2006 2007 2008 2009 
The switch is shown in Figure 1(a). When switch SW1 turns on, the voltage on node Vs is equal to the input voltage. When SW1 turns off, the inductive current flowing in L1 forces D1 to conduct and clamps The voltage on node Vs to be very close to zero. The resulting Vs node voltage waveform is a high frequency square wave as shown in Figure 1(b).
Inductor L1 and capacitor C2 form a low pass filter to recapture the DC (or average) value of the switching waveform. Whenever SW1 conducts current, it has zero voltage across it and when it blocks current, it has high voltage across it. In a highly efficient power-conversion process.
+++++++
This article was published in the September/October 2007 issue of LEDs Magazine.
To read the full version of this article, please visit our Magazine page, where you can download FREE electronic PDF versions of all issues of LEDs Magazine.
You can also request a print copy of LEDs Magazine (available by paid subscription) and sign up for our free weekly email newsletter . About the Author Iain Mosely is technical director of Converter Technology , a power electronics design consultancy focused on providing class-leading solutions For many different areas of power conversion including AC/DC, DC/DC, LED lighting and Power over Ethernet.
Power X (Qingdao) Energy Technology Co., Ltd. , https://www.qdpowerxsolar.com