With lighting devices consuming around 19% of the world’s total electrical power, many countries are phasing out the sale of inefficient incandescent lamps as part of their energy conservation efforts.
According to industry reports, over 8000 billion incandescent lamps were sold in 2012, which amounts to about 45% of total lighting sales.
The United States, China, Russia, and Brazil started banning sales of incandescent light bulbs up to 60W in 2014, putting the conversion of residential indoor lighting from incandescent to LED well on track. Meanwhile, advancements in LED technology and improvements in production costs will most certainly accelerate the growth of the LED lighting market.
The table below highlights the higher efficiency and longer lifetime benefits of LED lighting over incandescent lamps.
The development of LED lighting power supply systems focuses on higher efficiency, dimming control and lower cost. It was these factors that Fairchild had in mind for LED lighting with the release of our 800V SuperFET® II MOSFETs.
In the 10W ~ 100W LED power supply system below, a modified flyback topology is being used with an 800V MOSFET mainly applied as a switch.
System makers determine the MOSFET voltage rating by adding a 20% BV(Breakdown Voltage) margin to account for the possibility of abnormal input voltage and transformer turn ratio distribution, and other variations.
The waveform below shows the maximum MOSFET voltage of 609V in the actual LED lighting system at Vin 264Vac. Therefore, an 800V MOSFET should be used.
Fairchild’s 800V SuperFET II MOSFETs for LED lighting are shown below.
(suffix “Z” : Zener diode b/w gate and source, “L1”: TO220F narrow outlead, “YD”: Y form of outlead)
As you can see from the table, Fairchild’s 800V SuperFET II MOSFETs come in a wide range of standard package options. DPAK(TO-252)/IPAK(TO-251) are recommended for size-constrained retrofit LED lamps and PAR LED lamps, and TO-220/TO-220F for LED down lights and LED street lights.
The 800V SuperFET II MOSFET uses the latest super-junction technology to enable a small form factor with the industry’s lowest on-resistance (RDS(ON)) and output capacitance (Coss) for delivering higher efficiency than ever before.
Additionally, an embedded zener diode between the gate electrode and source electrode of the 800V SuperFET II MOSFET increases ESD immunity, which improves system reliability by protecting the device from high surge voltage caused by lightning.
The table below compares 800V Super Junction MOSFET characteristics.
Note that the FCPF400N80Z has lower Qgd and Eoss (the energy loss of output capacitance) than competing solutions.
The graphs below show the evaluation test results and power dissipation analysis with the above 3 Super Junction MOSFETs in a 100W flyback system.
The FCPF400N80Z works with lower power dissipation due to lower switching power dissipation during MOSFET turn on and turn off. Also, 800V SuperFET II MOSFETs deliver a robust, built-in diode at high di/dt and dv/dt conditions during built-in diode turn off.
The waveform below shows the reverse recovery current of the built-in diode.
The robust built-in diode can improve system reliability when the MOSFET operates in non-zero voltage switching mode, such as in an output short mode bridge circuit.
With their small form factor, high efficiency, and robust reliability, Fairchild’s newly released 800V SuperFET II MOSFET will go a long way toward helping makers of LED systems to improve efficiencies and spur continued adoption for a cleaner planet.
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