Scheme of LED lighting driver with different power supply and different power levels

With the development of LED technology, the application of LED has been extended from the traditional low-power portable products to the high-power indoor lighting, outdoor lighting and flashlights. According to the different driving power, LED lighting can usually be divided into AC - DC (AC-DC) LED lighting, DC - DC (DC-DC) LED lighting power supply and battery power LED flashlight and other different types of LED lighting and its power are different, such as 3 W, 3 PAR16 * 2 W PAR20, 10 W/15 W PAR30 W/22 W, 15 PAR38, 1 W G13, 3 W GU10, 1 W, 3 MR16, 3 MR11 W W/9 W/15 W downlight, 1W-3W reading lamp etc..

1, AC-DC LED lighting solutions in the LED A Morimi semiconductor lighting application of AC-DC power supply, to provide a variety of off-line controller and power factor correction (PFC) controller, and with the isolation and non isolation requirements to provide different LED application scheme. There is no physical and electrical connection between the AC line voltage and the LED, the common topology is the flyback (Flyback) and double inductance plus single capacitor (LLC) half bridge resonance. Different topologies are suitable for different power ranges or for special design requirements. For example, the flyback topology is less than 100 W for low power applications, while the LLC half bridge topology is the preferred solution for high power and high efficiency.

Figure 1: isolated topologies with different power ranges

AC-DC LED lighting applications, low power LED applications are usually driven by constant current (CC), and constant voltage (CV) function is in the case of open circuit as a protection function. The application of LED high power may need to be added in the circuit of power factor correction (PFC), the AC-DC conversion and LED driver circuit part two can use integral (integral) configuration, namely the two together, are located in the lighting, can also be used in distributed (distributed) configuration, as shown in figure 2, then to simplify security considerations, and increase the flexibility of the system. Figure 2: distributed high power LED driver (distributed) configuration

From the aspect of the application scope of specific power supply scheme, LED lighting application of AC-DC mainly include: 1 W-8 W:G13/GU10/PAR16/PAR20 8W -25 W:PAR30/PAR38 lighting lighting 50 W-300: W area lighting

1) 1 W-8 W AC-DC LED lighting application of this kind of input voltage application requirements for 90 to 264 Vac, the efficiency reached 80%, to provide short-circuit protection, overvoltage protection and other protection characteristics at the same time, and provides 350 mA and 700 mA constant current applications including G13, GU10, PAR16, PAR20 and embedded lights (downlight) etc.. This kind of application can be used in A Morimi semiconductor NCP1015 self powered monolithic switching regulator. This device integrates the fixed frequency (65/100/130 kHz) high voltage MOSFET current mode controller and 700 V, with all the characteristics of building low cost strong power required, such as soft start, frequency jitter, short circuit protection, skip cycle, the maximum peak current set point and dynamic self supply function (without auxiliary winding) etc.. Figure 3 shows the circuit diagram of the NCP1015 in the isolated W-8 1 W AC-DC LED lighting applications. It is worth mentioning that, NCP1015 also can be used for non isolation type (circuit without transformer) AC-DC LED 1 W-8 W lighting application range, the circuit can be used to tap (tapped) inductance to improve the MOSFET work duty ratio, and improve the system efficiency and the performance of the circuit. Figure 3: A Morimi semiconductor 8 W LED driver application circuit with an input voltage of 85 to 264 Vac

2 (W-25) W AC-DC LED lighting applications, the United States Department of energy (DOE) "Energy Star" (ENERGYSTAR) solid state lighting (SSL) specification shall be mandatory to provide power factor correction (PFC) at any power level. This standard applies to a range of specific products, such as lights, cabinet lights and table lamps, in which the residential application of the LED driver power factor must be greater than 0.7, while commercial applications should be greater than 0.9. But this standard is voluntary, that is, the choice of non-compliance or compliance. Accordingly, in 8 W-25 W LED AC-DC lighting applications, we consider the situation of the two, one is the application of no power factor requirements, that is, without the use of PFC controller, and the other is the need to use PFC controller. The application does not require PFC, we assume that the input voltage specifications for 90~132 Vac or 180~264Vac (or universal input), energy efficiency up to 85%, to provide short circuit protection and open protection characteristics, the output current is 350 mA, 700 mA and 1 A constant current, the conductor can use Amori Mihan NCP1028 or NCP1351. Among them, the NCP1028 is an enhanced monolithic switching regulator, suitable for use in general purpose power supply applications to provide a few watts to 15 W output power. The NCP1028 is lower than the NCP101x, providing 800 mA peak current, with many of the characteristics of the NCP101x, but also provides over power protection, built-in slope compensation and input undervoltage protection and other characteristics. NCP1351 is a fixed conduction time, variable turn off time pulse width modulation (PWM) controller, suitable for low cost power off line flyback switching power supply applications. This device supports the frequency of the anti - go, but also has the characteristics of latch input, natural frequency jitter, negative electricity and the expansion of the power supply voltage range. Figure 4 shows a NCP1351 based 8 W-25 W LED lighting scheme with a 90 to 264 Vac input condition. Figure 4: schematic diagram of W 8 W AC-DC LED lighting applications based on NCP1351.

PFC W-25 W AC-DC to 8 LED lighting applications, it is assumed that the input voltage specifications for 90 to 264 Vac, the power factor is higher than 0.9, the energy efficiency of 80%, providing short circuit and overcurrent protection, output current also has 350 mA, 700 mA and 1 A different choice. In this kind of application, A Morimi semiconductor