Choose the right LED driver power solution for general lighting of different power LEDs

In recent years, the market for high-brightness light-emitting diodes (HB-LEDs) has grown rapidly. LED light efficiency continues to increase, and the cost per even of clear light output continues to decline, making its application range wider, in addition to applications such as portable device backlights with less than 4 inches of screen size and large display screens in sports venues. Infiltrating into the market of automobiles, medium and large size liquid crystal display (LCD) backlights and general lighting, the development prospect is very impressive.

Take the general lighting market such as light bulbs and fluorescent tubes, recessed lights, street lights and parking lights, work lights (table lamps, cabinet lighting), landscape lighting, billboard text circuits, building lighting, etc., it is estimated that current LED lighting The proportion of applications (or solid-state lighting, referred to as SSL) is less than 1%. In 2008, the market size (SAM) of LED drivers and related discrete devices was only about 688 million US dollars. It is expected that the market size will increase to 1.308 billion in 2012. The US dollar has a compound annual growth rate of 17.4%. Therefore, LED general lighting has become a hot market.

This article aims to explore the different power ranges and different power supply applications of the LED general lighting market, as well as the applicable LED drivers and related components, to help lighting design engineers choose the right component solutions to speed up the listing process.

Common power application requirements and solutions for different power AC/DC power supply LEDs

Power supply topologies for different power AC-DC LED lighting applications vary. For applications with power below 80W, the flyback topology is the standard choice; in energy-efficient applications, the resonant half-bridge dual inductor plus single capacitor (HB LLC) is preferred. ON Semiconductor offers AC/DC LED lighting solutions covering a wide power range. Table 1 lists several typical ON Semiconductor AC/DC LED lighting solutions.

Table 1: Typical AC/DC LED General Lighting Solutions from ON Semiconductor

From the power rating of the application, AC/DC powered LED general lighting applications include different types of low power, medium power and high power. Low power applications typically range from 1 to 12W, medium power ranges from 8 to 40W, and high power applications often exceed 40W.

1) 1W to 8W LED general lighting application requirements and solutions

Typical applications for low-power LED general illumination from 1W to 8W, such as G13, GU10, PAR16, PAR20 and recessed lights. The input voltage range for this type of application is between 90 and 264V AC. The constant current output current includes 350mA and 700mA. The energy efficiency requirement is 80%, and protection features such as short circuit protection and overvoltage protection are required.

In this type of application, ON Semiconductor's NCP1015 self-powered monolithic switch control IC can be used. The device integrates a fixed frequency (65/100/130kHz) current mode controller and a 700V high voltage MOSFET to provide all the features needed to build a robust, low cost power supply such as soft start, frequency jitter, short circuit protection, skip cycle, maximum Peak current set point and dynamic self-powering function (no auxiliary winding required).

It is worth mentioning that the NCP1015 can be used in both 1W and 8W LED lighting applications for both isolated and non-isolated solutions to meet different application needs of customers. The cost of these two programs is almost the same. However, the isolated solution uses a transformer to achieve electrical isolation. The solution includes a simple feedback circuit and a clamp circuit for load open circuit and fault protection. It has high safety and is more suitable for applications requiring safety certification. The non-isolated solution uses a tapped inductor to isolate the AC signal, improving the duty cycle of the MOSFET operation and improving system efficiency and circuit performance.

Figure 1: 1 to 8W isolated (a) and non-isolated (b) LED lighting solutions based on ON Semiconductor NCP1015

The above NCP1015-based isolated and non-isolated solutions do not contain PFC, but ON Semiconductor also offers PFC-enabled NCP1015/NCP1014 solutions to provide customers with more choices.

2) 8W to 25W LED general lighting application requirements and solutions: no PFC and PFC

In 8 to 25W AC/DC LED lighting applications, we have to consider two situations. One is that the application does not require power factor correction (PFC). On the other hand, the US Department of Energy (DOE) Energy Star Solid State Lighting (SSL) specification requires mandatory power factor correction (PFC) for any power class. This standard applies to a range of specific products, such as recessed lights, cabinet lights and desk lamps, where the LED driver power factor for residential applications must be greater than 0.7, and for trade applications greater than 0.9. But this standard is a voluntary standard and you can choose not to comply or comply. Therefore, another situation to consider is the requirement for PFC.

Typical applications such as PAR30, PAR38 and recessed lights are not required for PFC's 8W to 25W AC/DC LED lighting. In this type of application, the input voltage requirement is 85~135 Vac or 185~264Vac (or universal input), the energy efficiency requirement is greater than 80%, and the protection characteristics such as short circuit protection and open circuit protection are provided. The constant current output current is 350mA, 700mA. And 1A and other different currents. Accordingly, an NCP1028 or NCP1351 from ON Semiconductor can be used, see Figure 2.

Figure 2: 8-15/25W AC/DC LED lighting scheme based on NCP1028 and NCP1351 (no PFC).

Among them, NCP1028 is an enhanced single-chip switch control IC that provides 800mA peak current. It also provides over-power protection, built-in slope compensation and input undervoltage protection. It is suitable for applications in general wide power input applications. Watt to 15W output power. In addition to the NCP1028-based PFC-free solution, ON Semiconductor now offers a PFC-based solution based on the NCP1028. The NCP1351 is a fixed on-time, variable closed-time pulse width modulation (PWM) controller for low-power off-line flyback switching power applications where cost is critical. The device supports frequency reversal and features latch-in inputs, natural frequency jitter, negative current sensing, and extended supply voltage range.

Typical applications for 8W to 25W AC/DC LED lighting requiring PFC are PAR30, PAR38 and recessed lights. This type of application has an input voltage specification of 90 to 264Vac, 80% energy efficiency, 350mA, 700mA and 1A constant current output, short circuit and overvoltage protection, and power factor requirements above 0.9. This type of application is suitable for ON Semiconductor's NCL30000 single-segment power factor correction LED driver. The single-stage topology saves the dedicated PFC boost section, reducing the number of components and helping to reduce the total cost of the system. The NCL30000 provides a power factor greater than 0.9 to meet IEC Class C harmonic content requirements. The device is capable of directly driving LEDs with precise constant current output control, with energy efficiency greater than 80% at 5 to 15W lower output power, typical energy efficiency above 83%, and supports existing dimming solutions such as TRIAC.

Figure 3: 8-25 W AC/DC LED lighting scheme based on NCL30000 (with PFC).

3) 50W to 200W LED general lighting application requirements and solutions

AC/DC LED applications with power ratings greater than 50W are widely used in street lighting and high-power area lighting, and can be used in different LED schemes for power ranges from 50 to 150W or 100W to 200W. Assume that its input voltage specification is 90--264 Vac, power factor is higher than 0.9, energy efficiency is greater than 85%, short-circuit and over-voltage protection are provided, and constant current output of 350mA, 700mA and 1A is provided. Such applications can be adapted to different needs using the different options described below:

NCL30001: Single-stage PFC LED driver;

NCP1607+NCP1377: CrM PFC+ QR PWM;

NCP1607+NCP1397 or NCP1392/3: CrM PFC+ LLC PWM.

Figure 4: 40-150 W AC/DC LED lighting solution based on NCL30001

Take the NCL30001 as an example. This is a current continuous mode (CCM) controller for single-segment power factor corrected LED drivers in the 40W to 150W power range. The device supports an adjustable switching frequency of 20 to 250 kHz, supports frequency jitter and voltage feedforward, includes input undervoltage and overload timers, provides high energy efficiency and high power factor and robust protection. Figure 4 is typical of the NCL30001. Application circuit diagram.

It is worth mentioning that in recent years, the industry has been eager to have an ultra-high-efficiency LED lighting topology, which is expected to provide more than 90% energy efficiency at relatively low power levels (<50 W). It is higher than the energy efficiency requirement of the external energy source of Energy Star 2.0 (the energy efficiency is higher than 87% when the power is not more than 49W). To achieve such high energy efficiency, a new topology, such as a flyback topology to a resonant half-bridge topology, is required to take advantage of the zero voltage switching (ZVS). Advantageously, ON Semiconductor has already begun to develop energy-efficient half-bridge solutions for LED driver power supplies, such as the NCP1396 and its upgraded NCP1397 high-performance resonant mode controller. The NCP1397 has built-in high-end and low-side drivers that support adjustable and precise minimum frequencies, provide extreme energy efficiency, and offer a variety of fault protection features.

Different power DC/DC power supply LED general lighting application requirements and solutions

For DC-to-DC (DC/DC) powered LED lighting applications, discussions can also be made based on different power ranges.

4) 1~3W DC/DC LED step-down application

Typical 1 to 3W DC/DC LED step-down lighting applications include MR11/MR16, automotive lighting, solar power, and more. This type of application has an input voltage of 5 to 28 Vdc, supports 350mA and 700mA constant current output, frequency up to 500kHz to 2MHz, energy efficiency of not less than 90%, and operating temperature range of -40°C to 125°C. In this type of application, ON Semiconductor's CAT4201 step-down LED driver can be used. The device's patented switch-control architecture drives up to seven LEDs in series (at 24V input) with up to 94% efficiency and provides protection features such as LED open-circuit protection, current limiting and thermal protection.

Figure 5: CAT4201 1~3W DC/DC LED Solution

5) 1~30W DC/DC LED step-down application

Typical 1 to 30W DC/DC LED step-down applications include MR16 spotlights, secondary side DC/DC LED drivers in street lighting. In this type of application, the input voltage range is 7 to 120 Vdc, the output voltage range is 6 to 110 Vdc, and the 350mA, 700mA or 1A constant current output is supported, and the energy efficiency is not less than 90%. This type of application can use ON Semiconductor's NCL30100 buck LED driver. This device's external switching MOSFET provides flexible input voltage and output current design with energy efficiency greater than 95%. See Figure 6(a) for its application circuit diagram.

Figure 6: NHL30010 based 1-30W LED buck application and NCP3066 based 3-20W LED boost application.

6) 1 ~ 20W DC / DC LED boost application

Typical 3 to 20W DC/DC LED boost applications are common in DC/DC LED drivers. This type of application has an input voltage of 5 to 28 Vdc and supports a 350 mA or 700 mA constant current output with an energy efficiency of not less than 90%. This type of application can use ON Semiconductor's NCP3065/NCP3066 LED driver. The NCP3065/NCP3066 can be configured in different modes such as buck, boost, single-ended low-inductance converter (SEPIC) and inverter, and is available in the automotive version, NCV3065/NCV3066. Figure 6(b) shows the application circuit diagram of the boost configuration LED for the NCP3066.

7) 1~3W flashlight LED boost/buck application

1~3W flashlight LED applications include both boost and buck. The boost application has an input voltage range of 1 to 2.5 Vdc and an operating frequency of 1.2 MHz. The buck application has an input voltage range of 4 to 5.5 Vdc and a frequency of 1.7 MHz. Both types of applications need to support 350mA or 600mA constant current output, and the energy efficiency is higher than 90%. In the 1-3 W flashlight boost LED application, ON Semiconductor's NCP1421 step-up DC/DC converter can be used. The same power range of flashlight step-down LED applications can use ON Semiconductor's NCP1529 low-voltage buck converter, application circuit diagrams As shown in Figure 7(a) and Figure 7(b).

Figure 7: NCP1421-based boost and NCP1529-based step-down 1-3W flashlight LED applications

Linear constant current regulator for low current LED lighting applications

According to different power supply types, the requirements of LED applications in different power ranges and the suitable drive power solutions are discussed. But looking at different LED lighting applications, one type of application can be found that focuses on low-current applications, such as trade and industrial signage, car parking lights and taillights, and building and decorative lighting. Common drive solutions for such low current LED applications include low dropout linear regulators and resistors. Both of these drive solutions have their strengths and weaknesses.

Advantageously, ON Semiconductor uses a patent-pending self-biased transistor (SBT) technology, combined with its superior process control capabilities, to introduce a new low-current LED driver solution – NSI45 series double-ended and three-terminal linear Constant current stabilizer (CCR). This solution is simpler than the linear regulator, and the cost is lower, but the performance is greatly improved compared to the resistor scheme, filling the gap in the market. The NSI45 series offers a number of advantages, such as maintaining constant brightness over a wide voltage range, protecting the LED from overdrive when the input voltage is high, and making the LED brighter when the input voltage is low, helping to reduce or eliminate LED code inventory. And to help reduce the total cost of the system, etc., very suitable for low current LED current applications.

Other products and solutions in LED lighting applications

As we all know, LED lighting systems are more complex, involving different fields such as optics, electricity and heat. As the premier supplier of high-performance, energy-efficient silicon solutions for green electronics, ON Semiconductor offers complete LED lighting solutions that include communications, optical sensors, MOSFETs, rectifiers, protection, and filters in addition to drive power. And heat management products, see Figure 8.

Figure 8: ON Semiconductor offers complete optoelectronic portfolio solutions for LED lighting applications

For example, LED ambient light and streetlight intensity control, LED backlight intensity control, and display white balance control applications require very low-energy ambient light sensors and require optical sensors to support accurate low-light levels, especially in the presence of filters. in the case of. In this type of application, ON Semiconductor offers a portfolio of optoelectronic products including optical sensors, LED drivers and high-speed I2C interfaces, including NOA1211 (analog output), NOA1302 (digital output) and NOA1305 (digital output). These photosensors have extremely low operating currents of only 58μA, 550μA and 115μA at 100 lumens of light output.

In addition, LED street lights and other applications in order to reduce the cost of post-maintenance, can add protection devices in the application, such as the use of ON Semiconductor's NUD4700, provide bypass current in the event of an LED open circuit fault, to ensure that other LEDs work properly, and properly handle heat dissipation It can also support more than 1A current. In addition, under the trend of smart grid, engineers can also use ON Semiconductor's AMIS-30585 and AMIS-49587 power line carrier (PLC) modems and NCS5650 PLC line drivers in LED networked streetlight applications. In addition, ON Semiconductor's BC858CDXV6T1G Bipolar Junction Transistor (BJT) can also be used for low-energy constant influenza measurements in LED lighting applications.

Summary of this article

With the emergence of cost-effective, ultra-high-brightness LEDs, solid-state lighting has developed rapidly in recent years. Accordingly, lighting design engineers need to choose different LED driver power solutions based on power supply, luminaires, power range, and LED configuration. From a system perspective, ON Semiconductor offers high reliability products that take into account a variety of factors including electricity, heat and light, including a wide range of AC/DC and DC/DC powered energy efficient LED drive solutions, as well as optical sensors, filtering, protection and Products such as networking provide customers with complete LED lighting solutions.

As the world's leading supplier of high-performance, energy-efficient silicon solutions, ON Semiconductor offers LED lighting drivers and PFC solutions ranging from 1 to hundreds of watts, regardless of the AC/DC power supply used in LED lighting applications. The battery used in DC/DC power supply or LED flashlight, and meet the different requirements of customers for low cost, high cost performance, high energy efficiency or whether to choose to increase PFC.