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However, there's an increasing number of LED lighting products which implement a non-isolated topology for the purpose of cutting cost. The power factor of an LED lamp or luminaire has become a specification requirement in many markets. Power supply specs should include a safe operating temperature range. CCR and PWM can be combined to provide hybrid dimming so the advantages of both techniques can be harvested. DALI is typically used where the control strategy requires the light fixture to respond to more than one controller (e.g., a manual control switch and an occupancy sensor). It is generally preferred to provide a constant voltage supply to multiple LED modules or fixtures connected in parallel. The output voltage of some constant current drivers, especially switching boost converters, can rise too much above the nominal drive voltage due to load disconnection or excessive load resistance. Despite the simplicity in circuit design, additional circuitry is required to effectively reduce the temporal variation in the power supply. Operating a power supply in a CC mode usually requires overvoltage protection just in case an excessive load resistance is encountered or when the load is disconnected. Each LED power supply will also have an ingress-protection (IP) rating. This is likely to cause incompatibility between controls and devices from different manufacturers. The failure of a single LED usually has minimal impact on the total light output. outdoor lighting), some manufacturers are attempting to incorporate this low cost LED driving solution in the visually demanding, safety sensitive indoor lighting applications without improving the drivers output quality (flicker control) and enhancing the electrical safety and heat dissipation of the lighting system. Flicker-free lighting is not only critical for visual tasks that demand precise positioning of the eyes and environments where susceptible populations spend considerable time, it's high desired for HDTV broadcasting, digital photography and slow-motion recording in studios, stadiums and gymnasiums. Any LED driver connected to AC mains supply has to meet the radiated emissions standards such as defined in IEC 61000-6-3. Flyback swiching circuits can be designed for a very wide range of supply and output voltages, with isolation from dangerously high voltages. LED power supplies fall into two broad categories: switched mode power supply (SMPS) and linear power supply. Simply multiplying these will show that our system wattage should be right around 48 Watts. The design of an LED driver involves many compromises. 5. These power supplies work by varying the power on the AC side of the circuit via a TRIAC dimmer. Buck-boost converters can provide an output higher or lower than the input voltage, making them ideal for applications where the input voltage rises and falls with a large variation (no more than 20%). In an LED driving circuit, MOSFET switching is usually the main source of EMI. An important factor that cannot be overlooked when choosing your power supply is the area and environment that it will be used in. Power factor is the ratio of power utilized to power delivered and is expressed as a number between 0 and 1. A more preferred method of open circuit protection is to utilize an active voltage feedback scheme to shut down the supply when the overvoltage trip point is reached. The buck topology is designed for mains-powered LED drivers which are required to drive a long string of LEDs, with the load voltage kept under the supply voltage. A metal oxide varistor (MOV) or transient voltage suppressor (TVS) can be placed across the input to absorb energy by clamping the voltage. The intended use of artificial lighting plays a role. Make sure you know whether you have low-line AC power (90-120VAC) or high-line AC power (200-240VAC). Since their power is limited, Class 2 power supplies cannot power as many LEDs as others outside the rating. An SMPS driving circuit uses a large number of components including filters, rectifiers, power factor corrector (PFC) circuits, etc. One of the major challenges in driver design is to filter out ripples and harmonics without using bulky, short-lived high voltage electrolytic capacitor on primary side. If it is outside the application, it should have a way to mount close by. Architectural Recessed LED Downlights for Hotels, Offices, Museum Shenzhen Ansen Lighting Technology Co., Ltd. HiCloud High Performance UFO LED High Bay Lights, LED Post Top Light Fixtures | Outdoor Post Lights. TRIAC dimmers can be found in common hardware stores. When the switch is off, the diode is forward-biased and magnetic energy is released by current flowing out of the secondary winding. Lighting technology is advancing, light quality is deteriorating. Power supplies operate the most efficiently if they are used within their temperature parameters. Lighting Manufacturers: Thrive In or Ruin the LED Lighting Industry? Flicker is amplitude modulation of the light output that can be induced by voltage fluctuations in AC mains, residual ripples in the output current provided to the LED load, or incompatible interaction between the dimming circuits and LED power supplies. Say for example we have 4 runs of LED strips that run at about 12 watts each. Switched-mode power supplies operate by modulating an electrical signal using one or more switching elements such as power MOSFETs at a high frequency thereby generating the predetermined magnitude of DC power under supply voltage or load variations. DTL can also be used as alternative to MTP if the driver TC point and LED module temperature can be correlated. High-speed switching operation can produce electromagnetic interference (EMI) which adversely affects the surrounding circuit elements. c5;T5 :4KFz /3$bZ>QO=^ Fl}# This will allow even the minimal heat produced by the source to build up over time and end up cooking the power source. This post will go through those many factors and help you select the right power supply for your LEDs! First, we should lock down the power we require from our power source. High-speed switching operation causes much noise, thus leading to a relative high level of electromagnetic interference which has to be filtered and screened using additional circuits. Line voltage will change depending where you are in the world. At the heart of lighting control is dimming technology which is an integral functionality of light management systems. A Class 2 power supply is in accordance with limited power levels defined by the National Electric Code (NEC) and fulfills the Standard UL 1310 requirements. This can easily be done by multiplying your total wattage by 1.2 and then finding a power supply rated for that wattage. On the other side, a short circuit at the load of an LED string can significant affect the total light output. Clearance, which is defined as the shortest distance between two conductive parts, must be factored in to prevent arcing between electrodes caused by the ionization of air. In addition to utilizing components that are rated for high temperatures, the driver has to be designed to pull heat away from thermally-sensitive components. DOB is a typical implementation of the linear driving topology. A boost converter is designed to step up the input voltage to a higher output voltage by about 20% or more. The issues of creepage and clearance distances must be considered for AC powered products. An LED Driver is an electronic device which regulates the power to an LED or a string (or strings) of LEDs. There are plenty of options to choose from so take your time and select the one that fits best in your situation and has the safety requirement from the area surrounding it so that it is set to last a long time. Class 2 power supplies are limited to 60VDC and 100 Watts. So you need some type of constant voltage power supply that can convert your AC household voltage down to a safe DC voltage. You will either need a constant current LED driver or a constant voltage power supply (or a combination of both) in order to make your LEDs work properly. The risk of electric shock is a serious concern in LED products driven by low cost linear regulators. Our technical support team is available 8 a.m. to 5 p.m. EST Monday-Friday. The current limiters typically have thermal shutdown to protect the circuit when a voltage higher than the maximum allowable voltage is placed across the current limiter. Hopefully this post has been helpful in aiding you to find the right power supply for your LED lights. Everything You Need Understanding LED Drivers and How To Choose 7 Things to Know Before Buying and Installing 12V LED Strip Lights. Thermal management is essential for LED luminaires because high junction temperature negatively affects LED performance and reliability. Input voltage fluctuations of this type usually occur in battery-powered lighting applications, e.g., vehicle-mounted lighting for construction and agricultural machinery (forklifts, tractors, harvesters, diggers, snow ploughs, etc.) The potential of this revolutionary lighting technology can only be unlocked when the performance metrics of LED drivers are consistently matched to the electrical characteristics of the LED light source. An input of the AC signal will cause an LED to only light up approximately half of the time when the AC signal is the correct polarity and immediately go out under negative bias. The first number refers to the size of solids that the unit can withstand, whereas the second number refers to the amount of liquid the unit can withstand. The largest disadvantage of SMPS drivers, which is also the most attractive feature of linear drivers, is their reliability. All Rights Reserved. Linear drivers available on the market are dominantly low cost circuits which give no special consideration on flicker elimination. If you wanted to install this in your car, you wouldnt need any power supply. For instance, a 12V power supply would be used with our LED flex strips as that is what they require. Therefore the temperature at which an LED driver is running is fundamentally important in defining its lifetime. High THD can cause issues within the power distribution equipment. Total harmonic distortion (THD) is often brought up in the same breath with the issue of a low PF. It is generally a bad idea to stick a power supply in a tiny enclosure with no ventilation system. Electrolytic capacitors are known for their high-capacitance value and high-voltage rating. Using a right color temperature helps create at OLED lighting offers truly unique forms and design flexibility which are highly appealing for lighting designers, manufacturers and consumers. However, the load voltage of a buck circuit must be less than 85% of the supply voltage. Safety should always remain the number one priority when evaluating a driver and the lighting system it operates. Our current products that offer dimming controls like this are the Magnitude Dimmable Power Supplies. LEDs are solid state semiconductor devices impregnated, or doped, with layers to create a p-n junction. All electrically-conductive and touchable parts of a line-powered Protection Class I LED driver must be connected to earth. The failure detection mechanism of short circuit protection can be implemented by monitoring the duty cycle. The SEPIC converter is characterized by the use of two inductors, preferably a dual-winding inductor which has a small footprint, low leakage inductance, and the ability to increases the coupling of the windings for improved circuit efficiency. On the other side, linear drivers do hold a great potential owing to the previously mentioned advantages. U\D[\M-aDDD;lZ=N* ZSjQ*#cc}wp[=P6cN%u'o[Y5Y7VC+b>f:^%9W/uO.,3e}nNVWtj5x'dSqPp]tg LED drivers designed to operate LED lighting systems for residential and commercial applications are typically listed as Class II. Among the input power 11W is the power loss that escapes in the form of heat. A line-powered LED driver with dielectric isolation, e.g., 1500 V RMS (50 or 60 Hz), from input to output is highly desired. PWM controls the brightness of an LED by varying the duty cycle of a constant current at a pulse rate high enough to be imperceptible to the human eye. In some applications such as street lighting, additional surge protection devices capable of surviving multiple surges or strikes should be added to the driver to protect downstream components from high surges. While linear LED drivers have been envisioned to be a prospective LED driving solution, SMPS is, for the foreseeable future, still the preferred LED driving solution for applications where efficiency, lighting control, light quality, and electrical safety are of paramount concern. The key to mitigating flicker lies in the LED driver which is designed to rectify commercial AC power into DC power and filter out any undesirable current ripple. Does LED Lighting Pose Health RisksBlue Light Hazard, Circadian Disrupt How Do LED Lights Work? The dimming performance of an LED driver is increasingly important as lighting becomes more connected and adaptive to user needs and preferences. Being the only component that characteristically influences the photometric performance and light quality of the LEDs in a lighting system, drivers play a critical role in more extensive and intensive applications of LED technology. And the capacitor eventually fails when electrolyte dries out, leading to the premature failure of the entire lighting system. The change in voltage can be balanced out using a self-adjusting current sharing circuit which still distributes the current equally. The current delivered to an LED string is thus maintained as long as the forward voltage does not exceed the dropout-limited output voltage. As the PF decreases, more power is wasted in the form of reactive power. All Rights Reserved. Linear drivers provides only step-down conversion, which means the load voltage must be kept lower than the supply voltage. Take a look at the helpful chart below and make sure you have a power supply with an IP rating that will protect your source from the environment it will be in. Most CC drivers can be programmed to operate over an output current range for precise pairing between the driver and a specific LED module. Driver maintenance should be taken into consideration when designing a luminaire housing. An LED driver is configured to convert the AC line voltage into DC output as efficiently as possible, and any energy lost in the conversion process will be converted into heat. If you are powering from a battery or happen to have a constant DC voltage that is adequate for your lights, then consider yourself lucky. One of the advantages to LEDs is the ability to respond instantaneously to changes in power input which is regulated by the LED driver. Magnetic energy is stored in the transformer while switch is on and at the same time the diode is reverse-biased (i.e., blocked). An SMPS LED driver uses a switching regulator to transform the unregulated DC current into a pulsed waveform. The color rendering characteristics of a light source include color fidelity, color discrimination, and color preference. VX( Qv#_(|H $)! Constant current power supplies include the switching and linear types. Flicker index is a metric that characterizes the intensity variation over the entire periodic waveform (or duty cycle, for square waveforms). These drivers typically come with IP65, IP66 or IP67 level ingress protection. These types of products will typically call for a constant DC voltage. '(=L&qu*oG^$!b-90r-SQi6Gp(8.V With the ability to generate a substantially resistive dimmer load which is similar to an incandescent lamp, linear LED drivers have generic compatibility with legacy phase-cut (TRIAC) dimmers that were designed for dimming resistive loads. Also called an AC LED light engine, the DOB LED module accommodates the LEDs and all the driver electronics on a metal-core printed circuited board (MCPCB). LED drivers can be remote mounted or co-located within lamp or luminaire housings. A purely resistive loads has a power factor of 1 because draws current exactly in phase with the line voltage. For LED applications it is a good idea to select a power source with 80% efficiency or higher. IP ratings consist of a two-digit code that indicates the size of solids and pressure of liquids that a power supply can resist. Widespread use of aluminum electrolytic capacitors in the PFC as an energy-storage component introduces the biggest concern about the reliability of an SMPS driver. These additional circuits can tremendously increase the physical sizes and double the overall cost of the LED driver. CV drivers are often used in low voltage LED lighting applications that demand ease of group connection in parallel control, e.g., driving LED strip lights, LED sign modules for lightboxes. Wiring LEDs Correctly: Series & Parallel Circuits Explained! FIRSTMake Sure you have control of the current to your LEDs. TLAs may be less of a concern for roadway, parking lot, and outdoor architectural lighting, or other applications where the duration of exposure to artificial light is limited. Input overvoltage protection (IOVP) is designed to relieve the driving circuit from overvoltage stress as a consequence of switching operations/load change on the power grid, lightning strikes nearby, lightning strikes directly on the lighting system, or electrostatic discharge. HiMast High Power LED Flood Lights for Outdoor Sports Lighting an HiSky LED Industrial High Bay & Suspended Street Lights. The ratio of on time to off time determines the perceived light intensity. While it's acceptable to employ linear drivers in LED luminaires for applications where high quality light and AC mains isolation aren't a top priority (e.g. For this setup I would use a power supply outputting at least 24VDC. A Tricky Technology, A Messy Marketplace, Thermal Management Technologies for LED Lighting Systems. The non-isolated topology provides no electrical isolation from the AC mains supply. The SPD should be rated reduce or discharge high pulse energy of a minimum 10 kV and 10 kA, as per ANSI C136.2. As LEDs are very sensitive to current and voltage fluctuations, one of the most important roles of an LED driver is to reduce variations in forward voltage across the semiconductor junction of the LEDs. [? However, the 0-10V dimming standards for architectural applications in the US do not define the value of the minimum light output and address the shape of the dimming curve. Overtemperature protection for LED systems include Module Temperature Protection (MTP) and Driver Temperature Limit (DTL). An electrical circuit that regulates the incoming power to provide a constant-voltage output has typically been referred to as a power supply, whereas an LED driver in the strict sense refers to an electrical circuit that provides a constant current output. Percent flicker measures the relative change in the light modulation (the depth of modulation). It is best to operate within this and make sure not to stick your power supply somewhere where heat can build up and go above this maximum operating temperature. A linear power supply uses a control element (such as a resistive load) which operates in its linear region to regulate the output. If you wish to put it inside the product you are making, it has to be small enough to fit in the space provided. Percent flicker is better known to general consumers. The transition from traditional lighting technology to solid state lighting is driven by the need for greater efficiency, control and interaction. There are many different factors to consider when choosing a power supply for LED lighting. As the second number increases the product goes from being only protected in light rain to being protected in full immersion. The maximum number of LEDs or LED modules and the forward voltages across them must not exceed the DC electrical energy power supply. In general, 10 percent flicker or less at 120 Hz or 8 percent flicker or less at 100 Hz is tolerable for most people except for the at-risk populations, 4 percent flicker or less at 120 Hz or 3 percent flicker or less at 100 Hz is considered safe for all populations and highly desired in visually intensive applications. Rapid alteration in polarity gives rise to a flicker in the intensity at a frequency twice the AC sinusoidal frequency. Color temperature is closely associated with the synchronization of human circadian rhythms to the 24-hour solar cycle. PWM dimming is challenging with the large output capacitor as well as the closed-loop control which demands a large bandwidth to stabilize the converter. LED Street Lights with Photocells | 30 40 50 200 240 Watts. A linear LED driver can be of low efficiency, when the supply voltage runs substantially higher than the load voltage. Series connection is preferred in CC circuit architectures because it ensures all the LEDs have the same current flowing across their semiconductor junctions and the light output is uniform across the LEDs. The disadvantage of this topology is that it offers no isolation between the input and output circuits. The input/output circuit isolation can only be accomplished with a transformer which has primary and secondary windings with good galvanic isolation. The selection between SMPS and linear drivers has to take cost, efficiency, control, lifespan, dimming, size, power factor, flicker, input/output, AC mains isolation, and various other factors into consideration. Switch-mode converters used in LED drivers require energy to be stored as current using inductors and/or as voltage using capacitors so as to maintain the output current or voltage on the load during the on/off switching cycle. The conversion from current to light output is nearly linear, increasing the input current allows more electrons and holes recombining in the p-n junction and thus more photons are generated. The limitation of having to keep the load voltage lower than the supply voltage within a certain range leads to a further disadvantage of only allowing a restricted supply voltage range. Digital modulation allows encoding the data in binary for high-speed optical wireless communication (LiFi), which vastly expands the application potential of SMPS drivers. This eliminates entirely the need for a dedicated driver assembly and thus allows for a compact form factor. The 12V supply from the battery would be totally adequate for your lights. LED drivers usually come with a limited level of surge protection from the built-in overvoltage protection circuits. Therefore, it is necessary to have PF and THD measured at full and dimmed outputs. So make sure the area isnt too warm or cold and that the heat cannot build up to damaging levels. High temperature will accelerate electrolyte evaporation, which causes a decrease in capacitance and an increase in ESR (equivalent series resistance). Distorted current waveforms can reduce the PF and create harmonic distortion as well. Cars batteries give off 12VDC give or take. When the driver is co-located within the luminaire housing, the thermal load from the LEDs will end up in additional increase in the driver temperature. However, these circuits are less efficient (75 - 85%, higher efficiency is possible by using expensive parts). However, linear drivers are struggling with their inherent disadvantages that hold them back from entering mainstream applications in quite a few product categories. Power supply specifications should list whether a power source is dimmable or not and what dimmer control type it uses. An LED lighting system is a synergistic combination of the light source, LED drivers, thermal management systems, and optics. Constant voltage drivers can only be PWM dimmed. This technology is currently being abusively used. You must look to make sure a power supply qualifies for alternating current (TRIAC) dimming by checking the specs. If you are building your own LED fixture or working with any of our component star LEDs, you will need a constant current device within your system. As each number increases, so does the level of protection. But in order to incorporate these strips in homes there is the need for an AC to DC converter that will take the 120VAC standard household voltage and convert it down to 12VDC. For the switched-mode power conversion in LED drivers, various circuit topologies are available to support the LED load requirements. This poses an additional design challenge to overcome. However, the LED driver must be designed to recognize and respond to the voltage signals from the dimming circuit. There's no enclosure grounding for class II LED drivers, but all the conductor inside a class II drivers must be dual or reinforced insulated to ensure good insulation between the mains power circuit and the output side or the metal casing of the driver. The presence of these harmonic distortion and nonlinear loads can lead to various problems such as overheating of neutral conductors and distribution transformers, failure or malfunction of the power generation and distribution equipment, and interference with communication circuits, etc. How do lighting manufacturers differentiate themselves and thrive i Human centric lighting (HCL) synchronizes human biological clocks to the natural dynamics of a solar day. The control circuit sends low voltage control signals to adjust an input to the driver by varying the voltage between 1V and 10V DC. Each LED runs at about 3.1 volts. This places a high thermal stress on the LED driver circuit. It provides power conversion, load regulation, and downstream component protection.