As the sizes of electronic circuits continue to shrink, a good PCB design is essential for a driver circuit to not only reduce EMI emissions, but also reduces creepage and clearance problems. It is the conjunction of wireless networking and automatic lighting con Tunable white lighting visually, biologically and emotionally contributes to human interaction with the physical world. Open circuit protection or output overvoltage protection (OOVP) provides a shutdown mechanism which uses a Zener diode to give feedback and conduct the output current to ground when the output voltage exceeds a certain limit. Electromagnetic compatibility (EMC) is the ability of a device or system to operate in its electromagnetic environment without yielding EMI that disturbs neighboring equipment or being disturbed by the EMI radiated by neighboring equipment. Therefore utility companies have regulatory requirements on the power factor (PF) and total harmonic distortion (THD) of electrical equipment, including line-powered LED luminaires. This is because PWM dimmers go in-line with the strip lights, dimming on the 12VDC side of the circuit. The 12V supply from the battery would be totally adequate for your lights. This will allow even the minimal heat produced by the source to build up over time and end up cooking the power source. The SPD should be rated reduce or discharge high pulse energy of a minimum 10 kV and 10 kA, as per ANSI C136.2. For this setup I would use a power supply outputting at least 24VDC. For instance, a 12V power supply would be used with our LED flex strips as that is what they require. All Rights Reserved. However, in a switching buck regulator, a short circuit will lead to a failure of an LED or the entire module depending on the circuit design. An LED driver circuit should have immunity against voltage spikes and other noise on the AC line within a predetermined design range while also filtering out harmonics in the output current to prevent them from affecting the output quality of the LED light source. When selecting a power supply for your LED project it is important to know where it needs to fit or be installed. Therefore the temperature at which an LED driver is running is fundamentally important in defining its lifetime. Note that you should always make sure the low voltage driver in use (Mean Well LDD-H in this case) is rated for the voltage you want to input. 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. A lot of power supplies, such as Mean Well products, will be rated for the full range but it is always helpful to know your AC input and make sure that the power supply you use is suited for this. In the commercial and industrial sectors, utilities will often surcharge end-users who operate with low-PF electrical equipment to compensate increased generation and transmission cost. A plastic film capacitor, which is typically connected across the AC line to reduce EMI emissions, also helps absorb some of the energy in surge pulses. 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. 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. When the current flows across the doped layers, holes from the p-region and electrons from the n-region are injected into the p-n junction. Typically, low voltage drivers like the Mean Well LDD-H work better if you have a small cushion over the voltage they require. 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. A 60-Watt (or higher) power supply will suffice for this project. They typically outlive SMPS drivers, simplifies lamp design, and delivers cost, and reduce the BOM significantly. The driver may power a single module with LEDs connected in series or multiple LED modules connected in parallel. Some types of LED drivers have additional electronics to enable precise control of the light output or to support smart lighting. A constant voltage LED driver is used to regulate the output voltage for an LED circuit in which multiple LED modules are connected in parallel. So it's important that LED drivers meet regulatory THD values (typically less than 20%) over the entire input voltage range. The failure detection mechanism of short circuit protection can be implemented by monitoring the duty cycle. Driver maintenance should be taken into consideration when designing a luminaire housing. And the capacitor eventually fails when electrolyte dries out, leading to the premature failure of the entire lighting system. 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. However, these circuits are less efficient (75 - 85%, higher efficiency is possible by using expensive parts). The excess power is released as heat energy, resulting increased thermal stress on the driver circuit and very likely on the LEDs as well if heat is not efficiently dissipated. 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. TRIAC dimmers can be found in common hardware stores. In particular, the digital controllability of SMPS drivers, which are equipped with smart sensor technology and wireless connectivity, promises to enable a variety of Internet of Things (IoT) applications. Breaking Down the LED Grow Light Metrics: A Guide to Dimming LEDs: How to tell if your What is RGB Lighting? The EMC performance of the LED driver is often automatically assured by a good EMI design. Therefore they're one of the key considerations in light quality assessment. 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. Overtemperature protection for LED systems include Module Temperature Protection (MTP) and Driver Temperature Limit (DTL). Class 2 power supplies are limited to 60VDC and 100 Watts. The most commonly used dimmer-to-driver controls include triac (triode for alternating current), 0-10V, and DALI (Digital Addressable Lighting Interface). To get started, find out how many watts your light will consume. The object of thermal manageme Wireless connectivity is an integral part of Internet of Things (IoT) enabled lighting systems. A metal oxide varistor (MOV) or transient voltage suppressor (TVS) can be placed across the input to absorb energy by clamping the voltage. 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. Unlike the SMPS driver circuitry which has to be mounted on a routed FR4 PCB, these surface-mount driver ICs can be soldered to the LED-mounted MCPCB without circuit routing. Make sure you know whether you have low-line AC power (90-120VAC) or high-line AC power (200-240VAC). As such, CCR is the preferred dimming technique for remote-mounted systems. The failure of a single LED usually has minimal impact on the total light output. Check out Mean Well and Phihong power supplies for the most efficient selection as they have efficiency ratings running well into the 90 percentile. The lower the value, the better. Safety should always remain the number one priority when evaluating a driver and the lighting system it operates. Artificial light with a high percentage of flicker should not use for both ambient lighting and task lighting in homes, offices, classrooms, hotels, laboratories and industrial spaces. Most importantly, this reactive power will cause the delivered power (apparent power) larger than the power actually required by the LED luminaire. The creepage distance between primary and secondary circuits must meet the spacing requirements otherwise electrocution or fire can occur. In a SEPIC architecture, the boost section provides power factor correction (PFC) and the buck section produces a voltage to be the same as, lower, or higher than the input voltage, while output polarity of both sections remains the same. A linear power supply uses a control element (such as a resistive load) which operates in its linear region to regulate the output. IP ratings consist of a two-digit code that indicates the size of solids and pressure of liquids that a power supply can resist. Cars batteries give off 12VDC give or take. 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. All electrically-conductive and touchable parts of a line-powered Protection Class I LED driver must be connected to earth. If your LEDs are dimmable and you would like to adjust their brightness, make sure you choose a power supply that has dimming capabilities. 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. 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. Color temperature is closely associated with the synchronization of human circadian rhythms to the 24-hour solar cycle. Does LED Lighting Pose Health RisksBlue Light Hazard, Circadian Disrupt How Do LED Lights Work? 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. This is likely to cause incompatibility between controls and devices from different manufacturers. 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%). Most finished LED products or LED strip lights (that you would buy straight from the store) already have drivers or resistors built in to regulate the current. CCR and PWM can be combined to provide hybrid dimming so the advantages of both techniques can be harvested. Hopefully this post has been helpful in aiding you to find the right power supply for your LED lights. Self-contained LED drivers for wet locations are usually potted in silicone to enhance enclosure integrity while also facilitating electrical insulation and thermal management. Low-power boost converters can use a charge pump, rather than an inductor, which uses capacitors and switches to raise the output voltage above the supply voltage. PWM dimming is commonly used for both static and dynamic intensity adjustment with white light sources as well as RGB LEDs. Among the input power 11W is the power loss that escapes in the form of heat. In AC line applications, slight but sustained overvoltage can cause high currents (energy impulses) in the LED driver and LEDs, which may lead to failure of the LED driver and control interfaces, and the premature aging of the LEDs. In remote-mounted systems, PWM drivers can experience performance losses over a long distance. 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. With six of these our total voltage in this series circuit would be 18.6VDC. LED products with built in current regulators will usually be pretty good about specifying what input voltage should be used. 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). 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 importance of LED dimming is beyond what most people would ever imagine. The largest disadvantage of SMPS drivers, which is also the most attractive feature of linear drivers, is their reliability. All Rights Reserved. Boost circuits generally require one inductor and operates in either the continuous conduction mode (CCM) or discontinuous conduction mode (DCM), as determined by the waveform of the inductor current. The Mean Well LDD-H can take 9-56VDC so we are all set in this situation. AC LED lights, in particular, come with flicker typically higher than 30 percent at 120 Hz. The stroboscopic effect and phantom array will typically occur within a frequency range of between 80 Hz and 2 kHz, their visibility varies in populations. The change in voltage can be balanced out using a self-adjusting current sharing circuit which still distributes the current equally. Class II drivers are popular as they do not require a ground connection. The current delivered to an LED string is thus maintained as long as the forward voltage does not exceed the dropout-limited output voltage. 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. 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. This eliminates entirely the need for a dedicated driver assembly and thus allows for a compact form factor. An AC-DC SMPS LED driver rectifies AC power into DC power which is then converted into DC power capable of driving the LEDs properly. Standards for limiting flicker for different applications are yet to be established. Rapid alteration in polarity gives rise to a flicker in the intensity at a frequency twice the AC sinusoidal frequency. The efficiency of a power supply tells the amount of power that actually goes toward making the LED light up. In an LED driving circuit, MOSFET switching is usually the main source of EMI. 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. jBqM a+ c=o? qO[IiP=EQ%; PWM dimmers actually pulse the lights at high frequencies to change the perception of light to the naked eye. Switching power supplies are obviously more efficient than the linear ones because of their "0/1" (ON/OFF switching) modulation. Copyright 2019 LEDSupply. LED drivers designed to operate LED lighting systems for residential and commercial applications are typically listed as Class II. If you dont have a current limiting device, finding a driver is your first step; but if your LED product already has current under control, you can follow this post in finding a constant voltage power supply. DALI, with the ability to provide addressing of individual fixtures and status feedback from the loads, provides great flexibility in lighting control through a 4-wire (Hot and Neutral, plus 2 low-voltage data link topology-free wires) system. 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. 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. 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). Percent flicker measures the relative change in the light modulation (the depth of modulation). Electrolytic capacitors are known for their high-capacitance value and high-voltage rating. The way that switching regulators draw pulses of current from the utility power grid can produce kinks and distortions in the power line current waveform as well as trip fuses and circuit breakers at power levels lower than power line capability. A constant voltage power supply can be used to power LED lights that have resistors or constant current drivers already within the system. '(=L&qu*oG^$!b-90r-SQi6Gp(8.V A metal screen may be mounted over the switching area to provide an enclosure that stops EMI radiation. The State of California has clear regulation for PF value which has to be greater than 0.9 for all power levels of residential and commercial LED lighting. Driving multiple LED modules in parallel requires a resistor in each LED module, which leads to lower efficiency and poor current matching. Wiring LEDs Correctly: Series & Parallel Circuits Explained! 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. Make sure to have a large enough power supply by giving yourself a 20% cushion over the total wattage you calculate from your LEDs. If the load voltage is higher than the supply voltage or the supply voltage has a wide variation, a switching regulator is needed. Flicker that occurs at frequencies of 80 Hz and lower is directly visible to the eye, and invisible flicker is the temporal variations occurring at frequencies of 100 Hz or higher. Therefore, LED drivers should incorporate protection mechanisms in order to address these challenges. Whether you are building your own LED fixture, fixing and retrofitting existing fixtures, or purchasing new LED lights, you will need to find the correct power source for your LEDs. CCR or analog dimming adjusts light intensity by changing the DC drive current flowing through an LED. Nonetheless, the captivating features of SMPS drivers are achieved at the expense of their dependence on bulky, expensive and unreliable reactive components, such as transformers, inductors, and capacitors. The transition from traditional lighting technology to solid state lighting is driven by the need for greater efficiency, control and interaction. 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. A flyback switching circuit is a discontinuous conduction mode converter which provides AC mains isolation, energy storage, and voltage scaling. Open up White LEDs are no more hazardous than other lighting technologies that have the same correlated color temperature (CCT). In RGB color mixing applications, PWM dimming allows the brightness of the individual sources to be precisely adjusted to deliver the desired color. Digital modulation allows encoding the data in binary for high-speed optical wireless communication (LiFi), which vastly expands the application potential of SMPS drivers. The input/output circuit isolation can only be accomplished with a transformer which has primary and secondary windings with good galvanic isolation. One of the advantages to LEDs is the ability to respond instantaneously to changes in power input which is regulated by the LED driver. THD is a measurement of distortion in the current waveform caused by non-linear electrical loads such as rectifier loads. It is generally a bad idea to stick a power supply in a tiny enclosure with no ventilation system. 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. The higher the frequency, the brighter they will be. Constant current LED drivers are used when light output should be independent of the input voltage fluctuation. LED drivers usually come with a limited level of surge protection from the built-in overvoltage protection circuits. The buck-boost converter is a non-isolated driver circuit. Phase control dimming is often used in retrofit applications where pulling new or additional branch circuit wiring or back-end control wiring can be complicated and expensive. An SMPS driving circuit uses a large number of components including filters, rectifiers, power factor corrector (PFC) circuits, etc. LED drivers can be remote mounted or co-located within lamp or luminaire housings. Simply multiplying these will show that our system wattage should be right around 48 Watts. The change in power that the dimmer creates on the AC input side will vary the voltage on the DC output and control the brightness of the LEDs. 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. 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.