> Quick answer: At low battery voltages, boost converters excel in solar lamps by stepping up voltage to match LED string requirements, improving system efficiency by nearly 10% [6]. Buck converters work best when input voltage exceeds LED string voltage, while buck-boost topologies adapt to fluctuating voltages, ensuring consistent performance across wide input ranges [4][24].
Solar lamps are increasingly vital in Romania’s rural and off-grid communities, where stable power is scarce. As battery voltages drop during extended cloudy periods or nighttime use, the choice of LED driver topology becomes critical to maintaining brightness and extending runtime. The efficiency of buck, boost, and buck-boost converters under low voltage conditions determines how long a solar lamp can operate before needing recharge or replacement [4].
Buck Converters: Efficient When Input Exceeds LED Voltage
Buck converters step down voltage to match the LED string’s forward voltage, making them ideal when input voltage is higher than the output requirement [4]. They are widely used in automotive lighting systems where voltages range from 6 V to 18 V [10][11][12]. Key efficiency factors include fixed frequency operation, low resistance switches, and spread spectrum frequency modulation to reduce electromagnetic interference (EMI) [10][11][12]. However, buck converters fail at low battery voltages when input drops below the required LED voltage, causing system shutdown [4].
Boost Converters: Optimal for Low Input Voltages
Boost converters, or step-up converters, are essential when input voltage is lower than the total LED string voltage [10][11][12]. This topology is crucial in solar-powered systems where battery voltage can dip below 3 V during extended darkness [15]. SolarOne’s SOLED mc2 system uses a boost converter to eliminate balancing resistors, reducing losses and improving overall efficiency by nearly 10% [6]. This makes boost converters the top choice for solar lamps operating at low battery levels [6].
Buck-Boost Converters: Best for Variable Voltage Conditions
Buck-boost converters deliver output voltage that can be either higher or lower than the input, offering adaptability across wide voltage ranges [4][24]. They dynamically switch modes based on input voltage, maintaining constant current delivery regardless of battery state [19][20]. A dual-mode constant-current driver can operate efficiently over a broad DC input range, maximizing performance in fluctuating solar conditions [19][20]. This versatility makes buck-boost the ideal topology for solar lamps in regions like Romania, where sunlight varies seasonally and daily [24].
Comparison of Driver Topologies in Solar Lamps
| Topology | Best For | Efficiency at Low Voltage | Key Advantage | Limitation |
|–––––|––––––––––––|–––––––––-|––––––––––––|–––––––––––-|
| Buck | High input voltage, stable battery | Moderate (fails at low V) | High efficiency when V_in > V_out | Fails when input drops below LED voltage [4] |
| Boost | Low input voltage, solar systems | High [6] | Steps up voltage; ideal for low battery [15] | Efficiency drops at very high step-up ratios |
| Buck-Boost | Fluctuating inputs (e.g., solar) | Very High [19][20] | Adapts to wide voltage ranges [4] | More complex design, higher cost |
Dimming and Luminous Efficacy at Low Currents
Operating LEDs at reduced drive currents increases luminous efficacy—lumens per watt—by 5 to 20% due to lower junction temperatures [16]. This is especially beneficial in solar lamps, where energy conservation is paramount. Dimming techniques like linear current regulation offer simple control but limited dimming range [24]. Digital dimming provides greater flexibility, enabling deeper brightness adjustments without compromising efficiency [24].
Designing for Romania’s Climate
Romania experiences variable solar input—long, dark winters and short, intense summer days. A solar lamp using a boost or buck-boost driver can maintain performance even when battery voltage drops below 3 V [15]. With Infineon Technologies achieving LED driver efficiencies above 90% [18], modern designs can minimize power loss while maximizing runtime, crucial for off-grid users [18].
Key Takeaways
- Boost converters improve solar lamp efficiency by up to 10% at low battery voltages [6].
- Buck-boost topologies ensure consistent performance across fluctuating solar conditions [19][20].
- Lower drive currents increase LED luminous efficacy by 5–20% [16].
- Buck converters fail when input voltage drops below LED string voltage [4].
- Digital dimming enables deeper, more efficient brightness control [24].
References
- [4] Building_a_Versatile_LED_Driver_-_Electronic_Design__8ec5b025 — magazine
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# Building a Versatile LED Driver Source: Blog/Web URL: https://www.electronicdesign.com/technologies/power/whitepaper/21156071/analog-devices-building-a-versatile-led-driver Author: Victor Khasiev Date: 2021-03-30 This article is part of the Power Management Series: Driving LED Designs What you'll learn: – Different topologies used in developing LED drivers. – Proper connections for buck, boost, and buck-boost configurations. – Test results for the three topologies using the same LED string. Today’s LED drivers are highly flexible, enabling their use in a wide array of applications from scanners to automobiles to avionic lighting. Many of these drivers can also be configured using multiple topologies —boost, buck, and buck-boost—to meet a wide variety of specific application requirements. For low input voltages and high string voltages, a boost topology is appropriate, whereas a buck is more suitable for high input voltages and low string voltages. A buck-boost topology is used for a wide range of inputs where voltage can be below or above the LED string. This article covers the process of selecting the suitable topology and its corresponding connections. For purposes of illustration, the examples are based on the LTM8042 µModule LED driver. This driver supports LEDs with up to 1-A current and a 3000:1 dimming ratio, operates from input voltages of 3 to 30 V, and has a frequency range of 250 kHz to 2 MHz. Boost LED Driver The most common topology for an LED driver is a boost
- [6] The_case_for_solar-powered_LED_lighting_Buildings__1496c42d — authority
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lighting (assuming that the lighting design incorporates multiple LED installations to compensate for shadows in a space measuring 4 feet square). The relatively low lumen output ratings of LED lamps are often times compensated for when looking at the foot-candle levels at the illuminated surfaces. In other words, for outdoor lighting applications, SolarOne estimates that an LED lamp rated at 45 lumens per watt will perform equivalently to a fluorescent bulb rated at 75 lumens per watt. This facet of LEDs offer an enormous side benefit to areas with dark-sky mandates. 2. Optimized system efficiency Solar cells and LEDs share many characteristics – even in the assembly process. For example, both solar cells and LEDs require sorting and balancing to optimize performance. The SOLED mc2 LED Lamp and Lamp Driver is configured to effectively eliminate the need for balancing resistors and their associated losses. Perhaps more significantly, through its range of testing and field experience, SolarOne has identified "sweet spots" in LED operation that optimize current flows and light levels with solar panel and battery costs. The trade-offs are quite different than grid-connected or even automotive applications. This translates into almost a 10% improvement in overall system efficiency. 3. Fine tuned to user needs
- [10] LED_Driver_Topology_Guide_for_Automotive_Applications__f0be1251 — magazine
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diagrams with the controller modulating the high-side switch for current control. Click image to enlarge Table 1. Advantages and Trade-Offs of Using Buck Converters as LED Drivers Several critical features to look for in step-down LED drivers are fixed frequency operation, high efficiency through excellent switching control and low resistance switches, high accuracy throughout the analog dimming range, and, for excellent EMI, a properly designed spread spectrum frequency modulation. Step-Up (Boost) Converters Step-up (or boost) LED drivers regulate the current in an LED string from a voltage that is lower than the total LED string voltage. This is useful in many automotive systems, where many LEDs need to conduct in a single string. Typical 12 V automotive systems have operational ranges from 6 V to 18 V — requiring that the LED driver runs down to 6 V, providing large step-up ratios for the LED store main illuminated. Figure 3 and an example schematic in Figure 2 show basic system diagrams with the controller modulating the low-side switch for current control. Click image to enlarge Figure 2. Boost converter example: LT8356-1 Click image to enlarge Table 2. Advantages and Trade-Offs of Using Boost Converters as LED Drivers Boost-Buck Using a Boost Converter Some step-up (or boost) LED drivers may be configured to return the LED cathode to the supply. This configuration is referred to as buck-boost. The total output voltage is VIN (VBATTERY), which is added to the total LED s
- [11] LED_Driver_Topology_Guide_for_Automotive_Applications__f2ec020d — magazine
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diagrams with the controller modulating the high-side switch for current control. Click image to enlarge Table 1. Advantages and Trade-Offs of Using Buck Converters as LED Drivers Several critical features to look for in step-down LED drivers are fixed frequency operation, high efficiency through excellent switching control and low resistance switches, high accuracy throughout the analog dimming range, and, for excellent EMI, a properly designed spread spectrum frequency modulation. Step-Up (Boost) Converters Step-up (or boost) LED drivers regulate the current in an LED string from a voltage that is lower than the total LED string voltage. This is useful in many automotive systems, where many LEDs need to conduct in a single string. Typical 12 V automotive systems have operational ranges from 6 V to 18 V — requiring that the LED driver runs down to 6 V, providing large step-up ratios for the LED store main illuminated. Figure 3 and an example schematic in Figure 2 show basic system diagrams with the controller modulating the low-side switch for current control. Click image to enlarge Figure 2. Boost converter example: LT8356-1 Click image to enlarge Table 2. Advantages and Trade-Offs of Using Boost Converters as LED Drivers Boost-Buck Using a Boost Converter Some step-up (or boost) LED drivers may be configured to return the LED cathode to the supply. This configuration is referred to as buck-boost. The total output voltage is VIN (VBATTERY), which is added to the total LED s
- [12] LED_Driver_Topology_Guide_for_Automotive_Applications__1a242014 — magazine
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diagrams with the controller modulating the high-side switch for current control. Click image to enlarge Table 1. Advantages and Trade-Offs of Using Buck Converters as LED Drivers Several critical features to look for in step-down LED drivers are fixed frequency operation, high efficiency through excellent switching control and low resistance switches, high accuracy throughout the analog dimming range, and, for excellent EMI, a properly designed spread spectrum frequency modulation. Step-Up (Boost) Converters Step-up (or boost) LED drivers regulate the current in an LED string from a voltage that is lower than the total LED string voltage. This is useful in many automotive systems, where many LEDs need to conduct in a single string. Typical 12 V automotive systems have operational ranges from 6 V to 18 V — requiring that the LED driver runs down to 6 V, providing large step-up ratios for the LED store main illuminated. Figure 3 and an example schematic in Figure 2 show basic system diagrams with the controller modulating the low-side switch for current control. Click image to enlarge Figure 2. Boost converter example: LT8356-1 Click image to enlarge Table 2. Advantages and Trade-Offs of Using Boost Converters as LED Drivers Boost-Buck Using a Boost Converter Some step-up (or boost) LED drivers may be configured to return the LED cathode to the supply. This configuration is referred to as buck-boost. The total output voltage is VIN (VBATTERY), which is added to the total LED s
- [15] Powering_LEDs_from_solar_cells_Electronic_Design__864ed05b — magazine
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these components directly, but doing so involves significant trade-offs in system efficiency and robustness. Now consider adding a simple power electronics interface in the form of a battery charger and LED driver. This gives a much higher degree of flexibility and lets the designer optimize the overall system performance. A standalone battery-charger IC can manage the NiMH charging profile, and an LED driver IC can convert the battery voltage into a constant-current source. There is no real need to add a controller. However, there are at least two down sides to this discreet IC configuration. First, it limits the permissible range of operating conditions. ICs for managing batteries and driving LEDs often have a fairly narrow operating range, which limits the designer’s ability to make changes down the road or in response to customer requests. For instance, use of a new solar-cell configuration may necessitate use of a different battery-charging IC. If the energy-storage technology or configuration changes, it’s likely both the battery-charging IC and the LED-driver IC will have to go. And if there is a change in the type of LEDs or their series/parallel configuration, the LED driver will need to be reconfigured. The inclusion of a microcontroller helps handle these difficulties by providing some flexibility. Reprogramming can take the place of significant hardware changes. The second downside to the use of discrete ICs for these functions is that it makes system optimization
- [16] Does_LED_efficiency_increase_with_lower_drive_currents_Forum__de808ccc — authority
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# Does LED efficiency increase with lower drive currents? Source: Blog/Web URL: https://forum.digikey.com/t/does-led-efficiency-increase-with-lower-drive-currents/6451 Author: Tilopa Date: 2020-05-07 Relative to arrays of strip LED lighting, I’ve heard people say that distributing current across more strips lowers the current for each strip and increases efficiency. Is this right? If so what type of efficiency are we talking about? I’m interested in increasing luminous efficiency, but I fail to see how diluting current by adding more strips increases efficiency. Wouldn’t each strip be just that much lower in luminous flux, and the sum total would be the same? Yes, operating a given emitter at reduced drive current levels typically does yield an increase in luminous efficacy (lumens/watt), because LEDs are not strictly linear in terms of this behavior. Higher per-strip drive levels promote higher operating temperatures, which depending on the scenarios one chooses to compare can cause reductions in efficacy on the order of 5 to 20%. Question about nominal drive current. “Nominal” drive current values typically indicate the level at which the other device characteristics are measured and communicated. Manufacturers generally choose this value to reflect an operating point that offers a good balance of competing design tradeoffs under expected operating conditions. Because different applications value different performance characteristics differently, it’s not necessarily the op
- [18] LED_lighting_system_design_Infineon_Technologies__e956b07e — authority
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# LED lighting system design | Infineon Technologies Source: Blog/Web URL: https://www.infineon.com/applications/industrial/led-lighting-system-designs Author: Date: 2026-06-19 LED lighting system design Broad portfolio of semiconductor solutions for commercial and industrial LED lighting applications and systems – On this page Browse by category About We at Infineon have been focusing on LED drivers and connected and smart Lighting for many years. With our products and solutions, we are supporting high light and power quality in LED drivers as well as high efficiency of significantly above 90%. In the first step, the focus of the market has been on energy savings by just replacing incumbent light sources with LEDs. But due to further increase in energy cost and pressure on carbon footprint reduction, the efficiency of the LED drivers and the usage of presence detectors based on reliable radar technology are becoming more mainstream. Whatever your need, Infineon has you covered with our portfolio of LED driver ICs that support a platform approach for LED drivers in commercial and industrial lighting as well as indoor and outdoor LED lighting. A comprehensive portfolio of high-voltage MOSFETs and low-voltage MOSFETs, benchmark for linear- and switch-mode LED driver ICs, microcontrollers with dedicated peripherals for smart lighting system design and solutions, with high-efficiency power conversion, and dimming technologies as well as easy-to-use wireless communication and sens
- [19] US9992826B1_-_Dual_mode_constant_current_LED_driver__71bc120a — patent
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unit. When one more LED is turned on, the current drops until the controller reacts and pushes the current up again. And when an LED is turned off (the corresponding switch being turned on) the current suddenly goes up until the feedback reduces it back to the desired level. – the battery voltage available for headlights can vary greatly, for example for a nominal 12V battery system, the headlights operates with no derating for the DC voltages from 8 to 24 volts and with derating down to 6 or up to 28 volts. There is a need for LED based automotive headlights with many individually-dimmable LEDs fed by compact and reliable derivers. – the LED driver of the present disclosure includes a converter topology, and a mode selection circuit that control the mode of the circuit based on the voltage to maximize efficiency of the LED driver. – the converter topology and mode selection circuit operate in a first buck-boost mode when the output voltage of the LED driver is less than the voltage of the DC power source plus a first threshold amount. – the converter topology and mode selection circuit operate in a second boost mode when the output voltage of the LED driver is greater than the voltage of the DC power source plus a second threshold amount. – the operation of the converter topology and mode selection circuit is controlled by a controller operatively connected to a switch of the mode selection circuit. – the mode selection circuit includes the switch and a diode. – the diode is
- [20] US9992826B1_-_Dual_mode_constant_current_LED_driver__71bc120a — patent
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voltage. – FIG. 11C illustrates a graphical diagram of example results of operating the LED driver system of FIG. 10 in buck-boost mode, showing the output current as a function of input voltage. – FIG. 12A illustrates a graphical diagram of example results of operating the LED driver system of FIG. 10 in boost mode, showing the efficiency as a function of input voltage. – FIG. 12B illustrates a graphical diagram of example results of operating the LED driver system of FIG. 10 in boost mode, showing the input current as a function of input voltage. – FIG. 12C illustrates a graphical diagram of example results of operating the LED driver system of FIG. 10 in boost mode, showing the output current as a function of input voltage. – a dual mode constant output current power supply or so-called driver is disclosed. – the driver is capable of operating with a very wide range of input direct current (DC) voltage, and is particularly well-suited for powering switchable LED strings, but can also be used with other switchable load types as will be appreciated in light of this disclosure. – the mode of operation is adaptively selected to maximize the efficiency of the converter based on the output voltage conditions of the driver. By selecting the optimum mode in all output voltage conditions, the driver operates efficiently at high frequencies (e.g., greater than approximately 100 kHz) and provides high power density in a compact design. – the techniques can be used to provide an effec
- [24] An_Illuminating_Look_at_LED_Driving_Electronic_Design__3d16287f — magazine
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lower than the input. The boost driver (Fig. 2b) produces an output that’s higher than the input. The buck-boost can produce an output voltage that’s either higher or lower than the input voltage. There are several variations of the buck-boost, such as the floating buck-boost, the SEPIC, and the Cuk. The SEPIC and Cuk both require two inductors that add cost and take up more space. The SEPIC (shown in Fig. 4 below) is discussed later. LED Dimming A common need in LED lighting is dimming—controlling the brightness over a range from full off to the full brightness. Multiple dimming techniques have been developed using both linear and digital methods. In both, the brightness is determined by the average forward current in the LEDs. Over the current range of most LEDs, the relationship between average current and brightness is linear. Only at the high and low levels of current does the relationship become nonlinear. 3. A linear-current regulator driver IC sets the brightness by applying a dc input control voltage. Linear dimming is accomplished with a linear-current regulator IC (Fig. 3). A dc voltage controls the circuit, producing a linear current and brightness variation. Dimming ratios from 10:1 to 250:1 can be realized. While linear dimming is the simplest and easiest to implement, it may not fit the application. Some use cases require a wider dimming ratio that could be as high as 1000 or more to 1. Furthermore, linear dimming may produce an undesired color shift in color L
# Building a Versatile LED Driver Source: Blog/Web URL: https://www.electronicdesign.com/technologies/power/whitepaper/21156071/analog-devices-building-a-versatile-led-driver Author: Victor Khasiev Date: 2021-03-30 This article is part of the Power Management Series: Driving LED Designs What you'll learn: – Different topologies used in developing LED drivers. – Proper connections for buck, boost, and buck-boost configurations. – Test results for the three topologies using the same LED string. Today’s LED drivers are highly flexible, enabling their use in a wide array of applications from scanners to automobiles to avionic lighting. Many of these drivers can also be configured using multiple topologies —boost, buck, and buck-boost—to meet a wide variety of specific application requirements. For low input voltages and high string voltages, a boost topology is appropriate, whereas a buck is more suitable for high input voltages and low string voltages. A buck-boost topology is used for a wide range of inputs where voltage can be below or above the LED string. This article covers the process of selecting the suitable topology and its corresponding connections. For purposes of illustration, the examples are based on the LTM8042 µModule LED driver. This driver supports LEDs with up to 1-A current and a 3000:1 dimming ratio, operates from input voltages of 3 to 30 V, and has a frequency range of 250 kHz to 2 MHz. Boost LED Driver The most common topology for an LED driver is a boost
lighting (assuming that the lighting design incorporates multiple LED installations to compensate for shadows in a space measuring 4 feet square). The relatively low lumen output ratings of LED lamps are often times compensated for when looking at the foot-candle levels at the illuminated surfaces. In other words, for outdoor lighting applications, SolarOne estimates that an LED lamp rated at 45 lumens per watt will perform equivalently to a fluorescent bulb rated at 75 lumens per watt. This facet of LEDs offer an enormous side benefit to areas with dark-sky mandates. 2. Optimized system efficiency Solar cells and LEDs share many characteristics – even in the assembly process. For example, both solar cells and LEDs require sorting and balancing to optimize performance. The SOLED mc2 LED Lamp and Lamp Driver is configured to effectively eliminate the need for balancing resistors and their associated losses. Perhaps more significantly, through its range of testing and field experience, SolarOne has identified "sweet spots" in LED operation that optimize current flows and light levels with solar panel and battery costs. The trade-offs are quite different than grid-connected or even automotive applications. This translates into almost a 10% improvement in overall system efficiency. 3. Fine tuned to user needs
diagrams with the controller modulating the high-side switch for current control. Click image to enlarge Table 1. Advantages and Trade-Offs of Using Buck Converters as LED Drivers Several critical features to look for in step-down LED drivers are fixed frequency operation, high efficiency through excellent switching control and low resistance switches, high accuracy throughout the analog dimming range, and, for excellent EMI, a properly designed spread spectrum frequency modulation. Step-Up (Boost) Converters Step-up (or boost) LED drivers regulate the current in an LED string from a voltage that is lower than the total LED string voltage. This is useful in many automotive systems, where many LEDs need to conduct in a single string. Typical 12 V automotive systems have operational ranges from 6 V to 18 V — requiring that the LED driver runs down to 6 V, providing large step-up ratios for the LED store main illuminated. Figure 3 and an example schematic in Figure 2 show basic system diagrams with the controller modulating the low-side switch for current control. Click image to enlarge Figure 2. Boost converter example: LT8356-1 Click image to enlarge Table 2. Advantages and Trade-Offs of Using Boost Converters as LED Drivers Boost-Buck Using a Boost Converter Some step-up (or boost) LED drivers may be configured to return the LED cathode to the supply. This configuration is referred to as buck-boost. The total output voltage is VIN (VBATTERY), which is added to the total LED s
diagrams with the controller modulating the high-side switch for current control. Click image to enlarge Table 1. Advantages and Trade-Offs of Using Buck Converters as LED Drivers Several critical features to look for in step-down LED drivers are fixed frequency operation, high efficiency through excellent switching control and low resistance switches, high accuracy throughout the analog dimming range, and, for excellent EMI, a properly designed spread spectrum frequency modulation. Step-Up (Boost) Converters Step-up (or boost) LED drivers regulate the current in an LED string from a voltage that is lower than the total LED string voltage. This is useful in many automotive systems, where many LEDs need to conduct in a single string. Typical 12 V automotive systems have operational ranges from 6 V to 18 V — requiring that the LED driver runs down to 6 V, providing large step-up ratios for the LED store main illuminated. Figure 3 and an example schematic in Figure 2 show basic system diagrams with the controller modulating the low-side switch for current control. Click image to enlarge Figure 2. Boost converter example: LT8356-1 Click image to enlarge Table 2. Advantages and Trade-Offs of Using Boost Converters as LED Drivers Boost-Buck Using a Boost Converter Some step-up (or boost) LED drivers may be configured to return the LED cathode to the supply. This configuration is referred to as buck-boost. The total output voltage is VIN (VBATTERY), which is added to the total LED s
diagrams with the controller modulating the high-side switch for current control. Click image to enlarge Table 1. Advantages and Trade-Offs of Using Buck Converters as LED Drivers Several critical features to look for in step-down LED drivers are fixed frequency operation, high efficiency through excellent switching control and low resistance switches, high accuracy throughout the analog dimming range, and, for excellent EMI, a properly designed spread spectrum frequency modulation. Step-Up (Boost) Converters Step-up (or boost) LED drivers regulate the current in an LED string from a voltage that is lower than the total LED string voltage. This is useful in many automotive systems, where many LEDs need to conduct in a single string. Typical 12 V automotive systems have operational ranges from 6 V to 18 V — requiring that the LED driver runs down to 6 V, providing large step-up ratios for the LED store main illuminated. Figure 3 and an example schematic in Figure 2 show basic system diagrams with the controller modulating the low-side switch for current control. Click image to enlarge Figure 2. Boost converter example: LT8356-1 Click image to enlarge Table 2. Advantages and Trade-Offs of Using Boost Converters as LED Drivers Boost-Buck Using a Boost Converter Some step-up (or boost) LED drivers may be configured to return the LED cathode to the supply. This configuration is referred to as buck-boost. The total output voltage is VIN (VBATTERY), which is added to the total LED s
these components directly, but doing so involves significant trade-offs in system efficiency and robustness. Now consider adding a simple power electronics interface in the form of a battery charger and LED driver. This gives a much higher degree of flexibility and lets the designer optimize the overall system performance. A standalone battery-charger IC can manage the NiMH charging profile, and an LED driver IC can convert the battery voltage into a constant-current source. There is no real need to add a controller. However, there are at least two down sides to this discreet IC configuration. First, it limits the permissible range of operating conditions. ICs for managing batteries and driving LEDs often have a fairly narrow operating range, which limits the designer’s ability to make changes down the road or in response to customer requests. For instance, use of a new solar-cell configuration may necessitate use of a different battery-charging IC. If the energy-storage technology or configuration changes, it’s likely both the battery-charging IC and the LED-driver IC will have to go. And if there is a change in the type of LEDs or their series/parallel configuration, the LED driver will need to be reconfigured. The inclusion of a microcontroller helps handle these difficulties by providing some flexibility. Reprogramming can take the place of significant hardware changes. The second downside to the use of discrete ICs for these functions is that it makes system optimization
# Does LED efficiency increase with lower drive currents? Source: Blog/Web URL: https://forum.digikey.com/t/does-led-efficiency-increase-with-lower-drive-currents/6451 Author: Tilopa Date: 2020-05-07 Relative to arrays of strip LED lighting, I’ve heard people say that distributing current across more strips lowers the current for each strip and increases efficiency. Is this right? If so what type of efficiency are we talking about? I’m interested in increasing luminous efficiency, but I fail to see how diluting current by adding more strips increases efficiency. Wouldn’t each strip be just that much lower in luminous flux, and the sum total would be the same? Yes, operating a given emitter at reduced drive current levels typically does yield an increase in luminous efficacy (lumens/watt), because LEDs are not strictly linear in terms of this behavior. Higher per-strip drive levels promote higher operating temperatures, which depending on the scenarios one chooses to compare can cause reductions in efficacy on the order of 5 to 20%. Question about nominal drive current. “Nominal” drive current values typically indicate the level at which the other device characteristics are measured and communicated. Manufacturers generally choose this value to reflect an operating point that offers a good balance of competing design tradeoffs under expected operating conditions. Because different applications value different performance characteristics differently, it’s not necessarily the op
# LED lighting system design | Infineon Technologies Source: Blog/Web URL: https://www.infineon.com/applications/industrial/led-lighting-system-designs Author: Date: 2026-06-19 LED lighting system design Broad portfolio of semiconductor solutions for commercial and industrial LED lighting applications and systems – On this page Browse by category About We at Infineon have been focusing on LED drivers and connected and smart Lighting for many years. With our products and solutions, we are supporting high light and power quality in LED drivers as well as high efficiency of significantly above 90%. In the first step, the focus of the market has been on energy savings by just replacing incumbent light sources with LEDs. But due to further increase in energy cost and pressure on carbon footprint reduction, the efficiency of the LED drivers and the usage of presence detectors based on reliable radar technology are becoming more mainstream. Whatever your need, Infineon has you covered with our portfolio of LED driver ICs that support a platform approach for LED drivers in commercial and industrial lighting as well as indoor and outdoor LED lighting. A comprehensive portfolio of high-voltage MOSFETs and low-voltage MOSFETs, benchmark for linear- and switch-mode LED driver ICs, microcontrollers with dedicated peripherals for smart lighting system design and solutions, with high-efficiency power conversion, and dimming technologies as well as easy-to-use wireless communication and sens
unit. When one more LED is turned on, the current drops until the controller reacts and pushes the current up again. And when an LED is turned off (the corresponding switch being turned on) the current suddenly goes up until the feedback reduces it back to the desired level. – the battery voltage available for headlights can vary greatly, for example for a nominal 12V battery system, the headlights operates with no derating for the DC voltages from 8 to 24 volts and with derating down to 6 or up to 28 volts. There is a need for LED based automotive headlights with many individually-dimmable LEDs fed by compact and reliable derivers. – the LED driver of the present disclosure includes a converter topology, and a mode selection circuit that control the mode of the circuit based on the voltage to maximize efficiency of the LED driver. – the converter topology and mode selection circuit operate in a first buck-boost mode when the output voltage of the LED driver is less than the voltage of the DC power source plus a first threshold amount. – the converter topology and mode selection circuit operate in a second boost mode when the output voltage of the LED driver is greater than the voltage of the DC power source plus a second threshold amount. – the operation of the converter topology and mode selection circuit is controlled by a controller operatively connected to a switch of the mode selection circuit. – the mode selection circuit includes the switch and a diode. – the diode is
voltage. – FIG. 11C illustrates a graphical diagram of example results of operating the LED driver system of FIG. 10 in buck-boost mode, showing the output current as a function of input voltage. – FIG. 12A illustrates a graphical diagram of example results of operating the LED driver system of FIG. 10 in boost mode, showing the efficiency as a function of input voltage. – FIG. 12B illustrates a graphical diagram of example results of operating the LED driver system of FIG. 10 in boost mode, showing the input current as a function of input voltage. – FIG. 12C illustrates a graphical diagram of example results of operating the LED driver system of FIG. 10 in boost mode, showing the output current as a function of input voltage. – a dual mode constant output current power supply or so-called driver is disclosed. – the driver is capable of operating with a very wide range of input direct current (DC) voltage, and is particularly well-suited for powering switchable LED strings, but can also be used with other switchable load types as will be appreciated in light of this disclosure. – the mode of operation is adaptively selected to maximize the efficiency of the converter based on the output voltage conditions of the driver. By selecting the optimum mode in all output voltage conditions, the driver operates efficiently at high frequencies (e.g., greater than approximately 100 kHz) and provides high power density in a compact design. – the techniques can be used to provide an effec
lower than the input. The boost driver (Fig. 2b) produces an output that’s higher than the input. The buck-boost can produce an output voltage that’s either higher or lower than the input voltage. There are several variations of the buck-boost, such as the floating buck-boost, the SEPIC, and the Cuk. The SEPIC and Cuk both require two inductors that add cost and take up more space. The SEPIC (shown in Fig. 4 below) is discussed later. LED Dimming A common need in LED lighting is dimming—controlling the brightness over a range from full off to the full brightness. Multiple dimming techniques have been developed using both linear and digital methods. In both, the brightness is determined by the average forward current in the LEDs. Over the current range of most LEDs, the relationship between average current and brightness is linear. Only at the high and low levels of current does the relationship become nonlinear. 3. A linear-current regulator driver IC sets the brightness by applying a dc input control voltage. Linear dimming is accomplished with a linear-current regulator IC (Fig. 3). A dc voltage controls the circuit, producing a linear current and brightness variation. Dimming ratios from 10:1 to 250:1 can be realized. While linear dimming is the simplest and easiest to implement, it may not fit the application. Some use cases require a wider dimming ratio that could be as high as 1000 or more to 1. Furthermore, linear dimming may produce an undesired color shift in color L