The unprecedented development of the Internet of Things, as the core of the Internet of Things power technology has also followed, especially in the field of LED applications, highlighting the important position of power technology. With the improvement of people's environmental awareness and the improvement of living standards, more demands are placed on smart LED products, which makes LED power supply design also face many challenges, how to find power, size, current and voltage stability and other factors. The best balance is what every LED manufacturer must think about. As a semiconductor manufacturer, Rom and NXP, what are the high-tech initiatives in the LED driver field? Let us explain it together. For more information on IoT power supply design and related solutions, please pay attention to the "Power of IoT Core Technology" .
ROHM Digital Power Control Solution
As LED lighting, it needs to have a high-power product power source capable of driving small power products such as small lamps such as light bulbs to large-scale lighting such as street lamps. Moreover, this kind of power supply should be compatible with the "controllable silicon dimming" used in the original lighting fixtures, the "PWM dimming" dedicated to LED lighting, and the "linear dimming" which can be dimmed by bulk resistance. compatible.
In order to illuminate and dim the LED stably, an LED driver IC is required, and the driver IC is required to be compatible with various power sources such as power and dimming methods.
In the conventional method, the input voltage variation and the output voltage fluctuate greatly, and the power module must be redesigned according to the application conditions. If the input voltage fluctuates greatly, the rippled input voltage in the AC voltage frequency (100 Hz to 120 Hz after full-wave rectification) causes the brightness of the LED to flicker. In order to stabilize the input voltage, measures must be taken when designing the power module. If the output voltage fluctuates greatly, it is necessary to change the constant of the external component for each output voltage of the light source (the number of LEDs), and design a variety of power supply modules, thereby increasing the design workload.
Moreover, due to the varying Vf of the LEDs, the brightness of the LED lighting fixtures may be inconsistent.
The BD555AKFV developed by ROHM uses digital power control technology. Without increasing the number of external components, it is only necessary to detect the current of the coil to solve the above problems.
LED driver driver IC with thyristor dimming BD555AKFV block diagram
Due to the digital power control, the average value of the LED current can be controlled regardless of the input and output voltages (Figure 2). It digitizes the coil current (A/D conversion) and performs peak current calculation based on the sampled data to keep the average value of the LED current constant. Then, the operation result is D/A converted and fed back to the comparison circuit for detecting the peak current (Fig. 3-2). Rom uses this method to fully implement digital control, which is the first in the industry.
Although the digital power control method adopted by the switching power supply has attracted attention, it is difficult to apply to LED small-sized lighting because of the problem of "large circuit scale (high cost)" and "high power consumption" due to the use of the DSP. BD555AKFV has developed special logic for LED lighting functions, which solves the weakness of digital power supply - circuit and power consumption.
The digital power control feature is effective in utilizing the dimming function in addition to the average current control function. "BD555AKFV" is compatible with "dimmable silicon dimming", "PWM dimming" and "linear dimming" three dimming methods, and can be adapted to lighting fixtures with multiple dimming functions.
NXP High Efficiency Power Converter Solution
LEDs have been used in electronic systems for many years and are primarily used as indicators for electronic devices. The key driver for the development of the LED lighting market is the emergence of high-brightness LEDs and smart LED controllers. Key design challenges for product designers using high-brightness LEDs include thermal management, drive solutions, topologies, and existing infrastructure. To replace existing dimmable incandescent or halogen light sources, an electronic light drive system must be implemented that not only works with existing dimmer switches, but also replicates the dimming performance of existing light sources.
NXP (NXP) SSL2101 IC can meet the above performance requirements. In addition, it is an efficient power converter. This is the industry's first IC to integrate these capabilities, enabling high-brightness LED lamp designers to integrate electronic circuits in a cost- and volume-efficient manner and benefit from optimal thermal trade-offs.
Serial/parallel configuration
In most applications where LEDs are used in place of existing sources, multiple LEDs need to be connected to the driver because a single LED does not produce sufficient luminous flux. LEDs can be connected in series or in parallel. If the LEDs are connected in series, the total voltage on the LED chain is equal to the sum of the forward voltages (the currents on all LEDs are equal). If the LEDs are connected in parallel, current will be distributed to each branch. However, since the forward voltage of an LED drops as the temperature rises, this configuration is inherently unstable. As the temperature increases, more and more current will flow to the branch with a lower forward voltage, these branches will become brighter, and those with higher forward voltage will become Darker.
However, one reason for using a parallel configuration (or a series-parallel combination) is that it allows a large number of LEDs to be combined together with a safe supply voltage, and if a serial connection is used to achieve the same brightness, a high order may be required. The voltage that people cannot accept.
Parallel configuration also offers other advantages. If there is a problem with an LED or connection on a serially connected LED chain, it will cause an open circuit and all LEDs on the entire chain will not illuminate. However, this situation will not be possible if a parallel configuration is used. When using a parallel configuration, it is recommended to add a current regulation mechanism to each branch to prevent thermal runaway and unequal current or light.
In summary, the power converter is most efficient when the output and input voltage differences are minimal. When using a mains input LED driver, a higher output voltage is allowed, allowing more LEDs to be connected in series.
NXP SSL210X typical application
NXP SSL210X Secondary Side Constant Current IC Application
â—Customer wants high current accuracy to use special constant current IC
â— Constant current IC RT8456 is specially used for LED constant current drive
â— Constant current IC is placed on the secondary side, and no secondary DC/DC conversion is performed to improve performance.
Introducing Richtek RT8456
2inch Bluetooth Thermal Printer is a very popular Mini Bluetooth Printer. Qunsuo is the manufacturer, supporting us provide high quality Bluetooth Pos Printer. 2inch Bluetooth Thermal Printer are widely use for thermal receipt printing. What's more, it can also use as shipping label printer. Qunsuo printers support connecting with Android, IOS, Windows, WinCE, Symbian multi ststems.
2inch Bluetooth Thermal Printer
Mini Bluetooth Printer,Bluetooth Shipping Label Printer,Bluetooth Pos Printer,Printer Bluetooth Mini
Shenzhen Qunsuo Technology Co., Ltd , https://www.qsprinter.com