The Kynix Blog - LED

Overview: This article explores LED drivers, their types, design considerations, and applications, highlighting how they ensure efficient, reliable, and long-lasting LED lighting systems.Light-emitting diodes (LEDs) are semiconductor devices that have become the primary technology for modern lighting applications, from smartphone displays to large-scale digital billboards. Beyond visible light applications, LEDs serve various specialized functions. Recent advances have significantly improved their cost-effectiveness and performance, leading to wide adoption across multiple industries.Unlike conventional incandescent or fluorescent lights, LEDs require precise current regulation to function properly. Direct connection to a power source without proper current control can result in device failure or reduced lifespan. LED drivers address this fundamental requirement by providing the necessary current regulation and voltage conversion.What is an LED driver?An LED driver is a power regulation circuit designed to control the electrical characteristics supplied to an LED or LED array. The primary function of an LED driver is to maintain constant current output in varying input voltage and environmental conditions.LED driver performance directly impacts LED system efficiency and reliability. To maximize the advantages of LED technology, drivers must meet several design requirements: high power conversion efficiency, compact form factor, proper construction for extended operation, compliance with electromagnetic compatibility standards, and precise current control across varying load conditions.Types of LED DriversBased on the integration of the driver with the LED systemThere are two types, as shown in Fig. 1Integrated driverExternal driver Fig. 1 Integration of the driver with the LEDs: a) Integrated driver, b) External driver. Source: IEEE AccessIntegrated driverIn an integrated structure, the driver is built into the fixture, offering a simple, compact installation but potential heat management issues as the driver and LEDs share a single housing. There are two types: internal drivers, which are permanently installed and require replacement of the whole fixture if they fail, and plug-and-play drivers, which are replaceable via standard connections. They are ideal for residential and small commercial spaces.External driverExternal structures keep the driver separate from the LEDs, enabling better heat dissipation and a longer lifespan, but installation is more complex due to wiring, electromagnetic interference, and grounding requirements. These are preferred for outdoor, street, and industrial lighting where reliability and longevity are most important.Based on primary operating modes:LED drivers are classified into two typesConstant Current (CC) LED driversConstant Voltage (CV) LED driversThese fundamental approaches determine how the driver maintains stable output characteristics under varying load and input conditions.Constant current driversLEDs are highly sensitive to current changes; excessive current can cause overheating and failure, while insufficient current results in poor brightness. CC LED drivers provide a stable current to LEDs, regardless of fluctuations in their forward voltage or changes in the number of LEDs connected in series, up to the driver’s maximum voltage limit. By maintaining a steady current, CC drivers maximize LED lifespan and ensure consistent performance.CC drivers are preferred for high-power LEDs, such as those used in street lighting, high-bay fixtures, and commercial signage, where consistent brightness and reliability are essential. Typical output currents for commercial CC drivers are 350 mA, 700 mA, 1050 mA, and others. CC drivers are compatible with both constant current reduction (also called analog dimming) and pulse width modulation (PWM) dimming methods.Constant voltage driversConstant voltage drivers maintain a stable voltage output across the LED load while allowing current to vary within specified operating limits. Since LEDs require precise current for optimal operation, CV driver systems typically incorporate impedance elements (such as current-limiting resistors) between the driver output and LED connections.Commercial CV drivers commonly provide standardized output voltages of 12 V and 24 V, corresponding to typical LED strip and module voltage requirements. Unlike CC drivers, CV drivers require only PWM control to maintain proper LED current regulation during dimming operations.Based on different circuit topologiesBoth regulation CC and CV modes can be implemented using various circuit topologies, includingBuckBoostBuck-BoostSEPIC(Single-Ended Primary Inductor Converter)FlybackCukCharge PumpBased on their input power sourceLED systems fall into two main categories, as shown in Fig. 2AC-supplied systemDC-supplied systems Fig. 2 Classification of LED systems based on power source. a) AC-LED system b) DC-LED system Source: IEEE AccessAC-supplied LED systems use different circuit blocks than their DC counterparts and can power both DC-LED modules and AC-LED modules. DC-LED systems are applied in direct current-powered environments, including automotive systems and Power-over-Ethernet applications.ApplicationsAn LED driver has several key applications, each with distinct requirements, which are listed below. General lighting includes indoor systems like bulbs, lamps, and tubes, which are AC-powered, cost-sensitive, and must efficiently manage heat within compact designs. Street lighting is subject to temperature swings and surges, demanding an improved thermal and magnetic design, strong surge protection, and sometimes powers IoT or telecom features for smart city integration.Automotive lighting, including both exterior (headlights, tail lights) and interior (cabin, dashboard), requires high reliability and efficiency, to handle large voltage fluctuations, transients, and low quiescent current to avoid draining batteries.Specialized LED lighting includes grow lights, which offer tunable spectra for plants and require low ripple and humidity-safe, multi-string drivers. UV LEDs are used for curing and disinfection, with flexible power needs. Portable lights prioritize efficiency, robustness, and low weight. Decorative lights focus on low cost and multi-color support. Signage/traffic lights demand high reliability, efficiency, and operation under harsh conditions.Display LED applications cover large billboards and micro-LED panels, which use multiplexing and parallelization for high-quality visuals. LCD backlighting relies on efficient, high-contrast dimming for optimal battery life and image quality. LED animation enables dynamic color mixing and pattern control, while status indication requires precise current for uniform brightness and longevity.Future trends in LED drivers focus on higher efficiency, greater integration, and smart connectivity for IoT and emerging uses like visible light communication.An effective LED driver to considerTexas Instruments TPS92512 It is a highly efficient, integrated buck (step-down) LED driver designed to power high-brightness LEDs in a variety of lighting applications. It operates over a wide input voltage range of 4.5 V to 60 V, making it suitable for both low- and high-voltage systems. The device can deliver up to 2.5 A of output current and features an integrated MOSFET, which simplifies the design and minimizes external components. Fig. 3 TPS92512 Buck LED Driver. Source: Texas InstrumentsThe TPS92512, as shown in Fig. 3, supports analog and PWM dimming, providing flexible brightness control for different lighting needs. Its robust design and precise current regulation makes it ideal for commercial, industrial, emergency, and street lighting applications, where reliability and efficiency are essential.Summarizing the Key PointsLED drivers are essential for regulating current and voltage, ensuring LED longevity, stability, and optimal performance across various lighting applications and environmental conditions.Designing LED drivers involves considerations for efficiency, thermal management, EMI standards, and matching electrical characteristics to prevent system limitations and ensure reliability.Future LED driver developments focus on higher efficiency, greater integration, IoT connectivity, and support for advanced lighting solutions like visible light communication.ReferenceEsteki, M., Khajehoddin, S. A., Safaee, A., & Li, Y. (2023). LED Systems Applications and LED Driver Topologies: A review. IEEE Access, 11, 38324–38358. https://doi.org/10.1109/access.2023.3267673Lamar, D. G. (2020). Latest developments in LED drivers. Electronics, 9(4), 619. https://doi.org/10.3390/electronics9040619LED drivers | TI.com. (n.d.). https://www.ti.com/power-management/led-drivers/overview.htmlFoolish Engineer. (2024, September 15). How to drive LED? What Is LED Driver? Understanding LED Driver | LED Drivers [Video]. YouTube. https://www.youtube.com/watch?v=XDhOvJ_TexETexasInstruments TPS92512- https://www.kynix.com/productdetails/3119083/texasinstruments/tps92512dgqr.htmlTPS92512HV | Buy TI Parts | TI.com. (n.d.). https://www.ti.com/product/TPS92512HV/part-details/TPS92512HVDGQT

Catalog PurposeHardwareSofowareConclusion Smart homes have been a popular topic for several years now. With the rapid development of technology, it has become easier and more affordable for people to make their homes smart. One of the simplest and most useful smart home projects is a smart light. In this article, we'll show you how to use a Raspberry Pi to make a smart light. A smart light turns on automatically when you enter the room and turns off when you leave, saving energy and providing a more convenient experience. This project is a great way to learn about the Raspberry Pi and how to control it using Python, making it a great choice for both beginners and experienced makers. Purpose The purpose of this project is to create a smart light that is convenient, energy-efficient, and saves you time. This smart light can be controlled using motion detection, so when you enter the room, the light will turn on automatically, and when you leave, the light will turn off. This feature will save energy, as you don't have to manually turn the light off, and it will also provide a more comfortable experience. Hardware Building a smart light using a Raspberry Pi involves connecting several hardware components together to form a complete system. The process involves connecting a PIR (Passive Infrared) sensor to the Raspberry Pi, which detects motion in the room. The Raspberry Pi is then connected to a relay module, which acts as an intermediary between the PIR sensor and the  LED light. Finally, the LED light is connected to the relay module to provide illumination. The following is a list of the hardware components required for this project: 1. Raspberry Pi - a credit-card sized computer that can be used for a variety of projects. 2. PIR sensor - used to detect motion in the room and trigger the relay module to turn on oroff the LED light. 3. Relay module - used to switch the LED light on and off based on the input from the PIR sensor. 4. LED light - used to provide illumination in the room. 5. Power supply for the Raspberry Pi - used to power the Raspberry Pi and its components. 6. Jumper wires - used to connect the components together. 7. Bread board - used to create a prototype circuit for the project. Purchase on Kynix1Raspberry Pi2PIR sensor3Relay module4LED light5Power supply6Jumper wires7Bread board It is important to use a relay module for this project because the Raspberry Pi does not have enough power to directly control the LED light. The relay module provides an isolated circuit between the Raspberry Pi and the LED light, making it safe to use and preventing damage to the Raspberry Pi. The use of a breadboard allows you to easily modify and test the circuit, making it easier to troubleshoot any problems that may arise. Below is the description of circuit diagram:1. Connect the PIR sensor to the Raspberry Pi. The PIR sensor has three pins: VCC (power), GND (ground), and OUT (output). Connect the VCC pin to the 5V pin on the Raspberry Pi, the GND pin to a GND pin on the Raspberry Pi, and the OUT pin to a GPIO pin on the Raspberry Pi (for example, GPIO 18).2. Connect the LED light to the Raspberry Pi. The LED light has two pins: anode (+) and cathode (-). Connect the anode to a GPIO pin on the Raspberry Pi (for example, GPIO 23) and the cathode to a GND pin on the Raspberry Pi.3. Connect a resistor to the anode of the LED light. This resistor is used to limit the current flowing through the LED and protect it from damage. The value of the resistor will depend on the forward voltage and forward current of the LED, which are specified by the manufacturer. A common value is 220 ohms.4. Connect the Raspberry Pi to a power source, such as a micro USB cable, to provide power to the Raspberry Pi and all of the connected components. Software In order to turn your Raspberry Pi into a smart light, you will need to write code using Python and the RPi. GPIO library. This library provides an easy way to control the GPIO pins on the Raspberry Pi, allowing you to read from sensors and control other components like the relay module and LED light. Before writing the code, you need to install the RPi. GPIO library on your Raspberry Pi. You can do this by running the following command in the terminal:sudo apt-get install python-rpi.gpio Alternatively, you can install the library using pip by running the following command:pip install RPi.GPIO Once the library is installed, you can start writing your code. The following is an example of the code needed to create a smart light using a Raspberry Pi:1. Import the RPi.GPIO library:            import RPi.GPIO as GPIO                                                     2. Set the GPIO pin mode:           GPIO.setmode(GPIO.BCM)                                                      3. Set the GPIO pin for the PIR sensor and relay module as inputs:            GPIO.setup(PIR_PIN, GPIO.IN)                                                           GPIO.setup(RELAY_PIN, GPIO.OUT)                                             4. Createaloop to check the PIR sensor and turn the relay module and LED light on or off:            while True:                                                                                  if  GPIO.input(PIR_PIN):                                                                      GPIO.output(RELAY_PIN, True)                                                             print("Motion detected, turning on light")                                          else:                                                                                   GPIO.output(RELAY_PIN, False)                                                       print("No motion detected, turning off light")                     5. Clean up the GPIO pins before exiting the program:              GPIO.cleanup()                                                              This code uses the RPi. GPIO library to check the PIR sensor for motion and turn the relay module and LED light on or off accordingly. The code uses a while loop to continuously check the PIR sensor and update the status of the relay module and LED light. The GPIO.cleanup() function is used to clean up the GPIO pins before the program exits, preventing any potential conflicts with other programs that may be using the same pins. Conclusion In this article, we have explored how to use a Raspberry Pi to create a smart light that turns on and off based on motion detection. We have discussed the hardware required, including a Raspberry Pi, PIR sensor, relay module, and LED light. We also provided a code example using the RPi. GPIO library to check the PIR sensor and control the relay module and LED light. Building a smart light using a Raspberry Pi is a simple and cost-effective project that can be completed in a few hours. It provides a great introduction to using the Raspberry Pi and the RPi.GPIO library and can be easily modified to meet your specific needs. Whether you are looking to automate your home or just interested in learning more about the Raspberry Pi, building a smart light is a great starting point.

Introduction There are many kinds of LCD interfaces, with wide range of applications. The classification criteria mainly depends on the driving mode and control mode of the LCD. At present, there are generally several connection modes for color LCDs on mobile phones: MCU mode, RGB mode, SPI mode, VSYNC mode, MDDI mode, DSI mode, etc. and only the TFT module has RGB interface. Basics of LCD Interfacing Catalog Introduction Ⅰ LCD Interface Modes 1.1 MCU Mode 1.2 VSYNC Mode 1.3 M6800 Mode 1.4 Intel 8080 Mode 1.5 RGB Mode 1.6 SPI (Serial Peripheral Interface) Mode 1.7 MDDI (Mobile Display Digital Interface) Mode 1.8 DSI (Display Serial Interface) Mode Ⅱ MCU Mode vs RGB Mode Ⅲ TFT-LCD Interface Explained 3.1 TTL Interface 3.2 LVDS 3.3 EDP (Embedded Display Port) 3.4 MIPI Interface Ⅳ FAQ Ⅰ LCD Interface Modes The following is a detailed explanation of the different interface modes: 1.1 MCU Mode It is mainly used in the field of single-chip microcomputers. Later, it is widely used in low-end mobile phones, and its main feature is that it is cheap. The standard term for the MCU-LCD interface is the 8080 bus standard proposed by Intel. Figure 1. Intel 8080 Therefore, 8080 is used to refer to the MCU-LCD screen in many documents. It can be mainly divided into 8080 mode and 6800 mode, and the difference between the two is mainly the timing. There are 8 bits, 9 bits, 16 bits, 18 bits, and 24 bits for data bit transfer. Connections are divided into: CS/, RS (register selection), RD/, WR/, and data lines. The advantages are: the control is simple and convenient, no clock and synchronization signals are required. The disadvantage is: it consumes GRAM, so it is difficult to achieve a large screen (above 3.8). For LCM with MCU interface, the internal chip is called LCD driver. The main function is to transform the data/command sent by the host into the RGB data of each pixel, so that it can be displayed on the screen. This process does not require point, line, frame clocks.The LCD Driver IC of the MCU interface is equipped with GRAM. As a co-processor of the MCU, it accepts the Command/Data sent by the MCU and can work relatively independently. Pay attention to, the internal chip of LCD Module (LCM) is called the LCD driver. The main function is to transform the data/commands sent by the host computer into the RGB data of each pixel, so that it can be displayed on the screen. This process also does not require point, line, frame clocks. 1.2 VSYNC Mode In fact, this mode is to add a VSYNC signal to the MCU mode and applied to the update of the moving picture, which is very different from the above interface. This mode supports the function of direct animation display. It provides a solution for animation display with minimal changes to the MCU interface. In this mode, the internal display operation is synchronized with the external VSYNC signal. Animation display at a higher rate than internal operations can be achieved. However, due to the difference in its operation mode, this mode has a limit on the speed, that is, the write speed to the internal SRAM must be greater than the speed of the display read internal SRAM. 1.3 M6800 Mode The M6800 mode supports selectable bus widths of 8/9/16/18-bit (the default is 8 bits). The actual design idea is the same as that of Intel 8080. The main difference is the bus control read and write signals in this mode. Combined on one pin (with a latch signal (E) data bit transmission has 8, 9, 16 and 18 bits). Figure 2. M6800 Mode 1.4 Intel 8080 Mode Intel 8080 LCD interface is divided into: CS/, RS (register selection), RD/, WR/, and the data line. Advantage: Simple and convenient control, no clock and synchronization signals are required. Disadvantage: It consumes GRAM, so it is difficult to achieve a large screen (above QVGA). Figure 3. Intel 8080 Mode 1.5 RGB Mode The large screen adopts more modes, and the data bit transmission also has the 6-, 16- and 18-, 24-bit. The connections are generally: VSYNC, HSYNC, DOTCLK, CS, RESET, some also need RS, and the rest is the data line. Its advantages and disadvantages are just the opposite of MCU mode. The main difference between the MCU-LCD screen and the RGB-LCD screen is the location of the video memory. The video memory of RGB-LCD is acted by system memory, so its size is only limited by the size of system memory. Where RGB-LCD can be made larger, such as 4.3" can only be regarded as entry-level, and 7" in MID, 10" screens have begun to be widely used. At the beginning of the design of MCU-LCD, it was only necessary to consider that the memory of the single-chip microcomputer was small, so the video memory was built into the LCD module, and then the software updated the video memory through special display commands with small MCU screen. At the same time, the display update speed is slower than RGB-LCD. The display data transmission mode is also different. RGB screen only needs to organize the data in the video memory. After starting the display, the LCD-DMA will automatically transfer the data in the video memory through the RGB interface to the LCM, while the MCU screen needs to send a drawing command to modify the internal RAM of the MCU (that is, the RAM of the MCU screen cannot be directly written).Therefore, the RGB display speed is significantly faster than that of the MCU, and the MCU-LCD is also slower in terms of video playback. For the LCM of the RGB interface, the host directly outputs the RGB data of each pixel without conversion (except for GAMMA correction, etc.). For this interface, an LCD controller is required in the host part to generate RGB data and sync signals. Figure 4. RGB Mode Here gives a note. The color TFT LCD screen mainly has 2 kinds of interfaces: TTL interface (RGB color interface), and LVDS interface (differential signal transmission). The TTL interface is mainly used for small-sized TFT screens below 12.1 inches, and the LVDS interface is mainly used for large-sized TFT screens above 8 inches. The TTL interface has many lines and the transmission distance is short, while the LVDS interface has a long transmission distance and a small number of lines. The large screen adopts more modes, the control pins are VSYNC, HSYNC, VDEN, VCLK, S3C2440 supports up to 24 data pins, and the data pin is VD[23-0].The image data sent by the CPU or graphics card is a TTL signal (0-5V, 0-3.3V, 0-2.5V, or 0-1.8V), and the LCD itself also receives a TTL signal, which is transmitted at a high rate over long distances. However, its performance is poor, and the anti-interference ability is relatively poor. With the time goes by, a variety of transmission modes were proposed, such as LVDS, TDMS, GVIF, P&D, DVI and DFP. They actually just encode the TTL signal sent by the CPU or graphics card into various signals for transmission, and decode the received signal on the LCD side to obtain the TTL signal. No matter what transmission mode is used, the essential TTL signal is the same. Note: TTL/LVDS are two signal transmission modes: TTL is a mode in which high level means 1, and low level means 0; LVDS is the difference of a positive and negative corresponding waveform used to indicate the 1 or 0. 1.6 SPI (Serial Peripheral Interface) Mode It is less used. There are 3-wire and 4-wire, the connection is CS/, SLK, SDI, and SDO, and the software control is more complicated. 1.7 MDDI (Mobile Display Digital Interface) Mode  Qualcomm's MDDI, which can improve the reliability of mobile phones and reduce power consumption by reducing wiring. It will replace SPI mode as a high-speed serial interface in the mobile field. The main connection is host_data, host_strobe, client_data, client_strobe, power, and GND. 1.8 DSI (Display Serial Interface) Mode This mode is a serial bidirectional high-speed command transmission mode, with D0P, D0N, D1P, D1N, CLKP, CLKN connected.   Ⅱ MCU Mode vs RGB Mode Among them, there are more applications in MCU mode and RGB mode. The differences are as follows:1) MCU interface: it will decode commands, generate timing signals by timing generator, and drive COM and SEG.RGB interface: When writing LCD register setting, it is no different from MCU interface. The difference is only in how the image is written.2) When using the MCU mode, since the data can be stored in the IC's internal GRAM first and then written to the screen, the LCD in this mode can be directly connected to the memory bus. It is different when using RGB mode, and has no internal RAM, HSYNC, VSYNC, ENABLE, CS, RESET, RS can be directly connected to the GPIO port of memory, and use the GPIO port to simulate waveforms.3) MCU Interface vs RGB InterfaceThe main differences between the MCU interface and the RGB interface are:MCU interface mode: display data is written into DDRAM, often used for still picture display.RGB interface mode: The display data is not written into DDRAM, but directly written to the screen, which is fast and often used to display video or animation.   Ⅲ TFT-LCD Interface Explained The commonly used interfaces of TFT-LCD, including TTL (RGB), LVDS, EDP, and MIPI. Here roughly talk about the basic principles of the signal composition of these interfaces. Figure 5. TTL (Transistor-Transistor Logic) Schematic 3.1 TTL Interface 🔺Interface OverviewTTL is transistor-transistor logic, and TTL level signals are generated by TTL devices. TTL devices are a large category of digital integrated circuits. They are manufactured by bipolar technology and have the characteristics of high speed, low power consumption and many varieties.The TTL interface is an interface for transmitting data in parallel. When using it, it is not necessary to use a dedicated interface circuit at the driver board end and the LCD panel end of the liquid crystal display, but the TTL data signal output by the main control chip of the driver board is transmitted through the cable. It is directly transmitted to the input interface of the LCD panel. Due to the high signal voltage, many connections and long transmission cables of the TTL interface, the anti-interference ability of the circuit is relatively poor, and it is easy to generate electromagnetic interference (EMI). In practical applications, TTL interface circuits are mostly used to drive small-size (below 15in) or low-resolution LCD panels. The highest pixel clock of TTL is only 28MHz.TTL is the only signal that TFT-LCD can recognize. Early digital processing chips are all TTL, that is, RGB is directly output to TFT-LCD.🔺Signal TypesThe TTL output interface of the driver board generally includes three types of signals: RGB data signal, clock signal and control signal. As shown below:(1) RGB Data-Signala. Single Channel6-BitAs for it, there are 18 RGB data lines in total, including 6 R0~R5 red primary color data lines, 6 G0~G5 green primary color data lines, 6 B0~B5 blue primary color data lines, a total of 18 strips. Since the primary color RGB data is 18bit, it is also called 18-bitTTL interface.8-BitFor it, there are a total of 24 RGB data lines, including 8 R0~R7 red primary color data lines, 8 B0~B7 green primary color data lines, 8 BO~B7 blue primary color data lines, a total of 24 strips. Since the primary color RGB data is 24-bit, it is also called 24-bit TTL interface.b. Dual ChannelDual channels, that is, two sets of RGB data, which are divided into odd channels and even channels. Some clocks are also divided into OCLK/ECLK, and some share one. The following figure has two, as shown below:6-BitIt has 36 RGB data lines in total, including 18 odd RGB data lines, 18 even RGB data lines. Since the primary color ROB data is 36-bit, it is also called 36-bitTTL interface.8-BitIt has 48 RGB data lines, including 24 odd RGB data lines and 24 even RGB data lines. Since the primary color RGB data is 48bit, it is also called 48-bit TTL interface.(2) Clock SignalIt refers to the pixel clock signal, which is the benchmark for transmitting data and reading the data signal. When using odd/even pixel dual way to transmit RGB data, different output interfaces use different methods of pixel clock. Some output interface odd/even pixel dual data share a pixel clock signal, and the others set odd pixel data clock and even pixel two clock signals to meet the needs of different LCD panels.(3) Control SignalThe control signals include a data enable signal (or an effective display data strobe signal) DE, a horizontal sync signal HS, and a vertical sync signal VS. 3.2 LVDS 🔺Overview of LVDS InterfaceLVDS is a low-voltage differential signaling technology interface. A digital video signal transmission method developed to overcome the shortcomings of large power consumption and large EMI electromagnetic interference when transmitting broadband high bit rate data in TTL level mode. The LVDS output interface uses a very low voltage swing (about 350mV) to transmit data differentially on two PCB traces or a pair of balanced cables, that is, low-voltage differential signaling. Using the LVDS output interface, the signal can be transmitted at a rate of several hundred Mbit/s on the differential PCB line or balanced cable. Due to the low-voltage and low-current driving method, low noise and low power consumption are achieved.🔺Composition of LVDS Interface CircuitIn a liquid crystal display, the LVDS interface circuit includes two parts, the LVDS output interface circuit (LVDS transmitter) on the motherboard side and the LVDS input interface circuit (LVDS receiver) on the LCD panel side. The LVDS emitter converts the TTL signal into an LVDS signal, and then transmits the signal to the LVDS decoding IC on the receiving end through the flexible cable (line) between the driver board and the LCD panel, and the LVDS receiver then serializes the serial signal which is converted into a parallel signal of TTL level, and sent to the LCD screen timing control and row and column drive circuit. In other words, TFT only recognizes TTL (RGB) signals.🔺Signal type of LVDS interfaceLVDS signals are composed of data differential and clock differential signals. As shown below:(1) Single Channel6-Bit DataThere are 4 sets of differential lines, 3 sets of signal lines, and one set of clock lines, including Y0M, Y0P, Y1M, Y1P, Y2M, Y2P, CLKOUT_M, CLKOUT_P.8-Bit DataThere are 5 groups of differential lines, 4 groups of signal lines, and a group of clock lines. They are Y0M, Y0P, Y1M, Y1P, Y2M, Y2P, CLKOUT_M, CLKOUT_P.(2) Dual ChannelWhen LVDS transmits data with higher resolution, the anti-interference ability is relatively strong. But when the resolution is higher than 1920×1080, the single channel is overwhelmed, so there is a dual interface. Its purpose is very simple, speed up and enhance anti-interference ability.6-Bit DataIt is exactly twice as long as the single channel, and the clock is also two channels. The red part: the two sets of signals: Y3M, Y3P, Y3M1, and Y3M1 are not connected.8-Bit DataSimilar to the previous comparison. 3.3 EDP (Embedded Display Port) EDP is a communication interface of the computer display screen. The resolution of the computer using the EDP display interface will be higher than that of the LVDS interface. Generally, high-definition screens use this communication interface. It is a fully digital interface based on the DisplayPort architecture and protocol. It can transmit high-resolution signals with simpler connectors and fewer pins, and can achieve simultaneous transmission of multiple data, so the transmission rate is much higher than LVDS. 3.4 MIPI Interface Compared with the LVDS interface, the MIPI interface is rare, but in fact, it has many advantages. The MIPI interface module has the advantages of high speed, large amount of data transmission, low power consumption, and good anti-interference when compared with the parallel port. It is more and more favored by customers and is growing rapidly. For example, an 8M module with both MIPI and parallel port transmission requires at least 11 transmission lines and an output clock of up to 96M to achieve a full pixel output of 12FPS when using an 8-bit parallel port. Channel 6 transmission lines can achieve a frame rate of 12FPS at full pixels, and the current consumption will be about 20MA lower than that of parallel port transmission. Since MIPI uses differential signal transmission, the design needs to be strictly designed according to the general rules of differential design. The key is to achieve differential impedance matching. The MIPI protocol stipulates that the differential impedance of the transmission line is 80-125 ohms.   Ⅳ FAQ 1. What is LCD interface?16x2 LCD means that there are two rows in which 16 characters can be displayed per line, and each character takes 5X7 matrix space on LCD. ... In this tutorial we are going to connect 16X2 LCD module to the 8051 microcontroller (AT89S52). 2. What is LCD parallel interface?LCD Displays that use a parallel interface include Character, Graphic and TFT. ... The initial step is to energize the LCD. Reads and Writes are sent via 8 data lines and 3 control lines. These control lines are Read/Write (R/W), Enable (E) and Register Select (RS). 3. What is TFT interface?A TFT LCD display module consists of a TFT LCD panel, one or more COG (chip-on-glass) or COB (chip-on-board) driver ICs, a backlight, and an interface. Several TFT display interface technologies exist today. Picking the right interface depends on specific end-product concerns. 4. What are the different types of LCDs?Different Types of LCD PanelsTwisted Nematic (TN) Twisted Nematic LCDs are the most commonly manufactured and used types of monitors across a wide range of industries. ...IPS Panel TechnologyVA PanelAdvanced Fringe Field Switching 5. What is MCU interface?The MCU interface has two standard types, the Intel-8080 and Motorolla-6800 series. These interfaces communicate through read, write and chip-select signals to address registers or display RAM. The slight difference between the two pertains to the direction and separation of the write and read signals. 6. What is MCU interface LCD?These interfaces communicate through read, write and chip-select signals to address registers or display RAM. Depending on color depth (8, 9, 16 or 18-bit), MCU sends RGB signals directly to LCM's display memory. 7. Is TFT an LCD?TFT is a kind of LCD. The TFT(Thin Film Field-effect Transistor) is a video in which every single pixel in the liquid crystal display is actuated by a Thin Film Transistor embedded in the rear. Thus can achieve high speed, high brightness, high contrast display screen information.

Summary Last days,I bought a new house and I am considering how to decorate it. when thinking about wall-lighting sconces.My project is to place an array of LED strips on the walls,covered with translucent(or in some cases,opaque!) Yeah,Plexiglas plates mounted a few centimetres away. That's the plan anyway...   Preparation At first, I need a 18W power supplies small enough to fit into an electrical box.Finally,I chose a power supply.This product could provide a full 1.5A without collapsing.However,upon opening the cases,the component temperatures after rumming at full-throttle for a new minutes suggested otherwise.The switching transistor,output rectifier,and output capacitor were all far too hot for comfort.I imagine the 18W spec is only valid for one day of use. Figure 1  The 12V 18W PSU. Notice the 100% efficiency (IN & OUT are both 18W), and  the dire warning not to touch the surface of the plastic case because of high temperature   I also bought one PSU from Aliexpress.They behave differently than the first batch. From an external vantage point, they’ll only supply 1.3A as opposed to the former 1.5A. The output voltage collapses to 8V at 1.5A.Take it apart, and further differences appear. Most noticeably, the 12V output capacitor does not egregiously overheat at, say, 1.3A. Sure enough, the part has “Low ESR” printed on the case. The previous caps don’t. Figure 2  PSUs from AliExpress (top) and another, forgotten source (bottom). Note the  convenient dates at the bottom of the boards. Manufacture has transitioned from phenolic to fiberglass   The design appears to be a simple self-oscillating circuit. I measured the switching frequency to be about 100 kHz. The 12V output caps are at the upper-right of each board. Though the legend says “1000µF 25V”, the installed caps are 470µF.   After discovering the output cap heat problem (but before getting the second PSU batch), I sourced a bagful of quality capacitors – 270µF @ 35V, still more than enough capacitance for this circuit, but with a high ripple-current rating and low ESR. Both of the boards above have these new parts installed. They run cool as a cucumber, versus the slight temperature rise of the second PSU caps, and of course, the extreme rise of the first ones. Figure 3  The PCB bottoms reveal other minor design changes in the newer boards – mainly exposed copper to pick up current-fortifying solder   I’m constantly struck by the strange state of affairs at this level of Chinese manufacture. Clearly, there is some thought and skill put into design and production, yet we still end up with stupidities, like unsuitable parts, or wishful-thinking specs. As I mentioned, other parts get hot too. The switching transistor can get toasty at higher loads, but it was the output rectifier I focused my measurements on. At 1.33A, free-air TC registered 90°C. At 1.2A, 86°C. Figure 4  My test setup here at EDN Labs. Note the many safety protocols employed on the bench   Enclosed in its case, in an electrical box, I don’t think I’ll want to pull more than 1.1A from these PSUs. Hopefully, that will be enough for my LED lighting. Other options: Squeeze two PSUs into a box (possibly swapping the case for some shrink wrap or electrical tape), or, cut a hole in the case so I can bend the rectifier out and heat-sink it to the electrical box! Hmm. We’ll see.   Result I didn't realize my plan until now.I am so tangle should choose which one? The last one,there is an absence of an AC line filter on the board.The former, at least, has a line filter, and even if they also don’t meet their output-current spec, they will certainly be better than the PSUs I’m using. But…they don’t fit into an electrical box.How do you think about my plan? Anyaway,I will attempt it again when I am free.  

SummaryAs we all known,better knowledge of the absorption and scattering of light inside the LED,the performance of white LEDs can be improved.Yeah,LEDs can be made even more efficient and powerful.When in May,2017,researchers who from the University of Twente and Philips Lighting have developed a new method which can lead to efficiency improvement and powerful design tools. They found a detailed way to describe the light that stays inside the LED by absorption and scattering. This is very valuable information for the design process. The Theory about Light Sources From relatively weak light sources to strong lights at home and in cars, for example: since the blue and white LED were invented, we've seen a rapid development in possible applications. Low energy consumption and long lifetime are major advantages over existing lighting solutions. White LEDs consist of a semiconductor emitting blue light, with on top of that phosphor plates that turn the blue light into yellow. What we see then, is white light. The light will be scattered by the phosphor particles, but it is absorbed as well. What part of the light will exit the LED, is not easy to predict. Unless you look at absorption and scattering in another way, according to Maryna Meretska and her colleages. Theory from astronomy helps. Good Prediction is Difficult What makes good prediction particularly difficult: some of the light is absorbed, but re-emitted in another colour. One way is trying to define all possible light rays, and use a lot of computing time to get a result. This doesn't give much insight in what is actually happening. A theory that is often used for light propagation in a LED, is diffusion theory. In strongly absorbing media, however, this approach isn't valid anymore. Meretska therefore has built a setup to collect all the light around the phosphor plates, in the whole visual spectrum. Based on this, absorption and scattering can be deduced using the radiative transfer equation, well known in astronomy.  This results in a full description of light propagation inside and outside the phosphor plates. Compared to a description using diffusion theory, the absorption level is up to 30 percent higher. At the same time, the method is about 17 times faster than the numerical approach. ConclusionThis new insights leaded to powerful and predictive tools for LED designers.They help in further improving the efficiency and overall performance.The research has been done in the Complex Photonic System group of UT's MESA+Institute for Nanotechnology,together with Philips Lighting in Eindhoven. The University of Twente has a strong concentration of research groups and facilities within the rapidly growing field of photonics.  Article provided by University of TwenteArticle edited by kynix 

SummaryChristmas is coming,as well as the New Year's Day. In keeping with the festive lighting of the holiday season,there are various LED lighting architecture in the world. Now let me take you to tour the landmarks lit with LEDs.  In the touring of this LED architecture, I will also introduce how this landmarks be done. Well,these These attention grabbing displays are dependent on products that can deliver a wide range of colors, and a control scheme that allows lighting designers to fully realize their creative ideas. First Stationlet's begin with the glorious Miami in Miami,Florida.  Located downtown, the Miami Tower is a 47-story landmark that you may have seen in films and on television. Before conversion to LEDs, it was lit with a total of 382 1,000 W and 400 W metal halide fixtures, with gels (color filters) applied by maintenance crews to change the color effects. Conversion to a combination of LED flood lighting and strip lighting reduced energy, maintenance, and operating costs by over a quarter million dollars annually, and the building fa?ade can now be changed to a virtually limitless combination of colors and patterns with the “push of a button”. Miami Tower and the other landmarks reviewed in this article are illuminated using Philips Color Kinetics products, which currently have a bit of a monopoly in architectural installations. The control scheme uses a data enabler to combine power with a proprietary Ethernet DMX-based data signal called KiNET, prior to routing to luminaires, junction boxes, and/or strings of strip lights.Over 16 million color combinations can be achieved through the 8-bit channels of Red/Green/Blue/White or Red/Green/Blue/Amber luminaires. A number of different controllers can be used to program either static or dynamic displays. DSP techniques ensure that data corruption is negligible even in noisy, high-EMI environments, e.g., adjacent to powered radio antennas.  Second StationLet's travel across the country to the San Francisco-Oakland Bay Bridge.  The Bay Lights of the San Francisco-Oakland Bay Bridge, installed in 2013 in what was meant to be a two-year run to celebrate the bridge’s 75th anniversary, is currently the largest LED lighting sculpture in the world. With over 25,000 white LED nodes installed on the 1.8 mile western span, the bridge surpasses even the Eiffel Tower in number of LEDs.This lighting system uses light strands,each made up of 50 individually controllable nodes designed to operate in the demanding environment conditons of the bridge--rain,vibration,wind and even road debris. Control software scans the installation to ensure that all lighting is operational Bridge lighting projects are the most challenging to implement according to Philips, because the process can include not just lighting designers, architects, and contractors, but also transportation authorities and the Coast Guard, each with separate concerns and requirements. In addition, lighting installation usually requires workers to hang from suspended cables, and to work at night to minimize traffic impact. Doesn't that sound like fun?  Third StationThis is the season to be shopping,so let's envy the lucky folks in Philadelphia who get to spend time at the appropriately named Lit Brothers Building.  Listed on the National Registry of Historic Places in 1979, the Lit Brothers Building takes up a full city block with its mix of retail and office space. Unlike newer installations, preservation of the historic and structural aspects of the building were paramount in the lighting design, which includes both flood lights and light strips to illuminate the fa-ade and ornamental columns.As engineers, we’re interested in the technical and practical details of these LED projects, like lower operating costs and reduced maintenance requirements, but the non-energy benefits these projects bring can be even more significant. They play a tremendous role in creating a space that local residents and tourists look forward to visiting, enhancing the sense of fun and excitement in the community and the economic boost that often goes with it. Fina Station   The Bai Chay Bridge stands 50 m (164 ft) over Ha Long Bay, one of the most popular and beautiful tourist sites in Vietnam. In 2000, Ha Long Bay was nominated as one of the new seven natural wonders of the world, and in 2004, Ha Long Bay hosted almost 3 million tourists due to its geological value and natural beauty. Scattered across this bay are 1,969 islands, beautiful emerald waters, and with the Bai Chay Bridge, an edition in 2006, a new landmark in Vietnam.The Bai Chay Bridge has the widest width of any cable-stayed, single-plane concrete bridge in the world. The bridge was built to improve traffic conditions and adopt Japanese construction technologies. To make this landmark even more beautiful, the Bai Chay Bridge is now illuminated in colorful LED lights that reflect off the bay waters at night.LED lights were chosen due to their dynamic capabilities, long useful life and energy efficiency. In order to achieve all the goals the investor had set, Philips supplied an environmentally-friendly LED lighting solution for its high efficiency and dynamic and elegant lighting effects.The designers installed ColorReach Powercore gen2 and ColorReach Compact Powercore from Philips Color Kinetics to illuminate the cables and pillars that run high above the bridge, as well as to highlight the dramatic beauty of the bridge’s architecture. ColorGraze MX4 Powercore was used to illuminate the bottom of the bridge, and Archipoint iColor Powercore was used in a direct view application along the spans of the bridge. ConclusionSuch beautiful LED lighting architectures around the world create beauty, enhance entertainment and transform public spaces  for human being and nature. What's more,they witness the LED light's development and become an important milestone in the history of LED lighting.