Cost-effective RGB LED driver solution

One of the fastest growing areas of LED application is effect lighting, also known as architectural lighting. Effect lighting can use RGB LEDs, which use three chips, each responsible for generating one color of light (red, green and blue). Another way to generate different colors of light is to use red, green and blue single-color LEDs and then mix the light from these LEDs. Infineon offers LED drivers for low-power, medium-power and high-power LEDs (Figure 1), as well as microcontrollers for controlling the color of LED modules.

For low-power RGB LEDs, the extremely low-cost BCR40x high-side linear LED drivers can be used. The color of the LED light can be controlled using PWM signals generated by the microcontroller. For medium-power (0.5W) RGB LEDs or single-color LEDs, the new low-side LED drivers BCR321U and BCR421U are the best choice. The BCR321U can regulate currents up to 250mA. Both driver models have a direct logic level input that can be directly controlled by a microcontroller.

Figure 1: Infineon Technologies offers LED drivers for low-power, mid-power and high-power LEDs.
Figure captions:
LED drivers for general lighting and industrial applications: LED drivers for general lighting and industrial applications; Supply voltage: Supply voltage; Ext. transistor: External transistor; Ext. MOSFET: External MOSFET; LED drivers for low power LED: LED drivers for low power LEDs; LED drivers for high power LED: LED drivers for high power LEDs; LED drivers for 0.5W LED: LED drivers for 0.5W LEDs; Offline LED driving solutions: Offline LED driving solutions

All BCR-type LED drivers have a negative thermal coefficient, which means that the current will drop at a rate of 0.2%/K when the temperature rises. LED drivers such as BCR321U, BCR421U and BCR40xU all use a very small SC-74 package (2.9x2.5x1.1mm) and have a power consumption of 1W. The application circuit diagram is shown in Figure 2. LED driver BCR40xW uses an even smaller SOT343 package. Applications for BCR 320U/420U include: architectural LED lighting; advertising channel letters; decorative lighting LED strips; refrigerator and freezer trade lighting; emergency lighting (step lighting, exit signs, etc.); interior lighting for ships, trains and aircraft.

For low-power LEDs (and sometimes medium-power LEDs), the common method is still bias resistors. This method has major disadvantages, such as uneven light emission and shortened LED life. As an alternative, switch-mode drivers cannot meet the price requirements of 0.5W LED products and the drive circuit is relatively complex.

Figure 2: Low cost LED drivers for medium power LED application circuit.
Figure Note:
Low cost LED drivers for medium power LED: Low cost LED drivers for medium power LED;
Application example: Application example;
Optional: Optional

The new BCR321 and BCR421 LED drivers are tailored to overcome the shortcomings of 0.5W LED applications. The proven BCR40x LED driver portfolio is ideal for 0.1W LED applications. All versions of the LED driver offer extremely low cost, simplified solutions and small form factors.

For high-power LEDs, switch-mode drivers are the most commonly used LED drivers. Infineon launches the new ILD4xxx step-down converters for driving high-power LEDs. The ILD4035 with a typical output current of 350mA is specifically designed to drive 1W LEDs. For LEDs above 3W, Infineon launches the ILD4120 and ILD4180 with output currents of 1200mA and 1800mA respectively.

In addition to high efficiency and features such as overvoltage and overcurrent protection, all ILD versions also feature thermal protection. When the junction temperature reaches 125°C, the output current is significantly reduced, ensuring a long LED lifetime. The ILD4001 is an LED controller that can be used in conjunction with a high-current external MOSFET (700mA to several amps). Both the ILD4035 and ILD4001 are available in a small SC4 package.

Infineon Technologies has launched a microcontroller for lighting applications. In addition to controlling multi-channel LED lamps or modules, the microcontroller can also bring more value to the lighting system, such as dimming, lamp temperature control, and connection to the lighting network. Connection to the lighting network ensures the realization of functions such as daylight adjustment, motion control switching, unified remote control, HMI interface, maintenance monitoring, and lamp verification.

Infineon's XC800 microcontroller family includes a variety of products that can bring rich features to the lighting system (Figure 3). The main features of these lighting application products are: 48MHz capture and compare unit (CCU6) generates 4 PWM control signals, and realizes direct hardware connection with 10-bit analog-to-digital converters (up to 8 channels); serial communication I/F includes UART, SPI, I2C; power-down mode results in a typical power consumption of only 2μA; DALI slave protocol stack; long service life, and the product is optimized for high temperature resistance.

Figure 3: Infineon's XC800 microcontroller family includes a variety of products that can bring rich features to lighting systems.
Figure Note: XC800 8-bit MCU family: XC800 8-bit microcontroller family; Flash: Flash memory;

In addition to products for fast and precise control of multi-channel LEDs, Infineon also offers the XC82x and XC83x product families. Devices in these two families feature HMI interfaces such as inductive touch wheels by integrating capacitive touch controllers, such as the new XC822T.

In addition to microcontrollers, Infineon also offers a variety of development tools to accelerate hardware and software development, from USB entry-level tool kits that ensure rapid evaluation of key features such as ACD and CCU6 to simple kits that configure microcontroller pins, all with a complete tool chain. With the new XC82x and XC83x families, Infineon will be able to launch a new free Eclipse-based tool chain DAVE Bench. Application kits for lighting solutions are currently being developed to showcase the entire solution, including microcontrollers, power semiconductors and software.