OSRAM OSIRE^® E3731i is an innovative fusion product of automotive-grade RGB LED and microcontroller. Catering to the trend of RGB ambient lighting in automotive interiors, the LED part inherits the outstanding performance and high reliability of the OSIRE series, and the microcontroller IC is fully automotive-qualified, developed over many years with a carefully designed communication protocol, which greatly facilitates color calibration and temperature compensation in the application of automotive interior ambient lighting. The simplified electronic architecture makes it possible for dynamic ultra-thin light strips (6mm wide) and matrix displays, especially advantageous in applications with many RGBs.

1，Technical parameters and performance

• Each channel of the RGB LED has two current levels of 10mA and 50mA. At 50mA, the brightness can reach 2500mcd for red, 4300mcd for green, and 800mcd for blue.
• The microcontroller consists of a control unit, a bidirectional communication unit, PWM drivers, memory, a temperature sensor, and a bidirectional communication controller.
• The three PWM drivers have an output capability of up to 15 bits and up to 1000Hz, with short-circuit and open circuit detection;
• The memory contains the RGB color brightness information of each E3731i at 10mA and 50mA;
• The temperature sensor allows the MCU to directly read the temperature of each E3731i with an accuracy of up to 8 bits.
• The communication unit includes two sets of differential signals on the left and right, all with bidirectional communication capabilities.

2，Features and Advantages
• No Need for Re-color Calibration:
During the production phase, we calibrate the color brightness information of each OSIRE^® E3731i and store it in the embedded memory on the LED chip. With this data, car manufacturers can more easily perform end-calibration of interior lighting, ensuring that each OSIRE^® E3731i in the entire system of hundreds of ambient lights exhibits extremely high optical consistency and uniformity.

• Open Protocol:
Each LED with an integrated IC possesses intelligent functions and can achieve efficient communication with the microcontroller through the SPI interface. At the same time, ams OSRAM also provides an open communication protocol (OSP) for the OSIRE^® E3731i product. With OSP, the microcontroller can send instructions to and receive status from each OSIRE^® E3731i, achieving high-precision color calibration and temperature compensation. Any car, LED, lighting system, or microcontroller manufacturer can use OSP without authorization and completely free of charge.

• More Stringent Automotive Grade Certification:
The interior RGB ambient lighting of the OSIRE series complies with the automotive grade certification AECQ102. As the latest fusion product of LED + IC, AEC has specially formulated the specification AEC-Q102-003 for the fusion chip, with more comprehensive and extensive test coverage than the separate Q100 and Q102. In addition, OSIRE^® E3731i also plans to support products with anti-sulfurization grade 3B for automotive exteriors in the future, as well as versions supporting the IMSE in-mold structural electronics process.


3，Application Samples

Sample 1：By using OSP protocol, OSIRE^® E3731i can connect up to 1000 ambient lights in the vehicle with a single control chain from an MCU, without the need for additional LED drivers. In application, the large number of smart RGB LEDs can achieve dynamic lighting effects, including pulse effects, breathing effects, or rapid color/brightness switching, and even synchronize with the rhythm of music.
Sample 2： The use of OSIRE^® E3731i can reduce the number of components, simplify the system architecture, and decrease wiring complexity. It enables the realization of applications that are demanding in terms of size, such as light strips with a width of only 6mm, flexible PCB light strips, and RGB matrix arrays. These applications, which were previously unattainable, are gradually becoming mainstream and are favored by many customers.


4，Prospect

Ambient lighting in automotive interiors, as a part of the future smart cockpit, requires many RGB LEDs for dynamic atmospheres, user interaction experiences, and smart surfaces. The introduction of OSIRE^® E3731i is in response to the trend of systems that are easy to implement and respond quickly, with uniform color and brightness that is not affected by temperature changes.
The new Open System Protocol (OSP) acts as a "universal language," enabling compatible devices such as LEDs, microcontrollers, and sensors to communicate via standard serial buses. OSP is available for free use by any manufacturer, which will help to create a vibrant ecosystem of products and suppliers, aiding automotive manufacturers in realizing their future vision for ambient lighting.