RGB LED driver enables multicolour ambient lighting in cars

October 11, 2012 // By Christoph Hammerschmidt
Infineon Technologies has introduced its LINLED driver family for automotive applications. The new TLD73xxEK system-on-chip devices make it possible to implement attractive multicolor ambient lighting based on RGB (Red-Green-Blue) blending to produce a broad range of interior colors with predefined color points. The announcement comes only one week after competitor Elmos has introduced a similar solution.

The integrated LIN transceiver reduces wiring requirements by 25 percent (from 4 to 3 wires), while pre-programmed control of blending and dimming means no additional software development is necessary by the system manufacturer. 

The Infineon TLD73xxEK LINLED driver family includes four different members. They vary by output current (up to 48mA, up to 2A) and LIN compliance according to the LIN 2.1 and SAE J2602 standards. Each family member combines logic, memory, LIN interface and a three channel linear current source or three external driver stages in one device. To achieve predefined color points for multiple RGB modules, the integrated memory stores calibration points for up to 16 colors. 

The use of LEDs that mix red, green and blue emitters allows a theoretically unlimited range of color. The challenge is to achieve predefined colors for each RGB module even as environmental conditions change and accounting for variance between each LED. To compensate these variations, Infineon is among the few semiconductor suppliers offering integrated memory to store pre-calibrated data of up to 16 different color points mixed by the three basic colors. 

The integrated state machine of the TLD73xxEK products enables smooth color transitioning and theater dimming functionality without the need for further software development by the system supplier.

Typically pulse width modulation (PWM) is used to mix the colors, which can cause flickering light output, due to low PWM frequencies. The Infineon TLD73xxEK LINLED driver family uses a proprietary solution for color mixing which allows flicker-free light output as the LEDs are driven with a high frequency signal. 

The TLD73xxEK family is suitable for worldwide use, as it includes members with integrated LIN transceiver fulfilling the LIN 2.1 and SAE J2602 standard. Each device can be programmed with a unique LIN address and different modules can be combined in groups, which react simultaneously on the transmitted LIN message. 

All versions of the TLD73xxEK LINLED family are