Diodes Incorporated (Diodes) introduces the AL58818Q and AL58812Q, a new series of automotive-compliant 18- and 12-channel linear LED drivers designed to provide precise color mixing and brightness control. These devices are ideal for automotive rear lamp modules, grille and emblem lights, and interior ambient lighting. Beyond lighting, other applications include infotainment displays, automotive status indicator lights, touch panels, and LCDs.
The AL58818Q and AL58812Q are designed to simplify the creation of complex and animated LED lighting modules, enabling vivid lighting effects with zero audible noise. Each channel features an internal 12-bit pulse width modulation (PWM) generator operating at 30kHz for fine-tuned color mixing and brightness control. System designers can select between I2C or SPI digital interfaces through a hardware-selectable pin, providing enhanced programming flexibility.
The AL58818Q has 18 channels, making it ideal for up to six RGB LED lighting modules or 18 single-color LEDs, while the AL58812Q provides 12 channels for up to four RGB LED modules. Each channel delivers up to 70mA of current set by the external resistor. The maximum global 6-bit output current for all channels is adjustable through registers. Each channel also has an internal 30kHz, 12-bit PWM generator for smooth dimming regardless of programming registers through the digital interface (I2C or SPI).
The devices feature independent color-mixing registers and brightness control registers per RGB LED module, enabling over 16 million (256 x 256 x 256) color combinations. They support both logarithmic and linear-scale brightness control for human-eye-friendly visual performance, with a default 12-bit PWM resolution achieved through 9 bits of pure PWM and 3 bits of dithering digital control. The 3-bit dithering scheme enhances PWM resolution to 0.0244%. Furthermore, deep dimming is supported, where the internal circuitry converts the PWM signal to analog dimming when the duty cycle falls below 3%, maintaining overall linearity.
Both devices boast an accurate 3% device-to-device and channel-to-channel current matching, which ensures precise color mixing and uniform color distribution across various lighting modules and displays. An internal 16MHz oscillator eliminates the need for an external PWM clock, reducing bill-of-materials (BOM) costs. PWM phase-shifting is implemented to delay the activation time of individual LED drivers, significantly decreasing the peak load current from the power supply and reducing input-current ripple and audible ringing from ceramic capacitors.
For animation effects like blinking and breathing, the AL58818Q and AL58812Q offer LED bank control, allowing channels to be configured for either independent or bank-controlled operation. This simplifies software effort for global LED effects.
The devices each feature an open-drain FAULT indication pin and registers to report issues such as LED open/short circuits, undervoltage lockout (UVLO), pre-UVLO warning, overtemperature protection (OTP), and pre-OTP warning. Individual fault mask registers allow designers to enable or disable fault reporting for specific channels.
The AL58818Q and AL58812Q support an ultra-low quiescent shutdown current of 1µA. They automatically enter a power-saving mode, consuming a maximum of 15µA, when all LED outputs are inactive for more than 30ms.
Both parts are offered in the W-QFN5050-40/SWP (Type A1) package with wettable flanks to aid in automated optical inspection, ensuring good solderability. Complementing these devices is the previously released 36-channel AL5887Q, which has the same feature set.
Design tools for these devices include the RGB 3-in-1 evaluation board, which features an on-board MCU.
The AL58818Q and AL58812Q are available at $0.85 and $0.80, respectively, in 5,000-piece quantities. Standard compliance versions, AL58818 and AL58812, are available and are suitable for industrial and commercial applications.
