Multi-channel LED driver addresses RGB and single colour solid state lighting
A linear current LED driver, the AL5887, offers a simple way of driving numerous LEDs to enable complex colour mixing and different lighting patterns, said Diodes. It integrates two interface options (I2C and SPI) for system design flexibility. It delivers a wide colour range and an extensive dynamic range of brightness levels, making it suitable for use in smart home appliances, electric vehicle charging stations, infotainment displays, IoT information indicators, and computing hardware.
The AL5887 has 36 independent programmable channels and can drive up to 12 RGB LED modules or 36 single-colour emitters. It features an internal 12-bit pulse-width modulation (PWM) for colour and 6-bit analogue brightness control, which can be accessed through either the SPI or I2C interface.
There are three programmable banks for software control of each colour for ease of programming and setting lighting module patterns. An independent colour-mixing and brightness register per channel enables better colour-mixing schemes, said Diodes. The dimming function relies on a PWM duty cycle from three to 100 per cent. Once the duty cycle goes below three per cent, internal circuitry converts the output to analogue dimming, maintaining linearity. By combining PWM and analogue dimming functions, a dimming ratio greater than 100K to 1 can be achieved.
The AL5887’s diagnostics with fault-reporting functions are combined with built-in protection capabilities, which include short-circuit and open-LED protection, as well as over-temperature shutdown. The pre-event over-temperature shutdown warning also results in earlier system protection.
Using the two external hardware address pins, up to four of these devices can be connected together in I2C mode. An internal 16MHz oscillator avoids the need for an external high-precision clock and therefore reduces the bill of materials (BoM) cost.
The AL5887 LED driver is supplied in a 52-pin wettable QFN package, with exposed pad for better heat dissipation.