Industrial Electronics

LED Drivers Deliver Flicker-Free Dimming of Tunable White and Color LEDs

09 September 2015

Diodes Incorporated has introduced the AL1791/2/3/4 LED drivers that are single to quad-channel DC to constant current (DC-CC) LED driver ICs, providing both analog and pulse-width modulation (PWM) dimming control. Used with an AC-DC power conversion block and an MCU, the current-ratio-optimized regulators yield scalability, ease of implementation and a cost-effective solution.

Featuring a 6.5 V to 30 V input voltage range, the regulators drive up to four independent LED channels with a maximum of 500 mA per channel or 1.5 A total drive current for the AL1792/3/4, or 1A maximum for the AL1791. Each channel is controllable down to 0.125% with 500 Hz to 10 kHz flicker-free PWN dimming, or with analog dimming down to 1.25%.

While a human eye notices flicker at 120 Hz, the ability to operate PWM dimming above 1 kHz avoids problems with e-Flicker picked up by smart-phone cameras that produce dark bands on still images. The AL179X is capable of high frequency PWM for deep dimming applications; 10 KHz at 1.0%, 4 KHz at 0.4% and 1 KHz at 0.1%.

The AL179X LED drivers feature an enable pin for low standby power, internal protection for LED string open/short-circuit and under voltage lockout, over-temperature protection with thermal shutdown and auto-recovery, and full fault reporting and LED power-good reporting. An integrated low-side current sink topology allows for either lower cost common-anode LED connections or different anode voltages for improved energy-efficiency. All devices are packed in a 14-pin UDFN-4030 package.

Unit pricing in 1k piece quantities is from $0.64 for the single-channel AL1791AFE-13. For evaluation purposes, the AL1794EV1 evaluation board is available on request.

Related Links:

Single/Dual/Triple/Quad-Channel Current-Ratio-Optimized LED Driver with Analog and PWM Dimming

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