Diodes Incorporated – LED driver ICs ensure flicker-free dimming of tunable white lighting

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The AL179x series of LED driver ICs from Diodes Incorporated are aimed at smart and connected lighting applications that use tunable white and colour LED bulbs.

The AL1791, AL1792, AL1793 and AL1794 are single-, dual-, triple- and quad-channel constant-current regulators which offer both analogue and PWM dimming control. When combined with an AC-DC power-conversion block and a microcontroller, these current ratio-optimised regulators provide a cost-effective, scalable and easy-to-implement solution for smart lighting designs.

Operating from a 6.5V to 30V input-voltage range, the AL1792/93/94 regulators can provide a maximum of 500mA per channel or 1.5A total drive current. The AL1791 can provide a maximum of 1A through its single channel.

Each channel can be individually controlled down to 0.1% of peak current with flicker-free PWM dimming operating at frequencies from 500Hz to 10kHz. Using analogue dimming, the devices can dim down to 1.25% of peak current.

Support for deep dimming to below 1% is important because the human eye perceives light intensity as the square root of the measured light, which is proportional to the dimming current.

Similarly, while the human eye only notices flicker at frequencies below 120Hz, the ability to dim at PWM frequencies above 1kHz avoids problems with e-flicker: this is the flicker rendered by cameras such as those in smartphones as dark bands on still images.

The AL179x regulators are capable of high- frequency PWM operation even for deep dimming: 10kHz at 1.0%, 4kHz at 0.4% and 1kHz at 0.1%.

FEATURES

  • Enable pin provides for low stand-by power
  • Under-voltage lock-out
  • Open/short protection of LED string
  • Over-temperature protection
  • Fault reporting
  • LED Power Good reporting
  • Ambient-temperature range: -40°C to 105°C

APPLICATIONS

  • Colour-tunable LED light bulbs
  • Tunable white LED light bulbs
  • Dimmable LED light bulbs
  • LED power supplies
  • Smart lighting
  • DC-DC power conversion
  • LED drivers

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Orderable Part Number: AL1794EV1

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