Single-ended buck LED driver controllers reduce cost, maximize efficiency

January 31, 2013 // By Christoph Hammerschmidt
Intersil Corp. has introduced two new LED driver controllers that not only operate in critical conduction mode (CrCM) but also deliver the industry's highest efficiency and dimming performance in industrial and commercial lighting systems.

The ISL1903 and ISL1904 are high-performance; single-ended buck and flyback LED driver controllers that support single-stage conversion of the AC mains to a constant current source with power factor correction (PFC). Designed for isolated and non-isolated power applications, the ISL1903 supports buck converter topologies including isolated forward converters and non-isolated source return buck converters. The ISL1904 supports isolated flyback as well as non-isolated SEPIC and Boost topologies. They operate in CrCM to allow near zero-voltage switching, maximizing both efficiency and magnetic core utilization. Both the ISL1903 and ISL1904 may also be used with DC input sources.

Both devices deliver near-universal dimmer compatibility, and are designed for industrial and commercial lighting installations and retrofits. Additionally, they can be used in DC or AC input LED ballasts and in universal AC mains input LED retrofit lamps.

Features and Specifications

  • Configurable for either PWM or DC current dimming control of LEDs
  • Compatible with leading and trailing edge dimmers
  • Zero to 100 percent dimming capability
  • Corrected power factor of 0.995 enables Energy Star rating
  • Less than 20% harmonic content
  • Closed loop soft-start assures no overshoot
  • Primary side current sensing eliminates the need for opto-couplers, lowering BOM cost
  • -40° to +125°C operation

The ISL1903 and ISL1904 are available now in compact 16-lead QSOP packages, with prices starting at $0.84 each in 1,000-unit quantities.