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The ISL1904 is a high-performance, critical conduction mode (CrCM), flyback controller used for single-stage conversion of the AC mains to a constant current source with power factor correction (PFC). The controller regulates the output current by monitoring the primary side switching current so the feedback signal does not cross the isolation barrier. Operation in CrCM allows near zero-voltage quasi-resonant switching (ZVS) for improved efficiency while maximizing magnetic core utilization. The ISL1904 LED driver provides all of the features required for high-performance dimmable LED ballast designs and supports AC or DC input, isolated or non-isolated flyback and boost topologies. This advanced BiCMOS controller features all of the functions required to design low cost low parts count LED driver.

Key Features

• Excellent LED current regulation over line, load, and temperature
• 0 - 100% dimming with leading-edge (triac) and trailing-edge dimmers
• Power factor correction for up to 0.995 power factor and less than 20% harmonic content
• Critical conduction mode (CrCM) operation for quasi-resonant high efficiency performance
• Supports universal AC mains input
• Configurable for PWM or DC current dimming control of LEDs
• Monitors FET switching current for load regulation
• Supports isolated and non-isolated boost and flyback topologies
• Closed loop soft-start for no overshoot
• OFFREF feature to set dimming off-point to improve fixture performance matching
• -40°C to +125°C operation
• Pb-free (RoHS compliant)

Applications

• Industrial and commercial LED lighting
• Retrofit LED lamps with triac dimming
• Universal AC mains input LED retrofit lamps
• AC or DC Input LED ballasts