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.

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