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