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Full-Featured, Dimmable AC Mains LED Driver with PFC

ISL1902

The ISL1902 is a high-performance, critical conduction mode

(CrCM), single-ended controller used for single-stage

conversion of the AC mains to a constant current source with

power factor correction (PFC). This controller may be used in

virtually any single-ended topology, isolated or non-isolated,

including Boost, SEPIC, Flyback, and Forward converters.

Operation in CrCM allows near zero-voltage switching (ZVS) for

improved efficiency while maximizing magnetic core

utilization.

The ISL1902 is compatible with both leading and trailing edge

modulated AC mains dimmers as well as analog signal and

ambient light sensor controlled dimming methods. The LED

string may be dimmed either by modulation of the DC current

or PWM dimming. In-rush current limiting minimizes current

spikes caused by leading edge dimmers and prevents dimmer

malfunction when one or more LED fixtures are connected.

Two control loops are provided to improve transient response

since one loop must have restricted bandwidth to allow PFC.

The second control loop may be configured for higher

bandwidth to respond to input transients quickly and prevent

them from propagating to the load and appearing as

flashing/flickering.

The ISL1902 LED driver controller provides all of the features

required for high-performance dimmable LED ballast designs.

Applications

• Industrial and commercial LED lighting

• Architectural lighting LED drivers

• AC or DC input LED ballasts

Features

• Excellent LED current regulation over line, load, and

temperature

• 0 - 100% dimming with leading-edge (triac) and

trailing-edge dimmers

• Analog control signal dimming

• Configurable for PWM or DC Current Dimming Control of

LEDs

• Dual control loops for PFC and fast transient response

• Compatible with ambient light sensors for uniform

lamp-to-lamp performance

• 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

• Active pre-load to eliminate power-off “afterglow”

• OFFREF feature sets dimming turn-off-threshold to improve

fixture performance matching

• In-rush protection control for each AC half-cycle minimizes

audible noise and eliminates dimmer resonance

• Input or Output Overvoltage Protection (OVP)

• Over-Temperature Protection (OTP)

• Bias Supply Under Voltage Lockout (UVLO)

• -40°C to +125°C operation

• Pb-free (RoHS compliant)

FIGURE 1. TYPICAL APPLICATION - DIMMING PERFORMANCE

FIGURE 2. TYPICAL APPLICATION - POWER FACTOR

0

100

200

300

400

500

600

700

800

0

20

40

60

80

100

AC CONDUCTION ANGLE (%)

0.90

0.92

0.94

0.96

0.98

1.00

80

130

180

230

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

1-888-INTERSIL or 1-888-468-3774

Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.

All other trademarks mentioned are the property of their respective owners.

March 20, 2013

FN7981.2