iWatt has expanded its family of digital LED driver ICs with its first power-factor-corrected (PFC) AC/DC Digital PWM Controller targeting 120V/230VAC offline commercial and industrial LED lighting applications.
 
Like its iW3602 and iW3612 siblings, the new iW3614 (3W – 15W) is designed for LED drivers used in space-constrained incandescent replacement lamps, offers hot-plug support and flicker-free compatibility with existing wall dimmers, and incorporates features to assure power efficiency, durability, and reduced size and component costs.

As iWatt’s first PFC LED driver IC, the iW3614 features a two-stage PFC scheme, on a single chip. A front-stage boost converter enables PF > 0.90 (typically 0.94), while the following PWM driver stage minimizes ripple current at the output.

iWatt believes the advantages of a two-stage over a single-stage PFC design include:
•    Eliminating the low 100Hz/120Hz line frequency ripple and resulting flicker at the output eliminates the health concerns (migraines, eye strain, etc.) that are currently under scrutiny by the IEEE PAR1789.
•    Reducing the output ripple current also enables smaller output capacitors.
•    A small bulk storage capacitor enables a wide (1% to 100%) dimming range, while single-stage designs can limit the range (~ 10% to 100%) without that storage capacitor to power LEDs when the dimmer phase cut is low.
 
iWatt’s digital control, primary side control, quasi-resonant switching and high switching frequency combine to reduce thermal loss, component count, driver size and bill of materials (BOM).