Improved efficiency for CFL lighting

EDN Europe, 08 Nov 2011

The IRS2526DS ‘Mini8’ compact fluorescent lamp (CFL) ballast control IC has full programmability and, according to makers International Rectifier, offers accurate control of all lamp types. It incorporates a 600-V half-bridge control circuit working at 50% duty-cycle and employs variable frequency drive of the resonant mode lamp output circuit. You set the operating frequency of the oscillator via a single analogue-to-frequency input pin, and the circuit provides fault protection against such mains interruption or brown-out, lamp non-strike, or lamp filament failure, and it detects lamp end-of-life. Also included is dithering of internal frequency to reduce conducted EMI, and ignition control to reduce inductor size. IR says that this range of functions has not previously been available in an 8-pin package: IR developed the part as a progression from its IRS2580DS ‘Combo8’ that combines a full featured fluorescent ballast with power factor correction (PFC) controller, also in a compact 8-pin package. Use the new part in applications that do not require PFC or that already have an external PFC controller. In SO8, the chip is rated at an offset voltage of 600V, Vcc of 15.6V and output current of 180 mA.

IR has published a reference design, IRPLMB7E, for a 220VAC/50Hz, 18W TCL lamp featuring the IRS2526DS; using Ballast Design Assistant (BDA) V5.0 design software.