International Rectifier Corp. (IR) has introduced a single-chip fluorescent lamp ballast device with an active, critical conduction mode, boost-type power factor correction (PFC) method. The IR2167 controls the entire electronic ballast, and combines lamp control, power factor correction and a 600V half-bridge driver. Ballast functions include control for preheating, igniting and powering a fluorescent lamp, and protection against such lamp failures such as open filament, lamp non-strike, brown-out, below resonance and end-of-life.
The control method for power factor correction eliminates the need for a multiplier or an external current sensing resistor by using fixed on-time control. Fixed on-time control, however, is not enough to achieve high power factor and low harmonic distortion at the mains input voltage. An additional modulation of the on-time decreases cross-over distortion of the line current and therefore reduces the total harmonic distortion (THD) at the same time.
The ballast control section in the IR2167 incorporates a programmable oscillator, which enables all ballast operating frequencies and MOSFET driver output deadtime. The lamp protection circuitry shuts down when any external lamp fault condition is detected.
The IR2167 is designed to simplify PFC ballast circuits and improve efficiency while maximizing lamp life. The IR2167 enables ballast designs with power factors of 0.99, and THD lower than 10%, well within the IEC 6100-3-2 standards.
A soft-start function makes the IC run at very high frequency to prevent flashing at lamp start and high voltage conditions that can ruin a lamp. The end-of-life protection function detects wear in the lamp filament by sensing voltage shift and shuts the lamp down when it exceeds preset limits. This eliminates the risk of exposing the filament to excessive voltage, which can melt the lamp glass and become a fire or safety hazard.
Tom Ribarich, Director, Lighting Design Center at IR, said, "The IR2167 is maximized for high-end, indoor lighting ballasts where power factor correction at the mains input is required by law. The same ballast architecture can also be applied to high-intensity discharge (HID) outdoor applications, such as street, gas station and retail store lighting."
The new IR2167 is available immediately. Pricing for the IR2167S (20-pin DIP) is US $2.38 each, while the IR2167 (20-pin SOIC) is US $2.68 each in 10,000-unit quantities.
