EL SEGUNDO, Calif. June 2004 - International Rectifier, IRŪ (NYSE: IRF), a world leader in power management technology, today introduced the IR2520D compact fluorescent lamp (CFL) ballast control IC that can adapt to changing supply voltage, frequency and lamp conditions to increase lamp life and reliability. All necessary ballast features are integrated into a single 8-pin DIP or SOIC, reducing parts count, simplifying circuits and increasing reliability.

"Lighting consumes about 22% of the electricity in the US, according to Rocky Mountain Institute. We can save up to 60% of the electricity flowing to incandescent bulbs by replacing them with CFLs. At IR, we're working hard to advance technologies that can hasten adoption of energy-saving alternatives like CFL. Our exclusive high-voltage junction-isolation (HVJI) IC technology and adaptive control techniques will help make CFLs more reliable and should reduce costs for manufacturers," said David Tam, International Rectifier Vice President, Consumer and Industrial Sector Business.

The IR2520D is a complete ballast controller and 600V half-bridge driver for CFLs. The new device includes a novel zero voltage switching (ZVS) circuit that maintains soft switching, regardless of supply voltage, frequency and lamp conditions, and includes internal crest factor over-current protection and an integrated bootstrap diode. At the heart of this IC is a voltage-controlled oscillator (VCO) with an externally programmable minimum frequency.

Other common compact fluorescent lamp ballasts that use the self-oscillating bipolar transistor solution are very simple, but are not self-starting, and require additional components and circuitry such as DIACs and free-wheeling diodes. In addition, unreliable, "always hot" positive-temperature-coefficient (PTC) thermistors are used for preheat, and they do not have protection against lamp non-strike or open filament conditions. These can give a high susceptibility to component and load tolerances and/or catastrophic failure of ballast output stage components, which can result in poor performance, poor quality and failure.

IR's Enabling HVJI Technology

IR2520D is based upon International Rectifier's high-voltage junction-isolation (HVJI) IC technology. This proprietary technology allows high-voltage circuits to be isolated from low-voltage circuitry, so that both high- and low-side drive functions can be housed on a single, compact chip for controlling various switching converter topologies. Since lighting ballasts require both high- and low-voltage circuits to function, components made with IR's HVJI technology are particularly well-suited to the application.

Adaptive Zero Voltage Switching Control

A key feature of the IR2520D is its adaptive zero voltage switching control. During each half-bridge switching cycle, half-bridge voltage slews to the opposite rail during deadtime. If the voltage has not completely slewed to the opposite rail so that there is zero voltage across the appropriate switch before turn-on, then the operating frequency is too close to resonance and the frequency increases. The built-in adaptive zero voltage switching (ZVS) and zero current switching (ZCS) closed loop control matches operating frequency as close as possible to the half-bridge output stage resonance. Operating a ballast in ZVS/ZCS mode minimizes switching losses in the half-bridge MOSFETs, ensuring maximum efficiency and lifetime, regardless of component and lamp tolerances as well as line voltage variations.

Fault and Protection Modes

The IR2520D features advanced fault and protection circuitry. An open filament lamp fault will cause hard-switching at the half-bridge, and the non-ZVS circuit or the crest factor circuit will detect this condition and will enter fault mode, and both gate driver outputs will be latched low, turning the lamp off.

If a lamp non-strike condition occurs when the filaments are intact but the lamp does not ignite, the lamp voltage and output stage current will increase during the ignition ramp until excessive currents occur or the resonant inductor saturates.

Key specifications for the IR2520D include output drive capability of 250/400mA, 15.6V Zener diode clamp on Vcc, micropower startup current and built-in 30kHz to 125kHz oscillator.

Design Assistance

Click on any of the part numbers below for access to datasheets, reference designs and application notes associated with the IR2520D. In addition, an entire suite of application notes, technical papers, design software and reference designs are available at the IR Lighting website.

Part Number	Package	Standard Pack Quantity	Breakdown Voltage	Drive Current	Junction Temperature
IR2520D	8 Lead DIP	50	600V	250/400mA	-55C to 150C
IR2520DS	8 Lead SOIC	95
IR2520STR	8 Lead SOIC in Tape and Reel	2500

Availability and Pricing

The IR2520D Adaptive CFL IC is available immediately in 8-pin DIP, 8-pin SOIC, or 8-pin SOIC on tape and reel. Pricing for the IR2520D begins at US $0.57 each (IR2520DS) in 100,000-piece quantities.