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| | | International iôr Rectifier | | |
| | | APPLICATION NOTE | | |
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| | | Application Note AN-1019 | | |
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| | | IR21571: Dual Lamp Ballast: Parallel Configuration By T. Ribarich, E. Thompson, A. Mathur, International Rectifier | | |
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| | | Table of Contents Page | | |
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| | | Introduction..........................................................................................1 Functional Description (Variation I)......................................................1 Schematic Diagram (Variation I)..........................................................3 Measurements (Variation I)..................................................................4 Bill of Materials (Variation I).................................................................6 Functional Description (Variation II).....................................................7 Schematic Diagram (Variation II).........................................................8 Bill of Materials (Variation II)................................................................9 | | |
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| | | Driving two lamps in parallel results in lower voltage stress on the ballast output stage components, the wiring, and the fixture sockets. Additionally, the resonant L and C associated with the lamps will be less sensitive to component tolerances due to the lower running lamp voltages compared to the series configuration. For these reasons, the parallel configuration is becoming more popular. The IR21571 can be used in a ballast to control parallel lamp configurations. Through externally programmable components, the IR21571 affords flexibility of various features such as preheat time and frequency, ignition ramp characteristics, and running mode operating frequency. Comprehensive protection features protect the circuit against conditions such as lamp strike failures, filament failures, low DC bus, thermal overload, and ramp failure during normal operation. Two variations of this circuit are included in this application note. The first one switches off both lamps when one is taken out, and automatically restarts when both lamps are in place. The second variation allows one lamp to remain running when the other is removed. When the lamp is reinserted, the ballast restarts in the pre-heat mode. | | |
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| | | AN-1019 | | |
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