LS7632

LSI/CSI UL ® LS7631/7632 (631) 271-0400 FAX (631) 271-0405 LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747 A3800 TOUCH CONTROL HALOGEN LAMP DIMMER FEATURES: Touch or pushbutton control of incandescent lamps and transformer-coupled halogen lamps Transformer can be Magnetic or Electronic Direct replacement for P/N SLB 0587 Automatic safety shutdown PLL synchronization allows use as a Wall Switch Three operating modes Extension input for remote activation 50Hz/60Hz AC line frequency +5V Power Supply (VDD - VSS) LS7631, LS7632 (DIP); LS7631-S, LS7632-S (SOIC) APPLICATIONS: Electronic dimmers for wall switch control of ceiling mounted lighting, foot switch control of large floor lamps and hand switch control of table lamps. BACKGROUND AND GENERAL DESCRIPTION: A typical electronic dimmer may not operate properly with the inductive load encountered when driving a transformer-coupled low-voltage halogen lamp. The inductive load can cause a phenomenon called half-waving, wherein the triac fires in alternate half-cycles only, which may lead to the thermal destruction of the load transformer. The problems encountered in driving an inductive load are addressed by the LS7631/LS7632 CMOS ICs as follows: 1. Compensation for delayed triac cut-off. When a trigger pulse is due to occur at a conduction angle which coincides with the on-state of the triac, the trigger pulse is delayed until the triac has turned off. This eliminates the underlying cau...