LS7232NT

LSI/CSI UL ® LS7232NT (631) 271-0400 FAX (631) 271-0405 LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747 A3800 PROXIMITY/TOUCH CONTROL HALOGEN LAMP DIMMER FEATURES: Control of incandescent and transformer coupled halogen lamps. No-Touch lamp control through optical sensing PLL synchronization of AC for wall switch application. Extension input for remote control Safety-shutdown for transformer malfunction. Pin-selectable operating modes Single 5V power supply 50Hz/60Hz AC line frequency LS7232NT (DIP), LS7232NT-S (SOIC) - See Figure 1 DESCRIPTION: LS7232NT is a CMOS integrated circuit designed for brightness control of incandescent lamps or tranformer coupled low voltage halogen lamps. The brightness is controlled by controlling the firing angle of a triac in series with the lamp and triggered by the LS7232NT. A Phase-Locked-Loop keeps the LS7232NT phase pointer locked in phase with the line voltage. A unique optical user interface provides for a smooth control of the lamp intensity without the need for touching any sensor plate. A mechanical switch interface for dimming control is also provided which can be used for a remote touch plate. The IC includes features to address problems associated with inductive loads such as transformers in low voltage halogen lamp application. The voltage to current phase lag resulting from the inductance may prevent the triac from shutting off at AC zero crossover and/or prevent the triac from maintain...