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LS7635FO Dataheets PDF



Part Number LS7635FO
Manufacturers LSI Computer Systems
Logo LSI Computer Systems
Description TOUCH CONTROL HALOGEN LAMP DIMMER
Datasheet LS7635FO DatasheetLS7635FO Datasheet (PDF)

LSI/CSI LS7634 LS7635 LS7634FO LS7635FO U® L LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747 (631) 271-0400 FAX (631) 271-0405 A3800 October 2008 TOUCH CONTROL HALOGEN LAMP DIMMER FEATURES: • Touch or pushbutton control of high-voltage lamps and *transformer-coupled low-voltage halogen lamps *Magnetic Transformers and most Electronic Transformers • Automatic Safety Shutdown • Three operating modes • Extension input for remote activation • 50Hz/60Hz AC line frequency • .

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LSI/CSI LS7634 LS7635 LS7634FO LS7635FO U® L LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747 (631) 271-0400 FAX (631) 271-0405 A3800 October 2008 TOUCH CONTROL HALOGEN LAMP DIMMER FEATURES: • Touch or pushbutton control of high-voltage lamps and *transformer-coupled low-voltage halogen lamps *Magnetic Transformers and most Electronic Transformers • Automatic Safety Shutdown • Three operating modes • Extension input for remote activation • 50Hz/60Hz AC line frequency • +5V Power Supply (VDD -VSS) • LS7634, LS7635 (DIP); LS7634-S, LS7635-S (SOIC); LS7634FO, LS7635FO (DIP); LS7634FO-S, LS7635FO-S (SOIC) - See Figure 1 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 LS7634/LS7635 family of CMOS ICs as follows: 1. 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 cause of half-waving. 2. Delayed triac turn-on and safety shutdown With inductive loads, the holding current needed to maintain the triac On-State, may seriously lag behind the gate trigger signal causing the triac to turn off prematurely. If the frequency of occurrences of the delayed turn-on exceeds a preset threshold, a shutdown is initiated by turning off the triac trigger pulses. The safety-shutdown threshold value is accumulated in a 4-bit Up/Down counter. The count increments for every occurrence of delayed turn-on and decrements once every 8 SYNC pulses (AC line cycles). The counter will not decrement below zero. If the count reaches 15, the safety-shut-down is effected. PIN ASSIGNMENT - TOP VIEW LS7634 LS7635 LSI VDD (+V ) 1 MODE 2 TEST 3 SYNC 4 8 TRIG 7 VSS (-V ) 6 EXT 5 SENS FIGURE 1 INPUT/OUTPUT DESCRIPTION: VDD (Pin 1) Supply voltage positive terminal. Vss (Pin 7) Supply voltage negative terminal. MODE (Pin 2) - See Table 1 All variations of LS7634 and LS7635 can operate in 3 different modes. The 3-state MODE input selects the operating modes: Vss = Mode 0; Float = Mode 1; VDD = Mode 2 SYNC (Pin 4) - See Figure 6 The AC line frequency is applied to this input. All internal timings are synchronized to the AC. The Load On/Off status information is also derived from this input. SENS (Pin 5) - See Table 1 A Logic 0 applied to this input alters the TRIG output either by turning it on, turning it off or by changing its conduction an.


LS7634FO LS7635FO MA4AGSW4


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