LS7339

UL ® LSI/CSI LS7339-7340 (631) 271-0400 FAX (631) 271-0405 June 2001 LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747 A3800 AUTO SHUT-OFF AC POWER SWITCH WITH PROGRAMMABLE TIMER FEATURES: Phase-Lock Loop Synchronization allows use in Wall Switch Applications. PLL accuracy delivers Pure AC Power. Timer programmable with external R-C. ON input switches AC Power On and starts Timer. OFF input switches AC Power Off. 50/60Hz Line Frequency. +12V to +18V Operation (VSS - VDD). LS7339, LS7340 ( DIP) - See Figure 1 LS7339-S, LS7340-S (SOIC) APPLICATIONS: AUTO SHUT-OFF TIMER for appliances such as coffee pots, curling irons, hair curlers, electric blankets, hand dryers. TIMED-ON WALL SWITCH for incandescent lighting and heat lamps. DESCRIPTION: The LS7339 and LS7340 are monolithic MOS integrated circuits designed to turn a triac On and Off in a Power Switch for AC loads. Activation of the ON input will always turn the triac On and start a Timer. The triac remains On for the duration of the Timer which is controlled by an external R-C connected to the OSCILLATOR input. Activation of the OFF input will always turn the triac Off. The two ICs differ only in the width of the TRIG pulse used to trigger the triac. (See I/O Description, Pin 4.) In a typical application (Figure 5), the output of the LS7339 drives the gate of a triac in series with the load. Because the LS7339 is accurately synchronized to the line frequency with a phase-lock loop, t...