LS7237 Datasheet | LSI Computer Systems

FEATURES : - PLL synchronization allows use as a Wall Switch - Provides brightness control of an incandescent lamp with a touch plate or mechanical switch - Can control speed of shaded pole and universal AC motors - Controls the "duty cycle" from 23% to 88% (conduction angles for AC half-cycles between 45˚ and 158˚, respectively) - Operates at 50Hz/60Hz line frequency - Extension input for remote activation - +12V to +18V DC Power Supply (VSS - VDD) - 8-Pin Plastic DIP , 8-Pin SOIC-See Figure 1 PIN ASSIGNMENT - TOP VIEW V SS (+V) TRIG MODE V DD (-V) DESCRIPTION : LS7237 is a monolithic, MOS integrated circuit designed to control the brightness of an incandescent lamp. The output of the LS7237 triggers a triac connected in series with a lamp(See Figure 5). The lamp brightness is determined by controlling the output conduction angle (triac triggering angle) in relation to the AC line frequency (See Figure 2). The output conduction angle can be varied by applying a low level pulse at the SENS input or a high level pulse at the EXT input. When implemented as shown in Figure 5, this is acplished by touching the Touch Plate which causes the lamp brightness to change in specified steps as follows: LEVEL Off Night Light Mood Light Medium Maximum BRIGHTNESS (% Rated Wattage) 0 9 29 66 99 SYNC SENS FIGURE 1 INPUT/OUTPUT DESCRIPTION : VSS (Pin 1) Supply voltage positive terminal. MODE (Pin 2) The operating mode for the circuit is selected by connecting this input as follows: MODE INPUT VSS VDD Float SELECTED MODE Mode 0 Mode 1 Mode 2 The LS7237 can operate in one of three different modes selected by the MODE input. The Brightness Sequences produced by the different modes are as follows: MODE 0 1 2 BRIGHTNESS SEQUENCE Off-Max-Off Off-Mood-Med-Max-Off Off-Night-Mood-Med-Max-Off CAP (Pin 3) PLL filter input capacitor. A 0.047µF capacitor should be connected to this input. SYNC (Pin 4) The AC Line Frequency is applied to this...