LS7541 Datasheet | LSI

FEATURES : - - - - - - - - - - - PIN ASSIGNMENT TOP VIEW CLOCK TRIG SYNC V SS (-V ) V DD (+V ) MODE APPLICATIONS: - Screw-in and built-in adapter modules for converting table and floor lamps to touch control for step dimming. - On-Off touch control of under-cabinet fluorescent lamps. TOUCH CONTROL FIGURE 1 DESCRIPTION : The LS7541 is a CMOS integrated circuit which provides trigger pulses for triac phase control of incandescent lamps. The circuits are designed to operate with a wide variety of lamp sizes ranging from small table lamps to large floor lamps. The AGC Loop automatically adjusts Touch Sensitivity to be independent of lamp size. There are 3 different Brightness Step Sequences for each version of the IC which can be selected by the Three-State MODE pin as shown in Table 1. TABLE 1. BRIGHTNESS STEP MODES MODE PIN FLOAT VDD Vss BRIGHTNESS STEP SEQUENCE OFF-NIGHT LIGHT-MEDIUM-MAXIMUM-OFF OFF-NIGHT LIGHT- LOW MEDIUM-HIGH MEDIUM-MAXIMUM-OFF OFF-MAXIMUM-OFF The lamp brightness is made to vary by changing the delay of the TRIG pulse to the triac from the zero-crossing of the SYNC input. The delays are shown in Table 2 for 50Hz and 60Hz operation along with Delivered Power as a percentage of Full Power. Figure 2 illustrates the delay. TABLE 2. BRIGHTNESS POWER LEVELS Brightness Night Light Low Medium Medium High Medium Maximum 60Hz Delay (1) 6.0 ms 4.8 ms 4.0 ms 3.2 ms 0.85 ms 50Hz Delay (2) 7.2 ms 5.7 ms 4.8 ms 3.8 ms 1.0 ms % PWR (3) 12 35 53 72 99 (2) With 470kΩ connected between Pin 1 and VDD. (1) With 400kΩ connected between Pin 1 and VDD. (3) Percentage of Full Power delivered to a resistive load by the Triac Switch. 7541-051106-1 FIGURE 2. OUTPUT DELAY (Td) SYNC (Pin 2) TRIG(Pin...