LS7234
Key Features
- Phase-lock loop synchronization allows use in Wall Switch applications.
- Provides brightness control of incandescent lamps with touch plates or mechanical switches.
- Controls the "duty cycle" from 23% to 88% (conduction angles for AC half-cycles between 41˚ and 158˚, respectively.)
- Operates at 50Hz/60Hz line frequency.
- Extension input for remote activation.
- Input for slow dimming.
- +12V to +18V DC Power Supply voltage. (VSS - VDD)
- LS7231 to LS7234 (DIP) - See Figure 1 LS7231-S to LS7234-S (SOIC) DESCRIPTION: LS7231 through LS7234 are a series of monolithic, MOS integrated circuits designed for the control of brightness of incandescent lamps. The outputs of these ICs control the brightness of a lamp by controlling the firing angle of a triac connected in series with the lamp. All internal timings are synchronized with the line frequency by means of a built-in phase-lock loop circuit. The output occurs once every half-cycle of the line frequency. Within the halfcycle, the output can be positioned anywhere between 158˚conduction angle for maximum brightness and 41˚ conduction angle for minimum brightness in relation to the AC line frequency. The positioning of the output is controlled by applying a low level at the SENS input or a high level at the EXT input. These functions may be implemented with very few interface components, as shown in Figure
- When implemented in this manner, touching of the Touch Plate causes the lamp brightness to change as follows:
- If the Touch Plate is touched momentarily (42ms to 333ms), the lamp is: a) turned off if it was on, b) turned on if it was off. The brightness resulting is either full brightness or depending on the circuit type, a previous brightness stored in the IC memory.
