LS7338

Features:

• Phase-Lock Loop Synchronization allows use in Wall Switch Applications.
• Operation automatically sequences from Timed-On to Delayed-Off to Off.
• On-Timer programmable with external R-C.
• Transition from Timed-On to Delayed Off indicated by 31% drop in Delivered Power.
• Delayed-Off period denoted by Dim-to-Off operation. (See Note 1)
• Control input initiates Operating Sequence and can override Automatic Sequencing.
• 50/60Hz Line Frequency.
• +12V to +18V Operation (V_SS - V_DD).
• LS7338 (DIP); LS7338-S (SOIC) - See Figure 1


Application

• WALL SWITCH for incandescent lighting in garage, corridor, staircase, child's bedroom, teenage study area.
• IN-LINE SWITCH for table lamps.


Pinout




Specifications

PARAMETER	SYMBOL	VALUE	UNIT
DC supply voltage	VSS - VDD	+20	V
Any input voltage	VIN	VSS-20 to VSS + .5	V
Operating temperature	TA	0 to +85
Storage temperature	TSTG	-65 to +150

Description

The LS7338 is a monolithic MOS integrated circuit designed to turn a triac On and Off in a Power Switch for Incandescent Lighting. Activation ofSENSEor SLAVE inputs turns the triac On and starts 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.

When Time-out occurs, the power delivered by the triac is stepped down by 31% and then slowly reduced to Off over a fixed period of time.

In a typical application (Figure 5), the output of the LS7338 drives the gate of a triac in series with the load.

There are three states through which the LS7338 can be stepped.

The states and their corresponding operating mode, phase angles and delivered power levels are shown in Table 1.