LS7538

Features:

• Touch Sensitivity guaranteed to 600pF Touch Plate Capacitance.
• Touch Operation independent of line plug polarity.
• Pin selection of three available Brightness Step Sequences.
• Minimal external components.
• AGC Loop stabilizes immediately after Power-Up.
• Brightness state is Off after AC power applied.
• Brightness state is unchanged if AC power interrupted for < 0.5 sec.
• Advanced CMOS design for reliable operating characteristics and low power.
• 50/60 Hz Line Frequency.
• +6V to +9.5V Operation (VDD-VSS).
• LS7538, LS7539 (DIP); LS7538-S, LS7539-S (SOIC) - See Figure 1


Application

• 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 (LS7539 only).


Pinout




Specifications

PARAMETER	SYMBOL	VALUE	UNITS
DC Supply Voltage	Vdd-VSS	+11	V
Voltage at any input	VIN	VSS -0.5 to Vdd + 0.5	V
Operating temperature	TA	-20 to +85	°C
Storage temperature	TSTG	-65 to +150	°C

Description

The LS7538 and LS7539 are CMOS integrated circuits which provide 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.