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LS7538 Datasheet(PDF) 1 Page - LSI Computer Systems

Part No. LS7538
Description  TOUCH CONTROL STEP DIMMER LIGHT SWITCH WITH AUTOMATIC GAIN CONTROL (AGC)
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Maker  LSI [LSI Computer Systems]
Homepage  http://www.lsicsi.com
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LS7538 Datasheet(HTML) 1 Page - LSI Computer Systems

   
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TOUCH CONTROL STEP DIMMER LIGHT SWITCH
WITH AUTOMATIC GAIN CONTROL (AGC)
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
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 (LS7539 only).
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.
TABLE 1. BRIGHTNESS STEP MODES
MODE PIN
BRIGHTNESS STEP SEQUENCE
FLOAT
OFF-NIGHT LIGHT-MEDIUM-MAXIMUM-OFF
VDD
OFF-NIGHT LIGHT- LOW MEDIUM-HIGH MEDIUM-MAXIMUM-OFF
Vss (LS7538)
OFF-MAXIMUM-MEDIUM-NIGHT LIGHT-OFF
(LS7539)
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.
PIN ASSIGNMENT
TOP VIEW
1
2
3
4
8
7
6
5
FIGURE 1
TRIG
VDD(+V
)
MODE
CONTROL
V SS(-V)
SYNC
CLOCK
TOUCH
December 2002
7538/39-120202-1
TABLE 2. BRIGHTNESS POWER LEVELS
Brightness
60Hz Delay (1)
50Hz Delay (2)
% PWR (3)
Night Light
6.0 ms
7.2 ms
12
Low Medium
4.8 ms
5.7 ms
35
Medium
4.0 ms
4.8 ms
53
High Medium
3.2 ms
3.8 ms
72
Maximum
0.85 ms
1.0 ms
99
(1) With 300k
Ω connected between Pin 1 and VDD.
(2) With 360k
Ω connected between Pin 1 and VDD.
(3) Percentage of Full Power delivered to a resistive load by the Triac Switch.
LSI/CSI
LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747
(631) 271-0400 FAX (631) 271-0405
LS7538-LS7539
UL
®
A3800


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