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LS7540 参数 Datasheet PDF下载

LS7540图片预览
型号: LS7540
PDF下载: 下载PDF文件 查看货源
内容描述: TOUCH CONTROL连续调光器具有自动增益控制( AGC ) [TOUCH CONTROL CONTINUOUS DIMMER with AUTOMATIC GAIN CONTROL (AGC)]
分类和应用:
文件页数/大小: 5 页 / 60 K
品牌: LSI [ LSI COMPUTER SYSTEMS ]
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LSI/CSI
UL
®
LS7540
(631) 271-0400 FAX (631) 271-0405
LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747
A3800
TOUCH CONTROL CONTINUOUS DIMMER with
AUTOMATIC GAIN CONTROL (AGC)
June 2006
FEATURES:
• Touch or pushbutton control of incandescent lamps.
• Touch Sensitivity guaranteed to 600pF Touch Plate Capacitance.
• Touch Operation independent of line plug polarity.
• Minimal external components.
• AGC Loop stabilizes immediately after Power-Up.
• Brightness state is Off after AC power applied.
• No change of Brightness state if AC power interrupted < 0.5 sec
• Advanced CMOS design for reliable operating characteristics
and low power.
• 50/60 Hz Line Frequency.
• 5V Operation (V
DD
- V
SS
).
• LS7540 (DIP); LS7540-S (SOIC) -
See Figure 1
-
APPLICATIONS:
• Screw-in and built-in adapter modules for converting table
and floor lamps to touch control for continuous dimming.
DESCRIPTION:
The LS7540 is a CMOS integrated circuit for controlling the
brightness of incandescent lamps with momentary touch. When
its TOUCH input is connected to a lamp body, the entire lamp
turns into a touch plate. A built-in AGC circuit allows for a wide
range of lamp sizes to be used, ranging from very small table
lamps to very large floor lamps. The brightness is controlled by
controlling the conduction angle of a triac in series with the lamp
and triggered by the TRIG/ output. Between off and maximum,
there are 124 steps of brightness levels, level zero being off and
level 124 being maximum. The phase reference of the Trig/ sig-
nal with respect to the AC line is maintained through the SYNC
input.
Touch Operation
The on/off and brightness control of the lamp is made with brief
touches of the lamp body as described below:
• In the off state a single touch will turn the lamp to full_on.
• At full-on a single touch will start a dim-cycle causing the
brightness to diminish gradually until the lamp turns off.
• During a dim-cycle a single touch will stop the dim-cycle and
lock in the brightness present at that time. Another touch will re-
start the dim-cycle from the present brightness causing the
brightness to ramp down towards off again. The start and stop of
dim-cycle can be repeated over and over again until the lamp
turns off.
PIN ASSIGNMENT
TOP VIEW
CLOCK
TRIG/
LSI
1
8
SYNC
2
7
V
SS
(-V )
LS7540
V
DD
(+V )
3
6
RAMP
TOUCH
4
5
CONTROL
FIGURE 1
SYNC Input
(Pin 2)
50Hz or 60Hz AC input for zero crossing detection.
V
DD
(Pin 3) Supply voltage positive terminal.
TOUCH Input
(Pin 4)
Input for sensing that a touch has been made on a lamp surface or
other touch plate. This action alters the state of the TRIG output as
described in the Touch Operation section of the General De-
scription.
CONTROL I/O
(Pin 5)
An external R-C network connected between this pin and V
DD
es-
tablishes the controlling feedback for the AGC Loop.
RAMP Input/Output
(Pin 6)
The ramp down rate of the brightness in the dimming cycle is regu-
lated by a resistor-capacitor (RC) pair connected to the RAMP in-
put. The ramp rate is equal to 4T
RC
per step, where T
RC
= 0.48RC.
Total ramp down time (T
T
) from maximum brightness to off is
equal to 496T
RC
.
Example:
R = 200kΩ, C = 0.22uF;
T
RC
= 0.48
x
(200
x
10
3
)
x
(0.22
x
10
-6
) = 0.02 sec.
Ramp rate = 4
x
T
RC
= 0.08 sec/step;
Total ramp time, T
T
= 496
x
T
RC
= 9.92 sec.
V
SS
(Pin 7) Supply voltage negative terminal.
TRIG/ output
(Pin 8)
The TRIG/ output produces a negative pulse every half cycle of
the AC line period to turn on a triac in series with the lamp or any
other load device. The brightness of the lamp is regulated by regu-
lating the conduction angle, Ø (See Fig. 2) of the TRIG/ signal.
The conduction angles at maximum brightness (level 124) and
mimimum brightness (level 1) are 162° and 50° with 0.91° in-
cremental steps.
I
NPUT/OUTPUT DESCRIPTION:
CLOCK Input
(Pin 1)
An external resistor connected between this input and V
DD
, along
with an internal capacitor and oscillator stage, generates a clock
which is used for all timing functions. The recommended value of
this resistor for 50Hz and 60Hz operation is specified in the
ELECTRICAL CHARACTERISTICS.
7540-060906-1