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PDF LS7217 Data sheet ( Hoja de datos )
| Número de pieza | LS7217 | |
| Descripción | PHOTO CONTROLLED OUTDOOR LIGHTING | |
| Fabricantes | LSI | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LS7217 (archivo pdf) en la parte inferior de esta página. Total 6 Páginas | ||
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LSI/CSI
LS7217
LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747 (631)271-0400 FAX (631) 271-0405
PHOTO CONTROLLED OUTDOOR LIGHTING WITH PROGRAMMABLE TIMER Sep 2014
FEATURES:
• Input interface to a LDR or a photo transistor
• Programmable Duration Selection
• Shunt regulator
• 50Hz / 60Hz time base selection
• Relay Driver output
• 6.0V ± 0.75V operating voltage range (VDD – VSS)
• LS7217 (DIP), LS7217-S (SOIC) – See Figure 1
PIN ASSIGNMENT
APPLICATIONS
Lighting control for outdoor area lighting, street lighting, parking lot
lighting, billboards lighting
DESCRIPTION
The 7217 is a programmable Timer IC designed to turn on a relay at
night and turn off the relay at dawn or after a selectable number of
hours. Figure 2 shows a typical application schematic.
PIN DESCRIPTION:
The following describes the operation of the inputs and outputs of the
IC.
FIGURE 1
The Time Select Table is as follows:
TS1 TS2
00
01
10
11
Time Duration
4 Hours
6 Hours
8 Hours
Dusk-to-Dawn
VDD (Pin 2)
VDD is the supply voltage positive terminal. It is regulated internally in
the IC. The internal voltage regulator produces 6.0V ± 0.75V.
Dusk-to-Dawn duration is determined solely by the photo-cell; i.e.,
the Relay output is on whenever the photocell recognizes an ambient
dark condition.
VSS (Pin 6)
VSS is the supply voltage negative terminal.
50Hz / 60Hz SELECT Input (Pin 8)
A high at this input selects the correct timing for 50Hz operation.
Floating this input selects the correct timing for 60Hz operation. A
low at this input places the LS7217 into Test Mode where the
timeouts are accelerated by a factor of 60.
50Hz / 60Hz Input (Pin 7)
This input is the clock source for all timing functions. This input has a
Schmitt trigger to ensure a clean internal clock waveform.
TIME SELECT Inputs TS1, TS2 (Pins 4, 5)
The two Select inputs determine the time duration that the Relay
output stays on after the photo input goes low. Both inputs have
internal pull-down transistors so that float is logic zero and
connection to VDD is logic 1.
PHOTO Input (Pin 3)
The photo input has hysteresis for a positive trip point. The input will
work with a Light Dependent Resistor (LDR) or a photo-transistor
connected between the input and VDD. The photo device has low
impedance in the presence of ambient light and high impedance in
the presence of ambient darkness.
The IC is configured so that the detection of a light condition must
remain for 6.0 seconds (± 0.5 seconds) continuously in order to be
recognized as a valid light condition. A dark condition must
remain for 1.0 second (± 0.25 seconds) continuously in order to be
recognized as a valid dark condition.
RELAY Output (Pin 1)
This output is configured to drive the base of an external NPN
transistor (see Figure 2). A valid dark condition at the PHOTO input
causes the RELAY output to switch high and a valid light condition at
the PHOTO input causes the output to switch low.
7217-091814-1
1 page  
FIGURE 4. BATTERY BACK-UP FOR AC POWER FAILURE
R1=1kΩ
R2=270kΩ
R3=100kΩ
R4=100kΩ
R5=1MΩ
R6=10kΩ
R7=10kΩ
R8=50kΩ
R9=1MΩ
C1=220uF
C2=470uF
C3=0.1uF
C4=0.1uF
C5=0.1uF
C6=470pF
D1=1N4004
D2=1N4004
D3=1N4004
D4=1N4004
D5=1N4004
Q1=2N2222
U1=ICM7555
Figure 4 shows how to connect a back-up battery circuit to the LS7217 timer in case of power failure.
Upon ac power failure, U1 generates either a 50Hz or 60Hz clock (set by R8) so that the LS7217 timeout
remains uninterrupted. When power returns timeout continues as if no ac interruption occurred.
7217-091814-5
5 Page | ||
| Páginas | Total 6 Páginas | |
| PDF Descargar | [ Datasheet LS7217.PDF ] | |
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