OUTDOOR LIGHTING. LS7217 Datasheet
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
• 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
Lighting control for outdoor area lighting, street lighting, parking lot
lighting, billboards lighting
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.
The following describes the operation of the inputs and outputs of the
The Time Select Table is as follows:
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
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.
FIGURE 2. DUSK TO DAWN AUTO ON/OFF OUTDOOR LIGHTING APPLICATION
R1=68kΩ, 1/2W, @120VAC
R1=240kΩ, 1/2W, @240VAC
R2=6.8kΩ, 2W, @120VAC
R2=27kΩ, 2W, @240VAC
R3=4.7kΩ, 2W, @120VAC
R4=680kΩ, 2W, @240VAC
R4=1MΩ, 2W, @120VAC
R5, R6=As needed for driving relay
R7=100kΩ, 1/4W Potentiometer
C1=0.33uF, 200VAC, @120VAC
C1=0.2uF, 400VAC, @240VAC
Z=15V Zener, 1W
LOAD=Incandescent, LED, fluorescent or HID
**For the photo-sensitive device use either LDR, R10=Silonex NSL-19M51 or use
Photo-transistor, Q2=Vishay TEPT 4400.
NOTE1: This application circuit can be used for lighting control of public spaces such as
Parking Lots, Billboards, street lamps etc.
NOTE2: Indicated connections of pins 4 and 5 keep the lamp on from dusk to dawn. See page 1
for configuring pins 4 and 5 connections to select 4, 6 or 8 hours on-time.
ABSOLUTE MAXIMUM RATINGS: (All voltages referenced to VSS)
DC Supply Voltage
Voltage (Any Pin)
VSS - 0.3 to VDD + 0.3
-20 to +85
-40 to +150
DC ELECTRICAL CHARACERISTICS:
(TA = 25°C, VDD = 6.0V unless otherwise specified.
TYP MAX UNIT
TS1, TS2 Low
TS1, TS2 High
50/60 Hz Low
50/60 Hz High
(All inputs high)
50Hz/60Hz Select ]
RELAY Output Current
Sourcing, VO = 0.7V IOH
Sinking, VO = 0.4V IOL
4.0 - - mA
The information included herein is believed to be
accurate and reliable. However, LSI Computer Systems,
Inc. assumes no responsibilities for inaccuracies, or for
any infringements of patent rights of others which may
result from its use.