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| UL (R) LSI/CSI LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747 Relay OUT V DD (+V ) Photo Resistor Time Select1 1 LS7217 (631) 271-0400 FAX (631) 271-0405 January 2008 A3800 PROGRAMMABLE LIGHT-ACTIVATED TIMER FEATURES: * Input interface to Photo Resistor * 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 APPLICATIONS Lighting control for low voltage landscape lighting, etc. PIN ASSIGNMENT TOP VIEW 8 7 6 5 50Hz / 60Hz Select 50Hz / 60Hz VSS (-V ) Time Select2 LSI LS7217 2 3 4 DESCRIPTION FIGURE 1 The LS7217 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 circuit is powered from a step-down trans- TIME SELECT Inputs TS1, TS2 (Pins 4, 5) former and the output drives low-voltage AC loads such as in- The two Select inputs determine the time duration that the Relay output stays on after the photocell goes low. Both incandescent light bulbs. puts have internal pulldown transistors so that float is logic zero and connection to VDD is logic 1. The Time Select TaPIN DESCRIPTION: ble is as follows: The following describes the operation of the inputs and outputs of the IC. Time Select1 Time Select2 Time Duration 0 0 4 Hours VDD (Pin 2) 0 1 6 Hours VDD is the supply voltage positive terminal. It is regulated in1 0 8 Hours ternally in the IC. The internal voltage regulator produces 1 1 Dusk -to-Dawn 6.0V 0.75V. A series resistor is required to limit current into the regulator from 5mA to 10mA over the full transformer opDusk to Dawn duration is determined solely by the photoerating voltage range. 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 / 60 Hz SELECT Input (Pin 8) A high at this 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. PHOTO RESISTOR Input (Pin 3) The photo resistor input has hysteresis for a postiive trip point. The input will work with a photo resistor connected between the input and VDD. The photo resistor provides a low impedance in the presence of ambient light and a high impedance in the presence of ambient darkness. The IC is configured so that detection of a light condition must remain for 6.0 seconds ( 0.5 seconds) continuously 50Hz / 60 Hz Input (Pin 7) This input is the clock source for all timing functions. This in- in order to be recognized as a valid light condition. A put accepts a 9VAC to 16VAC input voltage. An external dark condition must remain for 1.0 seconds ( 0.25 secdropping resistor of 220k Ohms is needed to limit current. onds) continuously in order to be recognized as a valid This input has a Schmitt trigger to ensure a clean internal dark condition. clock waveform. RELAY Output (Pin 1) This output is configured to drive the base of an external NPN transistor (see Figure 2). 7217-012608-1 D1 10VAC - 15VAC From Transformer R1 Time Select 50/60Hz Select MOV D2 R2 K1 LDR R4 4 3 6 R3 5 8 27 LS7217 1 + C1 - C2 Q1 10VAC -15VAC to Light Bulbs FIGURE 2. TYPICAL LANDSCAPE LIGHTING APPLICATION SCHEMATIC D1 = 1N4004 D2 = 1N4004 C1 = 220uF, 25V C2 = 470pF, 10V Q1 = 2N3904 (Typical) Note: All resistors, 1/4W R1 = 1k R2 = 220k R3 = 25k R4 = Silonex NSL-19M51 (Typical) 7217-012608-2 ABSOLUTE MAXIMUM RATINGS: (All voltages referenced to VSS) DC Supply Voltage Voltage (Any Pin) Operating Temperature Storage Temperature SYMBOL VDD VIN TA TSTG VALUE +8 VSS -0.3 to VDD + 0.3 - 20 to +85 -40 to +150 UNIT V V C C DC ELECTRICAL CHARACERISTICS: (TA = 25C, VDD = 6.0V unless otherwise specified. PARAMETER TS1, TS2 Low TS1, TS2 High 50/60 Hz Low 50/60 Hz High Photo Resistor Inhibit Threshold Enable Threshold Input Current (All inputs high) 50Hz/60Hz Select ] TS1, TS2 ] Output Current Sourcing, VO = 0.7V Sinking, VO = 0.4V SYMBOL TLO THI VHZL VHZH VIT VET MIN 3.0 4.4 3.5 - TYP - MAX 1.4 2.9 2.9 UNIT V V V V V V IIH - 24 - mA IOH IOL 4.0 -50 - - mA mA The information included herein is believed to be accurate and reliable. However, LSI Computer Systems, Inc. assumes no responsibilities for inaccuracies, nor for any infringements of patent rights of others which may result from its use. 7217-081307-3 |
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