PIR-sensor-based Lighting Device with Ultra-low Standby Power Consumption Cheng-Hung Tsai 1 , Ying-Wen Bai 2 , Chun-An Chu 3 , Chih-Yu Chung 4 and Ming-Bo Lin 5 1 5 Department of Electronic Engineering, National Taiwan University of Science and Technology 2 3 4 Department of Electrical Engineering Fu Jen Catholic University 1 ee2016@mail.fju.edu.tw, 2 bai@ee.fju.edu.tw, 3 498506101@mail.fju.edu.tw, 4 499216234@mail.fju.edu tw, 5 mblin@mail.ntust.edu.tw Abstract –In this paper we present a way to reduce the standby power consumption of a PIR-sensor-based lighting device. Generally although a PIR-sensor-based lighting device will turn on when motion is detected, and will turn off when the motion disappears, the device still consumes 1-3 W power when the lamp is off. In our design the device consumes 0.007 W when the light is off, and is not only easy to set up but also inexpensive. Our circuit supplies the lamp with power when motion is detected; when the motion disappears it turns the lamp off, and the electric power is shut off in order to reduce the standby power. We use an MCU which receives signals from a PIR sensor which detects any individual approaching the device. The MCU controls the SSR On/Off when used as a lighting switch for shutting off the standby power. The MCU monitoring program provides automatic detection of any individual by means of the PIR sensor. The MCU has internal modules to simplify the hardware circuit design. The circuit component count, cost and power consumption are low. Keywords: PIR-sensor-based Lighting Device, Standby Power, PIR, Power Consumption I. INTRODUCTION The pyroelectric infrared (PIR) sensor-based lighting device is now in widespread use. This device with its built-in PIR sensor cuts the electricity when no user is near the PIR sensor. The PIR sensor turns the light on instantly when someone enters the room, and off after the individual exit. Thus a PIR-sensor-based lighting device saves one from fumbling for that light switch or leaving lights on for hours on end which is great for both energy saving, security and safety. And because the device only comes on when the PIR sensor is activated, no energy is wasted. The light is suitable for a number of locations, including the laundry room, attic, basement, pantry, closet, kitchen, path light, outdoor wall lantern, hallway, garage, bathroom and even children's rooms. But the device cannot be switched off completely without being unplugged. In this paper we define three states of the PIR-sensor-based lighting. In the standby state the lighting device is connected to a power source but does not produce light. In the active state the device’s light is on when the PIR sensor is activated. The cut-off state means that the device is unplugged from its power source and does not consume any electricity. The lighting device in standby state draws power 24 hours a day. We call the power consumption, used while there is no light and the device is plugged in the power socket “standby power”. This amount is typically small, but the sum of the standby power consumption of all PIR-sensor-based lighting devices within a household becomes significant [1]-[5]. Though the lighting device in standby state is not performing its main function of lighting it is often performing some secondary function like sensing IR and ambient light that cannot be switched off unless the unit is unplugged. This secondary function requires not only a specific low DC voltage to operate but also a continuous power supplied by an AC/DC converter which has no power-off switch. The AC/DC converter as a power supply in the lighting device converts AC 120 V into low voltage DC for the secondary function operation [6]. The AC/DC converter, which is very inefficient at low DC voltage, has a power consumption between 1 and 4 W, which is many times more than the power actually used for the secondary function. Therefore, in the long run, the PIR-sensor-based lighting device consumes much power while in the standby state. In 2000 the International Energy Agency (IEA) adopted a proposal to reduce the standby power of all electrical apparatus to less than 1 Watt within ten years [7]-[9]. Thus it is imperative to develop new techniques to reduce the power consumption in electronic circuits. A recently published survey shows that various attempts have been made to reduce such power leakage to make the adapter more efficient [10]-[13]. Another way to improve efficiency is accurate control of the apparatus by both software and microcontroller [14]-[16]. In this paper we present a design to reduce the standby power consumption of the PIR-sensor-based lighting device. The standby power consumption of our design is reduced to 7 mW [1]. We call our design “ultra-low standby power PIR-sensor-based lighting”. It is also easy to set up, inexpensive, and saves power more efficiently. Consequently it is suitable for use in most locations. In the long run the lighting saves much more power. The organization of this paper is as follows. In Section II we present the circuit designs and a flowchart of our design. In Section III we present the measurement of the power consumption of our design to verify the total power saved. In Section IV we draw the conclusions. II. CIRCUIT DESIGN OF ULTRA-LOW STANDBY POWER PIR LIGHTING The PIR-sensor-based lighting device is turned on only when motion is detected. When motion disappears, the time when the light is switched off, and the duration of the lighting can be adjustable. The lighting device has an ambient light sensor to detect ambient light. If the ambient light suffices, the lighting is not turned on even if any motion is detected. On the contrary, the lighting device will immediately turn on when motion is detected. Both the threshold of the ambient light and its duration time are adjustable. The adjustable duration of lighting, the sensing of ambient light and its threshold are all internal functions of the PIR lighting device. In general, the PIR-sensor-based lighting device is plugged into AC 120 V as its power source. The internal modules in the lighting require low DC voltage to operate,