Welcome to the training module on Microchip’s Photoelectric Smoke Detectors.
Sensors are appearing in more and more general consumer products. Many other industries also widely use sensors within applications, some of which require high accuracy and reliability. A few examples are within chemical processing, high-tech material production, pharmaceuticals, just to name a few. Accuracy is critical within these applications to ensure high yields and an overall quality production process
As just stated, industrial applications such as chemical processing, pharmaceuticals, and industrial production require tight temperature control and highly accurate ingredient mixing. Consumer products and more portable type products such as hand held products, gaming controls (Nintendo Wii™) and wireless systems are driving the need for low power and smaller sized solutions. These requirements relate to the cost, reliability and performance of sensing solutions within their end product. All of which are critical considerations during a design and new product development cycle. In most situations designers and new product teams deal with tradeoffs between typical application requirements. Microchip offers many different alternatives within the signal chain which gives designers the flexibility to make the right tradeoff decision.
This page shows Horn Driver Road MAP which are Piezoelectric based on, baseline ASIC Products: it includes RE46C100 basic model, Vdd 6V - 16V, RE46C101 with LED Driver, Vdd 6V - 16V, RE46C104 with Voltage Converter, Vdd 4V-8V, RE46C117 with Charge Pump, Vdd 2V - 5V
This page gives information about smoke detector products it includes RE46C140, RE46C141, RE46C143, RE46C144, RE46C145.
Infrared LED is used as a light source and A light chamber is used to detect “reflected light” Light is scattered by smoke particles and the scattered light is detected using photo detector. High Gain Amplifier used to amplify low signal, High Current Drive for LED bias
This page gives smoke detector product portfolio which includes RE46140, 141, 145, 143, 144 products. Temporal horn pattern is in compliance with the National Fire Protection Association (NFPA) regulations.
The RE46C140 is low power CMOS photoelectric type smoke detector IC. With minimal external components this circuit will provide all the required features for a photoelectric type smoke detector.
This page shows functional block diagram of smoke sensor, it has gain selectable photo amplifier for use with an infrared emitter/detector pair. An internal oscillator strobes power to the smoke detection circuitry for 100us every 10 seconds to keep standby current to a minimum. If smoke is sensed the detection rate is increased to verify an alarm condition. A check for a low battery condition and chamber integrity is performed every 43 seconds when in standby. The temporal horn pattern supports the NFPA 72 emergency evacuation signal. An interconnect pin allows multiple detectors to be connected such that when one units alarms, all units will sound. An internal 10 minute timer can be used for a reduced sensitivity mode.
This page shows typical application circuit using smoke sensor device RE46C14X. The internal oscillator has a nominal period of 10mS. Normally the analog circuitry is powered down to minimize standby current (typically 4uA at 9V). Once every 10 seconds the detection circuitry (normal gain) is powered up for 10 ms. Prior to completion of the 10mS period the IRED pulse is active for 100 us. Three consecutive smoke detections will cause the device to go into alarm and the horn circuit and interconnect will be active. Once every 40 seconds, the status of the battery voltage is checked. This status is checked and latched at the conclusion of the LED pulse.
This page gives differences of Ionization Smoke Detectors vs. Photoelectric Smoke Detectors.
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