Microchip Technology overview of the RE46C180 Programmable Ionization Smoke Detector IC. 1
This programmable smoke detector IC allows battery operation using a 9V battery. The low quiescent current extends the battery life of the system. A 500 mah battery can have a battery life of 10 years when using the RE46C180. Programmable calibration provides adjustment of the overall system performance. Programmable system features such as horn pattern select, low battery hush, hush options, smart IO options, alarm memory, horn synchronization, auto alarm locate, and end of life allow the smoke detector system design to meet different regulatory requirements and to provide a range of model features with a single IC. The interconnect of up to 40 devices with local alarm memory, auto alarm locate and horn synchronization allows the source of nuisance alarms to be easily identified in larger smoke detector configurations. System self checks such as low battery and chamber test insure proper operation of the smoke detector over its operating life. 2
The RE46C180 is provided in a 16 pin PDIP and SOIC packages. 3
The IC provides programmable calibration. The standby sensitivity has 32 possible settings. The hysteresis setting has 9 possible settings. The hush sensitivity has 16 possible settings. The chamber test has 32 possible settings. The low battery threshold has 4 possible settings Manual calibration in manufacturing is eliminated. The smoke detector manufacturer has unprecedented control over how the smoke detector will respond to smoke conditions along with the ease and speed of electronic calibration. 4
One part can meet multiple model and regional regulatory requirements. Programmable features include tone select, low battery hush enable, smart hush enable and configuration, smart IO enable and configuration, alarm memory enable and configuration, auto alarm locate, horn synchronization and end of life (EOL) enable. 5
When a smoke detector experiences a false alarm for a known reason such as cooking an easy way to silence the alarm is useful. Electronic programming controls how hush is invoked, how long hush runs, and how hush is exited. This allows the manufacturer to easily produce smoke alarms with different capabilities using a single IC and PCB. 6
An interconnected system of smoke alarms allows all the connected smoke detectors to sound a smoke alarm when only one smoke detector has detected smoke. If smoke is detected in the basement of a home the smoke alarm will sound in the upstairs sleeping quarters of a home. The interconnect function has a digital filter which will identify pulses greater than or less than 290 ms long. Pulses less than 290 ms are identified as a remote CO alarm signal. If the CO alarm is enabled the RE46C180 will issue a CO temporal horn pattern. Pulses greater than 290 ms are identified as a remote smoke alarm signal and a remote smoke alarm will sound with the selected horn pattern. 7
Interconnect allows up to 40 smoke detectors to be connected together. When Smoke Detectors are interconnected they all sound together if one triggers an event. As wonderful as it is to be warned in your bedroom about a fire in the basement, it is not so pleasant if the event was a false trip. Unfortunately, with previous generation detectors so looped one cannot tell which detector committed the offense and should be replaced if defective or moved if in a bad location, as in too close to the kitchen or bathroom. Alarm Memory removes the guess work. The detector that triggered the alarm will remember and give a different signal so that it can be identified. With a detector easily identified installation time and cost is quickly reduced. 8
When multiple interconnected smoke detectors receive a remote alarm signal, the horn pattern timing is set by the smoke detector the horn is connected to. The meaning or effectiveness of the temporal horn can be lost as different timing for each smoke detector causes the on / off state of each smoke detector to overlap the other temporal horn patterns differently. Horn synchronization causes the on / off state of all interconnected smoke detectors to occur at the same time. Horn synchronization effectively increases the volume of the temporal pattern since all horns are on or off at the same time. Horn synchronization produces a effect similar to panel based systems where strobes and horns are synchronized. 9
When interconnected smoke detectors are all sounding the temporal horn pattern, the location of the local alarm can only be determined by finding smoke detectors with the red LED flashing. With auto alarm locate the smoke detectors in local alarm can be found by listening to the alarms. Smoke detectors in local alarm will sound the temporal horn pattern continuously. Smoke detectors in remote alarm are turned off during every fourth temporal horn pattern. By moving to the sound when remote alarm detectors are not sounding the temporal horn pattern, the smoke detectors in local alarm can be easily found and the fire threat validated. Auto Alarm Locate will only work if horn synchronization is enabled. 10
The End of Life feature addresses concerns that after 10 years of powered operation, the smoke detector may not be as effective as needed and should be replaced. This feature is considered especially necessary when the smoke detector is powered by a 500mAH battery which will allow a RE46C180 smoke detector to operate for 10 years without battery replacement. Even in the case of replaceable batteries, it may be prudent to replace a smoke detector after 10 years. 11
4 to 6 passive components are eliminated. No manual calibration requirement simplifies the system design as well as reducing manufacturing costs. 12
Low quiescent current extends battery life. 10 year smoke detector operation is possible with a 500mAH battery. Programmable Calibration along with test modes simplifies smoke detector design and manufacturing. All smoke alarm thresholds are programmable as compared to previous generation of smoke detector ASIC s. This gives the manufacturer unprecedented control over the smoke detector design and operation. Manual calibration is also eliminated. Programmable features allow different model and regulatory requirements to be met with a single IC and PCB. This reduces parts inventory and manufacturing requirements. When hush is enabled, how hush is invoked, how long hush runs, and how hush is exited is all configurable by the manufacturer using the RE446C180 programmability. 13
Interconnect with Alarm Memory allows the IC to remember if it was in local alarm making it easy to determine which device set off the group of smoke detectors. This allows a defective unit or bad location (for example, by or in a Kitchen or bathroom) to be found easily. The Interconnect digital filter can distinguish between a remote smoke and a carbon monoxide signal on the interconnect line. When enabled the CO temporal horn pattern will sound. The Interconnect charge dump allows the interconnect line to be quickly cleared when coming out of alarm state. The Low Battery Test with Hush allows the battery to be tested for proper operating voltage and allows the low battery alarm to be silenced when necessary. This feature warns the user that the smoke detector is not properly powered. The Chamber Test warns that the smoke detector is not operating properly and allows the end user to replace a defective unit. 14
Horn Synchronization synchronizes the temporal horn pattern of multiple interconnected piezo horns. This makes the temporal horn pattern more recognizable and increases the effective volume of the horns. Auto Alarm Locate allows smoke detectors in local alarm to be easily by listening to the temporal horn pattern. Smoke detectors in local alarm will sound the alarm continuously while smoke detectors in remote alarm will be silenced on every fourth temporal horn pattern. This means that the location of the local alarm can be found by listening and the threat validated. The End of Life Alarm warns that the smoke detector is 10 years old and that the smoke detector should be replaced. 15
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The RE46C180 is a standard product provided in a lead free 16 pin PDIP or SOIC package which can be taped and reeled. 17
Please visit www.microchip.com for data sheet and additional details. Samples are available at sample.microchip.com and the product can be purchase online at www.microchipdirect.com. Microchip has made a concerted effort to support the needs of the Smoke Detector industry. From low power operational amplifiers and power management products to the PICmicro and dedicated Smoke Detector I.C.s like the ones we are introducing here look to Microchip for Smoke Detector support. 18
Thank you for your time. 19