描述 Description

The A5358 is a low-current BiCMOS circuit providing all of the required features for a photoelectric type smoke detector. This device can be used with an infrared photoelectric chamber to sense scattered light from smoke particles. A networking capability allows as many as 50 units to be interconnected so that if any unit senses smoke all units will sound an alarm. Special features are incorporated in the design to facilitate calibration and testing of the finished detector. The device is designed for applications that comply with European Standard EN 14604 and British Standard BS 5446, Part 1.
A variable-gain photoamplifier can be directly interfaced to an infrared emitter-detector pair. The amplifier gain levels are determined by two external capacitors and are internally selected depending on the operating mode. Low gain is selected during standby and timer modes. During a local alarm, this low gain is increased (internally) by approximately 10% to reduce false triggering. High gain is used during pushbutton test and to periodically monitor the chamber sensitivity during standby.
The internal oscillator and timing circuitry keep standby power to a minimum by sensing for smoke for only 100?μs every 10?s. A special three-stage–speedup sensing scheme is incorporated to minimize the time to an audible alarm and also to reduce false triggering. Chamber sensitivity is periodically monitored and two consecutive cycles of degraded sensitivity are required for a warning signal (chirp) to occur.

特性 Features

?Low average standby current for long battery life
?Interconnect up to 50 detectors
?Piezoelectric horn driver
?Low battery detection (all internal)
?Chamber sensitivity test and alarm
?Power-on reset (POR)
?Internal timer and control for reduced sensitivity mode
?Built-in circuits to reduce false triggering
?6 to 12 V operating range
?ESD protection circuitry on all pins

簡介

A5358屬于集成電路（IC）的傳感器檢測器接口。由制造生產(chǎn)的A5358傳感器和檢測器接口該系列產(chǎn)品可執(zhí)行信號調(diào)節(jié)、數(shù)據(jù)轉(zhuǎn)換、激勵生成和/或各種將傳感器或變送器機構(gòu)連接到主機設(shè)備所需的其他功能。示例包括用于 CCD 圖像傳感器的控制器、用于 4-20 mA 接口和類似應(yīng)用的電流變送器、超聲變送器前端、惠斯通電橋接口等。