Brief description:
The A5303 is a low-power BiCMOS photoelectric smoke detection circuit with ultra-low standby current, a working life of up to 10 years, and a low-cost battery. The device can be used together with an infrared light cavity to detect light scattered by smoke particles. Because of the networking function, the components are connected to each other, and when one component detects smoke, all components will issue an alarm. Many special functions are integrated in the device, which can simplify the calibration and testing of the detector.
The variable gain optical amplifier can be directly connected to the same infrared emitter-detector pair. The gain level of the amplifier is determined by two external capacitors, while the internal is determined by the operating mode. In standby and timing modes, low gain is used. During local alarms, this low gain is increased by approximately 45%, thereby providing hysteresis. The high gain is used in the button test, and the cavity sensitivity can be monitored periodically during standby.
The internal oscillator and timing circuit only have a time of 100μs every 10 seconds for smoke detection, thereby minimizing standby power consumption. The device integrates a special third-order acceleration sensing architecture to alert in the shortest time while reducing false triggers. The cavity sensitivity is monitored periodically, and if the sensitivity decreases for two consecutive cycles, an alarm signal will be triggered.
The A5303 is available in a thin 20-lead TSSOP lead-free package (0.65mm lead pitch).
A5303 main features and advantages
· Low average standby current ensures 10 years of battery life
· 2.3V to 5.5V operating voltage
· Interconnection options
· Logic output for controlling external sound IC
· Low battery detection and alarm
· Triple horn chirp is used to distinguish cavity alarm
· Power-on reset (POR)
· I / O digital filter has anti-noise
· Timer (quiet) mode is used to shorten the sensing period
· Built-in circuit reduces false trigger
· ESD protection at all pins
· Temporal angle mode, in line with UL217, NFPA72, ISO8201 standards
· Blocking alarm indicator light indicates the device that issued the alarm
typical application:
Figure 1 A5303 typical application circuit
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