A5350CA

Overview

The A5350CA is a low-current BiCMOS integrated circuit designed for ionization-type smoke detectors. It operates on a single 6.0 V to 12.0 V supply and features an internal oscillator with a standby period of 1.67 seconds, during which the device powers down for 1.66 seconds and samples for smoke for only 10 ms. The IC supports interconnecting up to 125 units via its I/O pin. Electrical characteristics include a typical supply current of 5.0 µA at 9.0 V, a low-battery threshold of 7.5 V (adjustable), and horn output voltages ranging from 6.3 V to 8.8 V depending on load and supply. It is housed in a 16-pin DIP package.

Feature Summary

• Integrated ionization smoke detection with active guard amplifiers to minimize surface leakage currents
• Network capability allowing interconnection of up to 125 detector units for synchronized alarms
• Built-in piezoelectric horn driver and visible LED output for alarm indication
• Internal reverse battery protection and power-on reset functionality

Applications

• Battery-operated ionization smoke detectors
• Interconnected fire alarm systems requiring synchronized unit response
• Low-power safety and security applications using alternative sensors or switches

Procurement Notes

Verify component status carefully as this part is discontinued and not recommended for new designs. Confirm availability through authorized distributors or secondary markets if sourcing for replacement purposes. Ensure compliance with RoHS requirements by selecting the appropriate suffix if lead-free versions are required for specific regulatory environments.

Selection Notes

Select the A5350CA when designing legacy ionization smoke detectors requiring networked alarm capabilities. Consider external resistor values for sensitivity adjustment and low-battery threshold setting based on specific chamber characteristics. Ensure the use of low-leakage capacitors for the oscillator timing circuit to maintain accurate sampling intervals and low standby current consumption.

Part Context

The A5350CA belongs to Allegro MicroSystems' line of specialized interface ICs for sensor applications. It is part of the A5350 family, specifically tailored for ionization smoke detection. This component represents a dedicated solution for integrating sensing, processing, and alarm driving functions into a single low-power package suitable for battery-powered safety devices.

Replacement Considerations

No direct public substitute part numbers are documented for the A5350CA. As a discontinued product, redesigning the application with a modern smoke detector IC is recommended. If a physical drop-in replacement is strictly necessary, consult Allegro MicroSystems for potential obsolescence management options or equivalent functional alternatives.

FAQ

How does the A5350CA handle interconnect noise?

The I/O pin includes filtering that requires the input signal to remain high for approximately 93.9 ms to trigger an alarm, providing significant immunity to noise.

Can the low-battery threshold be adjusted?

Yes, the threshold can be externally adjusted by connecting a resistor between the LOW-V SET pin and either VDD or VSS to increase or decrease the voltage level.

What is the purpose of the GUARD1 and GUARD2 pins?

These pins provide active guard amplifiers adjacent to the detector input to keep surface leakage currents to a minimum and allow measurement of the input voltage without loading the ionization chamber.