Allegro MicroSystems A5358CA-T

Overview

A5358CA-T from Allegro MicroSystems is a BiCMOS photoelectric smoke detector IC with integrated interconnect, timer, piezoelectric horn driver, low-battery detection, and chamber sensitivity monitoring. It operates from 6–12 V, draws only 12 µA average standby current, supports up to 50-unit daisy-chained networks, and complies with EN 14604 and BS 5446-1 for residential fire safety systems.

For engineers reviewing the A5358CA-T datasheet, A5358CA-T pinout, A5358CA-T application, or A5358CA-T equivalent, key selection criteria include its 16-pin DIP (Package A) footprint, dual-gain photoamplifier architecture, strobed VDD–5 V reference (STROBE), I/O interconnect logic with noise-immune sampling, and built-in hush/timer mode for nuisance-alarm suppression.

Technical Context

The A5358CA-T integrates a variable-gain photoamplifier whose gain is set by external capacitors C1 (supervisory/high-gain mode) and C2 (standby/low-gain mode), with internal 10% gain boost during local alarm to reduce false triggers. Its internal oscillator drives periodic 100 µs smoke-sensing windows every 10 s, minimizing power consumption while maintaining responsiveness.

It implements a three-stage speedup sensing scheme requiring two consecutive degraded-sensitivity cycles before issuing a chirp warning, and uses a dedicated STROBE output (VDD–5 V) as low-side reference for photoamplifier circuitry. Interconnect functionality relies on sampled I/O input with 95–137 ms high-level persistence requirement to reject noise, and active I/O output assertion during local alarm to trigger all networked units.

Key Specifications

Pinout & Package

Package: 16-pin plastic dual in-line package (DIP), through-hole mount, Pb-free matte-tin leadframe plating (suffix –T). Dimensions per JEDEC MS-001BB; 19.05 mm × 6.35 mm body, 2.54 mm pitch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar photoelectric smoke detector IC applications.

Compared with SM5201P and ISL28022IRZ, the A5358CA-T delivers fully integrated smoke detection logic, certified interconnect, and piezo drive in a single 16-pin DIP-reducing BOM count, layout complexity, and certification effort for EN 14604-compliant products.

Availability

A5358CA-T is available at Aetrix Electronics and suitable for residential fire alarm systems, interconnected smoke detector modules, and battery-powered safety devices requiring stable component supply, long-term lifecycle support, and regulatory compliance documentation.

Supply support for A5358CA-T includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Allegro MicroSystems is a U.S.-based designer and manufacturer of high-performance magnetic sensors, motor drivers, and precision analog ICs, headquartered in Manchester, NH.

The A5358CA-T belongs to Allegro's dedicated smoke detector IC product line, engineered specifically for EN 14604/BS 5446-1 compliance, ultra-low-power battery operation, and robust interconnect functionality in residential life-safety applications.

FAQ

What is the operating voltage range of the A5358CA-T?

The A5358CA-T operates from 6 V to 12 V DC, making it compatible with standard 9 V alkaline batteries without external regulation. Its internal band-gap reference and low-battery detection circuitry function reliably across this full range, with a defined threshold of 6.9–7.5 V for low-battery chirp activation. This ensures consistent performance throughout battery discharge.

How does the A5358CA-T implement interconnect functionality for multi-unit alarm systems?

The A5358CA-T uses its I/O pin for daisy-chained interconnect: during local alarm, it actively drives the pin high; as an input, it samples the line every ~42 ms and requires three consecutive high samples plus one additional cycle (~95–137 ms total high time) to trigger a remote alarm. This design provides strong noise immunity while supporting up to 50 interconnected units without external logic.

What is the purpose of the STROBE pin on the A5358CA-T?

The STROBE pin on the A5358CA-T outputs a regulated VDD–5 V reference used as the low-side bias for the internal photoamplifier. This isolated, strobed supply minimizes power consumption and improves noise rejection in the sensitive optical detection path. Its voltage remains stable across supply variations, with line regulation of –60 dB and temperature coefficient of 0.01 %/°C.

Can the A5358CA-T be used with surface-mount smoke chambers?

Yes, the A5358CA-T supports surface-mount integration via its companion part A5358CLWTR-T (16-pin SOICW), but the A5358CA-T itself is packaged in a 16-pin through-hole DIP (Package A). Both variants share identical electrical functionality, pinout, and application circuitry-only the package differs. Layout adaptation is required, but schematic design and component selection remain unchanged.

Does the A5358CA-T support hush or temporary alarm silencing?

Yes, the A5358CA-T implements a certified hush/timer mode: applying a high-to-low transition on the TEST pin while HUSH >1.5 V initiates a 10-minute (nominal) period of reduced sensitivity. During this mode, the smoke comparator reference shifts to a lower level set by an external Rx1/Rx2 divider between VDD and STROBE, suppressing alarms from nuisance sources like cooking steam while retaining full detection capability for real threats.