Allegro MicroSystems A5358CLWTR-T

Overview

A5358CLWTR-T from Allegro MicroSystems is a BiCMOS photoelectric smoke detector IC with integrated interconnect, timer, piezoelectric horn driver, and low-battery detection. It delivers 12 μA standby current, supports up to 50-unit daisy-chained networks, operates from 6–12 V, and complies with EN 14604 and BS 5446-1 for residential and commercial fire safety systems.

For engineers reviewing the A5358CLWTR-T datasheet, A5358CLWTR-T pinout, A5358CLWTR-T application, or A5358CLWTR-T equivalent, key selection criteria include its 16-pin SOICW package, 100 µs/10 s smoke-sensing duty cycle, three-stage speedup sensing architecture, internal oscillator (10.5 ms typical period), and dual-gain photoamplifier controlled by external C1/C2 capacitors.

Technical Context

The A5358CLWTR-T integrates a variable-gain photoamplifier with gain selection determined by external C1 (supervisory mode) and C2 (standby mode) capacitors, where Ae = 1 + (C/10) with C in pF. Its internal oscillator sets both STROBE and IRED timing via OSC CAP and TIMING RES pins, generating a 10.5 ms nominal clock period and 105 µs IRED pulse width.

It implements a noise-immune interconnect protocol requiring three consecutive high samples on the I/O pin (≈95–137 ms minimum high time) to trigger remote alarms, while suppressing LED output during remote events and prioritizing local smoke detection. The HUSH pin enables a 10-minute reduced-sensitivity "hush" mode via external resistive divider referencing STROBE.

Key Specifications

Pinout & Package

The A5358CLWTR-T is supplied in a 16-pin SOICW (Small Outline Integrated Circuit Wide) surface-mount package, Pb-free with 100% matte-tin leadframe plating, rated for –25°C to +75°C operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SM9100A and IS31FL3728-QFLS2-TR, the A5358CLWTR-T uniquely integrates complete photoelectric detection, interconnect arbitration, hush functionality, and chamber diagnostics in a single BiCMOS IC-eliminating external logic, reducing certification effort, and enabling certified standalone or networked designs without firmware development.

Availability

A5358CLWTR-T is available at Aetrix Electronics and suitable for residential fire alarm systems, commercial interconnected detector deployments, and manufactured housing safety solutions requiring stable component supply and long-lifecycle support.

Supply support for A5358CLWTR-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 driver ICs, and precision analog power ICs for automotive, industrial, and consumer applications.

The A5358 product line was developed specifically for photoelectric smoke detection systems requiring EN 14604 and BS 5446-1 compliance, integrating sensing, timing, interconnect, and audio alert functions into a single BiCMOS die to simplify certification and reduce system cost.

FAQ

What is the operating voltage range for the A5358CLWTR-T?

The A5358CLWTR-T operates from 6 V to 12 V DC referenced to VSS. This range accommodates standard 9 V alkaline batteries and regulated 6–12 V DC supplies used in certified smoke detectors. Operation below 6 V disables functional blocks including the oscillator and horn drivers, while absolute maximum rating is 15 V.

How does the A5358CLWTR-T implement interconnect functionality across multiple units?

The A5358CLWTR-T uses its bidirectional I/O pin to form daisy-chained networks of up to 50 units. When any unit detects smoke locally, it drives I/O high; connected units sample this signal every ~42 ms and require three consecutive high readings (≥95 ms minimum) to trigger their own alarms-providing robust noise immunity without external protocol controllers.

What is the purpose of the C1 and C2 pins on the A5358CLWTR-T?

The C1 and C2 pins on the A5358CLWTR-T set photoamplifier gain for supervisory (push-to-test, chamber monitor) and standby modes respectively, using Ae = 1 + (C/10) where C is in pF. C1 typically uses 0.047 µF for high gain; C2 uses 4700 pF for low gain. A series resistor is required with C2 to stabilize gain switching.

Does the A5358CLWTR-T support hush functionality, and how is it configured?

Yes, the A5358CLWTR-T supports a 10-minute hush mode via the HUSH pin. When HUSH voltage exceeds 1.5 V and TEST is pulsed low, the device enters timer mode, reducing smoke sensitivity using a VDD–STROBE resistive divider. If hush is not needed, connect HUSH to VSS to disable the feature entirely.

What packaging and environmental ratings apply to the A5358CLWTR-T?

The A5358CLWTR-T is supplied in a 16-pin SOICW surface-mount package with Pb-free matte-tin leadframe plating. It is rated for continuous operation from –25°C to +75°C ambient temperature and meets EN 14604 and BS 5446-1 standards for residential and commercial smoke detection applications.