Allegro MicroSystems A5366CA

Overview

A5366CA from Allegro MicroSystems is a BiCMOS photoelectric smoke detector IC with integrated photoamplifier, strobe driver, IRED control, piezoelectric horn interface, interconnect logic, and UL217/UL268-compliant temporal alarm pattern generation. It operates from 6–12 V, draws only 12 μA average standby current, supports up to 50-unit networking, and delivers calibrated smoke detection in residential and commercial fire-safety systems.

For engineers reviewing the A5366CA datasheet, A5366CA pinout, A5366CA application, or A5366CA equivalent, this page provides verified technical context, UL-recognized functional specifications, validated 16-pin DIP package mapping, real-world timing behavior (e.g., 100 μs smoke sampling every 10 s), and confirmed alternatives for smoke detector design and replacement.

Technical Context

The A5366CA implements a three-stage speedup sensing scheme that requires two consecutive degraded sensitivity cycles before issuing a chirp warning and mandates three valid smoke samples before triggering full alarm - reducing false alarms while maintaining rapid response. Its variable-gain photoamplifier uses external C1 (0.047 μF) and C2 (4700 pF) capacitors to switch between supervisory (high-gain) and standby (low-gain +10% post-alarm) modes under precise internal timing control.

Internal oscillator sets core timing: nominal 10.4 ms period (t_osc), 105 μs IRED pulse width (t_high), and synchronized 9.5–11.5 ms STROBE/LED pulse widths. The I/O pin supports noise-immune interconnect via 42 ms sampling intervals and 95–137 ms high-level persistence requirement to prevent spurious remote alarms.

Key Specifications

Pinout & Package

Package: 16-pin plastic dual in-line package (DIP), through-hole mount, Pb-free option available (suffix –T). Thermal resistance R_θJA = 38°C/W on 4-layer JEDEC PCB.

Key Features

Applications

Equivalent & Alternatives

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

Compared with A5366CLWTR-T, the A5366CA offers identical electrical and functional behavior but in a through-hole DIP package optimized for prototyping and low-volume assembly; compared with SL1301, the A5366CA eliminates external timing and control circuitry, reduces qualification effort via UL file #S2113, and enables faster time-to-market for certified smoke alarms.

Availability

A5366CA is available at Aetrix Electronics and suitable for residential fire-safety systems, commercial building alarm networks, multi-unit housing interconnects, and serviceable detector modules requiring stable component supply and long-lifecycle support.

Supply support for A5366CA 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 semiconductor company specializing in magnetic sensing, motor driver, and safety-critical analog ICs, headquartered in Worcester, Massachusetts.

The A5366CA belongs to Allegro's photoelectric smoke detector IC product line, engineered specifically to integrate UL217/UL268-compliant signal conditioning, interconnect logic, and temporal alarm generation into a single BiCMOS device for battery-operated life-safety applications.

FAQ

What is the operating voltage range for the A5366CA?

The A5366CA operates from 6 V to 12 V DC referenced to VSS. This range accommodates standard 9 V alkaline batteries across their full discharge curve - including down to the 6.9–7.5 V low-battery threshold where the device initiates chirp warnings. Operation outside this range may damage the IC or invalidate UL recognition.

How does the A5366CA achieve UL217 and UL268 compliance?

The A5366CA is UL Recognized under file #S2113 for use in smoke alarms complying with UL217 (residential) and UL268 (commercial) standards. Compliance is achieved through on-die temporal horn pattern generation, three-stage smoke confirmation logic, built-in low-battery and chamber degradation detection, and validated 100 μs/10 s sampling architecture - all verified by Underwriters Laboratories.

Can the A5366CA drive a piezoelectric horn directly?

Yes, the A5366CA drives self-resonating piezoelectric horns directly via HORN1, HORN2, and FEEDBACK pins. It generates the full UL217 temporal pattern (0.5/0.5/0.5/0.5/0.5/1.5 s) without external components. External passive components (e.g., 8.2 kΩ resistor, 22 Ω series resistor) are required per the typical application diagram to match horn impedance and ensure reliable startup.

What is the purpose of the C1 and C2 pins on the A5366CA?

C1 and C2 set photoamplifier gain for different operational modes: C1 (0.047 μF typical) configures high gain during push-to-test and chamber monitoring; C2 (4700 pF typical) sets low gain during standby. Gain is calculated as A_e = 1 + C/10 pF. The A5366CA internally switches between them and boosts C2 gain by ~10% after local alarm detection to reduce false triggers.

Does the A5366CA support interconnection with other smoke detectors?

Yes, the A5366CA supports wired interconnection of up to 50 units via its I/O pin. When any unit detects smoke, it drives I/O high, triggering alarms in all connected devices. The I/O interface includes hardware noise filtering requiring 95–137 ms of sustained high level to register - preventing false alarms from EMI or contact bounce in shared wiring.