Allegro MicroSystems A5367CA-T

Overview

A5367CA-T from Allegro MicroSystems is a low-current BiCMOS integrated circuit designed specifically for ionization-type smoke detectors, featuring UL217/UL268 recognition, 125-unit interconnect capability, temporal horn pattern generation, and ultra-low standby current of 5.0 μA at 9 V. It integrates oscillator timing, piezoelectric horn drive (HORN1/HORN2), active guard amplifiers (GUARD1/GUARD2), and programmable sensitivity/low-battery thresholds for battery-powered safety systems.

For engineers reviewing the A5367CA-T datasheet, A5367CA-T pinout, A5367CA-T application, or A5367CA-T equivalent, this page delivers verified functional roles, real-world timing behavior (1.67 s standby cycle, 10 ms smoke sampling), UL-compliant alarm sequencing, and design-critical interface details for detector chamber integration, interconnect networking, and timer (Hush) mode implementation.

Technical Context

The A5367CA-T implements a strobed BiCMOS architecture that powers down all circuitry except the oscillator for 1.66 seconds between 10 ms smoke-sampling windows, achieving sub-μA average current draw. Its internal smoke comparator uses adjustable hysteresis (90–170 mV) and dual active guards to suppress surface leakage in ionization chambers.

Interconnect logic operates via open-drain I/O with charge-dump NMOS (1.33–1.99 s dump duration) and noise-immune latching requiring ≥93.9 ms high-level assertion to trigger remote alarms. Timer (Hush) mode enables 10.25-minute reduced-sensitivity periods via TIMER START edge detection and TIMER OUT pulldown control of SENSITIVITY SET.

Key Specifications

Pinout & Package

Package: 16-pin plastic dual in-line package (DIP), Pb-free with 100% matte tin leadframe plating, rated for –10°C to +60°C continuous operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with A5367CA-T, A5368CA-T trades 2.4× higher standby current for wider temperature tolerance, while SL185367 sacrifices UL recognition and active guarding for modularity-making A5367CA-T optimal for certified, low-power, high-reliability residential smoke alarms.

Availability

A5367CA-T is available at Aetrix Electronics and suitable for residential smoke alarm manufacturing, commercial building interconnect deployments, and battery-powered safety device development requiring stable component supply, long-lifecycle support, and UL217/UL268 compliance.

Supply support for A5367CA-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 semiconductor company specializing in magnetic sensing, precision power ICs, and safety-critical analog solutions for automotive and industrial markets.

The A5367CA-T belongs to Allegro's dedicated smoke detector IC product line, engineered to integrate all essential functions-ion chamber interface, UL-compliant timing, horn drive, and interconnect logic-into a single BiCMOS chip for certified, low-power, high-reliability life-safety systems.

FAQ

What is the standby current specification for A5367CA-T and how does it impact battery life?

The A5367CA-T draws 5.0 μA typical standby current at 9 V, enabling over 10 years of operation on a standard 9 V alkaline battery in smoke alarm applications. This ultra-low current is achieved through a 1.67 s power-down cycle with only 10 ms active sampling windows. The A5367CA-T's BiCMOS architecture minimizes leakage during sleep, and its internal oscillator ensures consistent timing without external components-directly supporting long-life, maintenance-free deployment required by UL217.

How does A5367CA-T implement UL217-compliant temporal horn patterns?

The A5367CA-T generates a precise temporal horn pattern-0.5 s on, 0.5 s off, 0.5 s on, 0.5 s off, 0.5 s on, 1.5 s off-during alarm conditions, fully compliant with UL217, NFPA72, and ISO8201 standards. This is implemented in hardware via internal timing logic synchronized to the 41.67 ms alarm oscillator period. The A5367CA-T drives piezoelectric horns directly through complementary HORN1/HORN2 outputs, eliminating need for external waveform generators while maintaining strict duty-cycle and silence-interval requirements mandated for certified audible alarms.

Can A5367CA-T be used with photoelectric smoke chambers?

No-the A5367CA-T is specifically optimized for ionization-type smoke chambers, with detector input circuitry (DETECT IN, GUARD1, GUARD2) calibrated for picoamp-level currents typical of ionization sources. Its comparator hysteresis, sensitivity adjustment range, and noise rejection architecture assume ion chamber characteristics. For photoelectric applications, Allegro offers dedicated ICs such as the A5369 series; substituting a photoelectric chamber with the A5367CA-T would result in unreliable trip thresholds and false alarms due to mismatched signal levels and response dynamics.

What is the purpose and behavior of the TIMER START and TIMER OUT pins on A5367CA-T?

The TIMER START pin initiates Timer (Hush) mode on a high-to-low edge, enabling a 10.25-minute period of reduced sensitivity to suppress nuisance alarms from cooking steam. During this time, the A5367CA-T pulls TIMER OUT low each smoke-sampling cycle, allowing an external resistor to lower the SENSITIVITY SET voltage and raise the trip threshold. The A5367CA-T continues monitoring-if smoke concentration increases sufficiently to exceed the reduced threshold, it triggers full alarm while Timer mode continues running to completion.

Does A5367CA-T require external components for basic operation, and which ones are mandatory?

Yes-the A5367CA-T requires four mandatory external components: a 0.1 μF low-leakage capacitor on OSC CAP (PTFE/polystyrene), an 8.2 MΩ resistor on TIMING RES, a piezoelectric horn connected across HORN1/HORN2, and a 9 V battery with reverse-polarity protection handled internally. Optional components include resistors on SENSITIVITY SET, LOW-V SET, and TIMER OUT for customization. The A5367CA-T integrates all active circuitry-including guards, comparators, oscillator, and drivers-so no external op-amps, timers, or logic gates are needed for UL217-compliant operation.