A5366CA-T

Overview

The A5366CA-T is a low-current BiCMOS integrated circuit designed for photoelectric smoke detectors. It interfaces with an infrared chamber to detect scattered light from smoke particles and supports interconnecting up to 50 units for synchronized alarms. The device operates on a 6 V to 12 V supply, drawing an average standby current of 9 μA. It features a variable-gain photoamplifier, internal timing circuits, and a piezoelectric horn driver. The component is housed in a 16-pin DIP package (suffix A) with lead-free matte-tin plating (suffix –T). It is rated for continuous operation between –25°C and 75°C.

Feature Summary

• Supports networking of up to 50 interconnected detectors for synchronized alarm activation.
• Includes a built-in piezoelectric horn driver capable of generating temporal horn patterns compliant with UL217, NFPA72, and ISO8201 standards.
• Features internal low-battery detection and periodic chamber sensitivity monitoring to signal degraded conditions.
• Incorporates a three-stage speedup sensing scheme and noise filtering to minimize false triggering.

Applications

• Photoelectric smoke detector systems
• Interconnected fire alarm networks
• Stand-alone residential smoke alarms

Procurement Notes

Verify the specific ordering suffix to confirm the package type and lead finish. The CA-T designation indicates a 16-pin through-hole DIP package with lead-free matte-tin plating. Confirm that the procurement channel provides the official datasheet and ensures compliance with the specified operating temperature range of –25°C to 75°C for the intended application environment.

Selection Notes

Select this component when designing a photoelectric smoke detector requiring networked alarm capabilities and low standby power consumption. Ensure the external circuitry accommodates the 6 V to 12 V supply range and includes necessary components for the variable-gain photoamplifier. Verify that the application utilizes a 16-pin DIP footprint compatible with the Package A dimensions provided in the datasheet.

Part Context

The A5366CA-T belongs to the A5366 series of smoke detector ICs manufactured by Allegro MicroSystems. This series provides specialized solutions for both ionization and photoelectric smoke detection technologies. The A5366 specifically addresses photoelectric applications with integrated timer and interconnect functions, distinguishing it from other sensor or driver families within the manufacturer's portfolio.

Replacement Considerations

The A5366CLWTR-T serves as a surface-mount alternative within the same family, utilizing a 16-pin SOICW package instead of the DIP configuration. Designers transitioning from DIP to surface mount must account for differences in thermal resistance and PCB layout requirements while maintaining functional compatibility.

FAQ

How does the A5366 handle false triggering during local alarms?

During a local alarm, the internal gain of the photoamplifier increases by approximately 10% to reduce false triggering. Additionally, the I/O input requires three consecutive high samples plus one additional cycle to trigger an alarm from a remote unit, providing significant immunity to noise.

What is the function of the HUSH pin in standby mode?

The HUSH pin enables or disables the internal 10-minute 'hush' timer mode. When the voltage exceeds 1.5 V, timer mode is enabled, allowing reduced sensitivity to nuisance alarms. If connected to VSS or left open with less than 0.5 V, timer mode is disabled.

How is the diagnostic test/calibration mode initiated?

This mode is initiated by pulling the TEST pin below VSS by continuously drawing 400 μA from the pin for at least one clock cycle on OSC CAP. In this mode, certain pins are reconfigured to facilitate calibration of the IC and assembled detector.