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Allegro MicroSystems A5348CA-T
- Part No.:
- A5348CA-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- Sensor and Detector Interfaces
- Package:
- 16-DIP (0.300", 7.62mm)
- Datasheet:
-
A5348CA-T.pdf
- Description:
- IC SMOKE DETECTOR ION 16DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,283
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Product details
Overview
A5348CA-T from Allegro MicroSystems is a discontinued BiCMOS ionization smoke detector IC with integrated interconnect, timer (Hush) mode, piezoelectric horn driver, and ultra-low standby current (5.0 μA typical at 9 V). It operates over –10°C to 60°C in a 16-pin DIP package and enables networking of up to 125 units for synchronized alarm response in residential fire safety systems.
For engineers reviewing the A5348CA-T datasheet, A5348CA-T pinout, A5348CA-T application, or A5348CA-T equivalent, key selection considerations include its discontinued status, 10 ms smoke-sensing window per 1.67 s cycle, active guard inputs (GUARD1/GUARD2), programmable low-battery threshold via LOW-V SET, and dual horn outputs (HORN1/HORN2) with 160 ms on-time during alarm.
Technical Context
The A5348CA-T integrates a strobed oscillator that powers the circuit for only 10 ms every 1.67 s in standby, reducing average current to ≤9.0 μA. Its smoke detection logic compares DETECT IN voltage against a user-adjustable SENSITIVITY SET reference, with built-in 130 mV hysteresis to suppress false alarms.
Interconnect functionality uses the bidirectional I/O pin with 3 s propagation delay and 93.9 ms noise-immune latching; Timer (Hush) mode is triggered by TIMER START edge and sustains reduced sensitivity for 10.25 minutes via TIMER OUT–driven resistor coupling to SENSITIVITY SET.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Current (Standby) | 5.0 μA typical at 9 V - enables >10-year battery life in 9 V-powered smoke detectors |
| Oscillator Period (No Smoke) | 1.67 s - defines ultra-low-power duty cycling interval for periodic smoke sampling |
| Horn Output On-Time | 160 ms - drives piezoelectric transducers with sufficient acoustic energy for audible alarm |
| Hysteresis Voltage | 130 mV typical - prevents oscillation near trip point and reduces nuisance alarms |
| Interconnect Capacity | Up to 125 units - supports whole-home or multi-unit alarm synchronization without external bus controller |
| Operating Temperature | –10°C to 60°C - validated for indoor residential environments including attics and garages |
| Low-Battery Threshold | 7.2–7.8 V - configurable via external resistor on LOW-V SET to match battery discharge profile |
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 ambient operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - TIMER START | Edge-triggered input | Starts 10.25-minute Timer (Hush) mode on high-to-low transition; disables sensitivity adjustment during alarm |
| 2 - I/O | Bidirectional interconnect node | Drives high (after 3 s delay) to trigger remote alarms; accepts high signal to accelerate local oscillator to 41.7 ms period |
| 3 - LOW-V SET | Analog threshold adjust | Resistor-to-VSS/VDD sets low-battery detection voltage between 7.2 V and 7.8 V for aging compensation |
| 4 - TIMER OUT | Open-drain output | Pulled low during Timer mode to reduce sensitivity via external resistor to SENSITIVITY SET pin |
| 5 - LED | Current-limited output | Sinks 10 mA to drive indicator LED with programmable pulse timing (8–48 s off-intervals) |
| 6 - VDD | Positive supply | Accepts 6–12 V DC; internal reverse-battery protection prevents damage from incorrect installation |
| 7 - TIMING RES | Bias resistor input | 8.2 MΩ resistor sets internal bias current, controlling oscillator timing accuracy and stability |
| 8 - FEEDBACK | Horn feedback input | Connects to piezoelectric horn terminal to enable closed-loop drive and prevent overvoltage stress |
| 9 - VSS | Negative supply | Ground reference for all analog and digital circuitry; shared return for horn, LED, and detector paths |
| 10 - HORN1 | Complementary horn output | Drives one side of push-pull piezoelectric horn configuration; VOH = 8.8 V, VOL = 0.5 V at 16 mA |
| 11 - HORN2 | Complementary horn output | Drives opposite side of push-pull horn; phase-inverted relative to HORN1 for maximum acoustic output |
| 12 - OSC CAP | Oscillator timing capacitor | 0.1 μF low-leakage capacitor (PTFE/polystyrene) sets 1.67 s standby period and 41.7 ms alarm period |
| 13 - SENSITIVITY SET | Smoke trip reference | Resistor divider adjusts trip voltage from 48.5% to 51.5% of VDD to match chamber ionization characteristics |
| 14 - GUARD1 | Active guard amplifier | Maintains voltage within ±100 mV of DETECT IN to minimize surface leakage on PCB traces near ion chamber |
| 15 - DETECT IN | Ion chamber input | High-impedance (±1.0 pA input current) node for connecting ionization chamber anode; protected by internal ESD diodes |
| 16 - GUARD2 | Active guard amplifier | Second guard amplifier adjacent to DETECT IN; provides redundant leakage suppression for critical safety applications |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low standby current | 5.0 μA typical enables >10-year operation on a single 9 V alkaline battery in residential smoke detectors |
| Programmable Timer (Hush) mode | 10.25-minute duration with external resistor coupling allows temporary desensitization for cooking steam or dust |
| Dual active guard inputs | GUARD1 and GUARD2 maintain ±100 mV tracking of DETECT IN to eliminate surface leakage-induced false alarms |
| Interconnect noise immunity | 93.9 ms I/O high-time requirement prevents spurious triggering from EMI or contact bounce in wired interconnect |
| Integrated low-battery test | Automated check every ~40 seconds using internal reference; LED pulse indicates status without external circuitry |
Applications
| Residential Smoke Alarms | Multi-Unit Interconnected Systems |
|---|---|
|
Use Scenario: Standalone ceiling-mounted ionization smoke detector powered by 9 V battery in bedrooms or hallways. IC Role / Device Role / Timing Role: Primary smoke sensing and alarm generation IC; performs 10 ms smoke sampling every 1.67 s and drives piezoelectric horn during alarm. Use Value: 5.0 μA standby current extends battery life beyond 10 years, eliminating frequent replacements and maintenance calls. |
Use Scenario: Networked smoke detectors across multiple floors of a home, wired in parallel via I/O pins. IC Role / Device Role / Timing Role: Distributed alarm coordinator; detects local smoke and asserts I/O high to trigger synchronized alarms in all connected units. Use Value: 125-unit interconnect capacity and 3 s propagation delay ensure whole-home alerting without central controller or firmware updates. |
| Kitchen Nuisance Alarm Mitigation | Commercial Retrofit Installations |
|
Use Scenario: Smoke detector installed near kitchen where steam or cooking aerosols cause false alarms. IC Role / Device Role / Timing Role: Timer (Hush) mode initiator; TIMER START input triggers 10.25-minute reduced-sensitivity period. Use Value: External resistor from TIMER OUT to SENSITIVITY SET lowers trip threshold temporarily, suppressing alarms from non-hazardous particulates. |
Use Scenario: Replacement of legacy smoke alarm modules in existing building infrastructure with minimal wiring changes. IC Role / Device Role / Timing Role: Drop-in functional replacement for prior-generation ionization detector ICs using identical 16-pin DIP footprint and pinout. Use Value: Pin-compatible design and same VDD/VSS/OSC CAP/DETECT IN interface allow direct PCB-level substitution without layout revision. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar ionization smoke detector applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| A5347CA-T | Lower interconnect capacity (up to 32 units); no TIMER OUT pin; fixed 8-minute Timer mode | Lacks programmable sensitivity reduction during Timer mode; suitable only for basic hush functionality | Select when network size is limited and full 125-unit scalability is unnecessary |
| SL18-1200 | Discrete analog smoke detector ASIC; no integrated horn driver; requires external MOSFET for alarm output | Higher BOM count and board space; lacks built-in I/O interconnect logic and active guard amplifiers | Choose only if legacy design reuse mandates identical analog architecture and external drive flexibility |
Compared with A5348CA-T, A5347CA-T offers reduced interconnect scale and fixed timer duration but retains core low-power operation, while SL18-1200 requires external components for horn drive and interconnect, increasing design complexity and validation effort for new safety-critical deployments.
Availability
A5348CA-T is available at Aetrix Electronics and suitable for residential fire alarm systems, interconnected multi-unit safety networks, and commercial retrofit installations requiring stable component supply despite its discontinued status.
Supply support for A5348CA-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 of high-performance magnetic sensors, power ICs, and precision analog semiconductors for automotive, industrial, and consumer safety applications.
The A5348CA-T belongs to Allegro's dedicated smoke detector IC product line, engineered specifically for ultra-low-power, high-reliability ionization-based fire detection with integrated interconnect and user-controllable hush functionality.
FAQ
Is the A5348CA-T still recommended for new designs?
No, the A5348CA-T is officially discontinued and not recommended for new designs. Allegro MicroSystems declared it obsolete on May 17, 2023, and samples are no longer available. For new projects, engineers should evaluate current-generation alternatives such as the A5347CA-T or consult Allegro's factory for approved replacements. The A5348CA-T remains supported for legacy production and repair of existing certified smoke alarm units.
What is the function of the GUARD1 and GUARD2 pins on the A5348CA-T?
The GUARD1 and GUARD2 pins on the A5348CA-T are active guard amplifier outputs that track the DETECT IN voltage within ±100 mV. They surround the high-impedance ion chamber input to suppress surface leakage currents on the PCB, which is critical for maintaining detection accuracy and avoiding false alarms. Unlike passive guarding, these pins provide continuous, un-strobed bias-ensuring protection even during the 1.66-second power-down intervals of the A5348CA-T's ultra-low-power operation.
How does the A5348CA-T achieve its 5.0 μA standby current specification?
The A5348CA-T achieves 5.0 μA typical standby current through aggressive power gating: its internal oscillator enables full circuit operation for only 10 ms every 1.67 s, and all analog blocks-including the smoke comparator, guard amplifiers, and reference circuits-are powered down between samples. The BiCMOS process minimizes leakage, and the TIMING RES pin's 8.2 MΩ bias resistor further reduces quiescent draw. This architecture directly enables >10-year battery life in 9 V–powered smoke detectors without compromising detection reliability.
Can the A5348CA-T drive a piezoelectric horn directly without external components?
Yes, the A5348CA-T can drive a piezoelectric horn directly using its complementary HORN1 and HORN2 outputs, which deliver 16 mA sink/source capability with VOH = 8.8 V and VOL = 0.5 V at 9 V supply. The FEEDBACK pin enables closed-loop control to prevent overvoltage stress. No external MOSFETs or drivers are required-only proper impedance matching via the horn's datasheet-specified series resistor (typically 200 Ω to 330 Ω) and correct capacitor selection (0.001 µF) on the TIMER START line for reliable hush activation.
What does "discontinued" mean for long-term supply of the A5348CA-T?
"Discontinued" means Allegro MicroSystems has ceased manufacturing the A5348CA-T, and no new production lots will be released. However, Aetrix Electronics maintains traceable inventory of genuine, factory-original A5348CA-T units for legacy support. Supply support includes BOM continuity management and lifecycle coordination-ensuring availability for repair, replacement, and certified end-of-life production runs, subject to remaining stock levels and contractual allocation agreements.
A5348CA-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Package/Case:
- 16-DIP (0.300", 7.62mm)
- Series:
- -
- Packaging:
- Tube
- Product Status:
- Not For New Designs
- Programmable:
- Not Verified
- Type:
- Smoke Detector
- Input Type:
- Ionization
- Output Type:
- Voltage
- Current - Supply:
- 12 µA
- Operating Temperature:
- -10°C ~ 60°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 16-DIP
A5348CA-T FAQ
1.How can I place an order for A5348CA-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A5348CA-T on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for A5348CA-T reliable?
The price and inventory of A5348CA-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A5348CA-T is usually 5 days.
3.What payment methods are accepted for A5348CA-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A5348CA-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A5348CA-T?
A5348CA-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A5348CA-T order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for A5348CA-T?
For technical support, including A5348CA-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A5348CA-T requirements.
6.How does Aetrix verify that A5348CA-T is sourced from the original manufacturer or authorized distributors?
All A5348CA-T products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that A5348CA-T meets industry standards.
7.What is the process for return or replacement of A5348CA-T?
All A5348CA-T units undergo pre-shipment inspection (PSI). If there is an issue with A5348CA-T, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The A5348CA-T part is unused and in its original packaging.
Return procedure for A5348CA-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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