Microchip Technology RE46C128E16F

Overview

RE46C128E16F from R&E International (a Microchip Technology subsidiary) is a CMOS ionization smoke detector ASIC with interconnect capability, designed for standalone or networked residential/commercial smoke alarms. It integrates low-power smoke sensing (±0.75 pA detect input), temporal horn pattern generation per NFPA 72, internal low-battery detection (7.2–7.8 V threshold), and interconnect support for up to 40 units. Its 16-pin SOIC package enables compact PCB layout in UL217/UL268-compliant detectors.

For engineers reviewing the RE46C128E16F datasheet, RE46C128E16F pinout, RE46C128E16F application, or RE46C128E16F equivalent, key selection criteria include its 6.5 µA standby current, guard-amplifier–enabled ion chamber interface, IO-driven remote alarm synchronization, and UL recognition under File S24036 - all critical for certified, battery-operated life-safety systems.

Technical Context

The RE46C128E16F employs a strobed architecture: its internal oscillator powers detection circuitry for 10.5 ms every 1.66 s, minimizing quiescent current. Smoke sampling occurs only during active strobes, while low-battery checks run every 40 s using the same LED driver path.

Its dual-guard amplifier outputs (GUARD1/GUARD2) actively track the DETECT input within ±50 mV to suppress surface leakage, and the IO pin functions bidirectionally - driving high during local alarm to trigger interconnected units, or accepting filtered external alarm signals (1000 ms digital filter) from CO or other detectors.

Key Specifications

Pinout & Package

RE46C128E16F is supplied in a 16-lead narrow SOIC (N SOIC) package, 7.5 mm × 10.3 mm body, 1.27 mm pitch, RoHS-compliant and Pb-free capable.

Key Features

Applications

Equivalent & Alternatives

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

Compared with RE46C128E16P and Allegro A5364, the RE46C128E16F uniquely combines SOIC packaging for SMT scalability, built-in NFPA 72 horn timing, and UL File S24036 recognition - reducing BOM count, layout area, and certification effort in volume-manufactured smoke alarms.

Availability

RE46C128E16F is available at Aetrix Electronics and suitable for residential fire alarm systems, commercial building life-safety networks, and UL-certified retrofit detector modules requiring stable component supply and long-term lifecycle support.

Supply support for RE46C128E16F 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

R&E International, acquired by Microchip Technology Inc. in 2006, specializes in highly integrated analog/mixed-signal ICs for safety-critical sensing applications.

The RE46C128 product line was engineered specifically for UL-listed ionization smoke detectors - integrating guarded sensing, ultra-low-power strobing, and temporal alarm generation to eliminate external components and simplify certification.

FAQ

What is the operating temperature range for the RE46C128E16F?

The RE46C128E16F is specified for operation from –10°C to +60°C ambient temperature, matching the environmental requirements of indoor residential and commercial smoke alarm installations. This range ensures reliable smoke detection performance across seasonal variations and typical HVAC-controlled building environments. The device's internal comparators and oscillators are characterized across this full range, with low-battery detection thresholds guardbanded to maintain accuracy at temperature extremes.

Does the RE46C128E16F require external passive components to function?

Yes, the RE46C128E16F requires three essential external components: a 0.1 µF low-leakage capacitor on OSCAP (pin 12) for oscillator timing, an 8.2 MΩ resistor on RBIAS (pin 6) for current setting, and a piezoelectric transducer connected between HS (pin 7) and HB (pin 8) for horn output. Additional optional resistors on VSEN (pin 13) and LBADJ (pin 3) enable threshold calibration. No external microcontroller or timing IC is needed due to its fully integrated architecture.

How does the RE46C128E16F implement interconnect functionality with other smoke detectors?

The RE46C128E16F implements interconnect via its IO pin (pin 2), which operates bidirectionally: during local alarm, it drives high to trigger interconnected units; when configured as an input, it accepts external alarm pulses through a 1000 ms hardware digital filter. This allows daisy-chaining up to 40 detectors on a single wire while rejecting noise or short glitches. The internal sink driver discharges the line after alarm exit, ensuring clean signal transitions without external pull-downs.

Is the RE46C128E16F compatible with both ionization and photoelectric smoke chambers?

The RE46C128E16F is specifically designed and optimized for ionization-type smoke chambers, with a ±0.75 pA detect input sensitivity and guard amplifier architecture tailored to their ultra-low-current output. It is not intended for use with photoelectric chambers, which typically produce higher current signals and require different amplification and filtering. Using it with photoelectric sensors would result in improper threshold detection and potential failure to meet UL217 requirements.

What UL standards does the RE46C128E16F support, and how is compliance verified?

The RE46C128E16F is UL Recognized under File S24036 for compliance with UL217 (Standard for Single and Multiple Station Smoke Alarms) and UL268 (Standard for Smoke Detectors). This recognition covers the IC's internal circuitry, including its temporal horn pattern, low-battery detection, and interconnect behavior. Compliance is verified through component-level testing by UL, and end-product manufacturers must still validate full-system performance - but the RE46C128E16F's recognition significantly reduces certification burden for final detector assemblies.