Microchip Technology RE46C114E8F

Overview

RE46C114E8F from Microchip Technology (via R&E International) is an ionization-type smoke detector IC designed for UL217-compliant residential and commercial smoke alarms. It interfaces directly with ionization chambers, provides guard-amplified DETECT input with ±0.75 pA leakage, delivers microprocessor-compatible analog VOUT (½×VDD or ½×DETECT), and operates from 6–12 V_DD and 2.7–5.5 V_CC with quiescent current <10 µA.

For engineers reviewing the RE46C114E8F datasheet, RE46C114E8F pinout, RE46C114E8F application, or RE46C114E8F equivalent, this device serves as a low-power, ESD-hardened (2000 V HBM), analog front-end for battery-powered smoke detection systems requiring precise chamber current sensing and dual-supply rail monitoring.

Technical Context

The RE46C114E8F integrates a precision guard amplifier driving G1/G2 terminals to suppress surface leakage at the ultra-low-current DETECT input, enabling reliable ionization chamber signal acquisition. Its SELECT-controlled output multiplexing allows dynamic switching between supply voltage (VDD) and chamber voltage (DETECT) monitoring via a single A/D input.

It employs CMOS technology with internal reverse-battery protection logic on VDD and operates across –10°C to +60°C ambient, meeting UL217 thermal stability requirements. The ±50 mV offset voltage and 10 kΩ output impedance ensure compatibility with standard 10 kΩ load resistors and 8- to 12-bit microcontroller ADCs.

Key Specifications

Pinout & Package

RE46C114E8F is packaged in an 8-lead PDIP (Plastic Dual In-line Package) with 0.3-inch body width and standard through-hole mounting footprint.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ionization smoke detector front-end applications.

Compared with RE46C124E8F and ISL28134IBZ, the RE46C114E8F uniquely balances UL217 readiness, sub-10 µA quiescent current, and integrated guard amplification-making it optimal for certified, battery-constrained ionization alarms without added test features or custom analog design overhead.

Availability

RE46C114E8F is available at Aetrix Electronics and suitable for residential smoke alarms, commercial ceiling-mounted detectors, and interconnected alarm systems requiring stable component supply, long-term lifecycle support, and UL217-compliant performance.

Supply support for RE46C114E8F 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 is a subsidiary of Microchip Technology Inc., specializing in safety-critical analog ICs for fire and life safety applications.

The RE46C114E8F belongs to Microchip's R&E smoke detector IC product line, engineered specifically for UL217-compliant ionization chamber interfacing with minimal external components and guaranteed low-leakage performance.

FAQ

What is the primary function of the RE46C114E8F in a smoke detection system?

The RE46C114E8F serves as the analog front-end interface between an ionization chamber and a microcontroller. It conditions the ultra-low-current DETECT signal, provides guard-driven leakage suppression via G1/G2 outputs, and delivers a ratiometric analog output (VOUT) that represents either half the VDD supply or half the DETECT voltage-depending on the SELECT input state. This enables reliable, low-power smoke sensing in UL217-certified devices.

Does the RE46C114E8F require external reverse-battery protection?

Yes, the RE46C114E8F requires external reverse-battery protection on the VDD pin. The datasheet explicitly states that "Reverse battery protection must be provided externally" due to the absence of internal polarity protection. A series Schottky diode or MOSFET-based protection circuit is commonly used to prevent damage when a 9 V battery is inserted incorrectly.

How does the SELECT pin affect the behavior of the RE46C114E8F?

The SELECT pin determines the source of the VOUT signal: when floating, VOUT is inactive and pulled to VSS (low-power mode); when driven low (VSS), VOUT = 0.5 × VDD; when driven high (VCC), VOUT = 0.5 × DETECT. This allows a single microcontroller ADC channel to monitor both battery voltage health and ion chamber status without additional analog switches or op amps.

What is the significance of the ±0.75 pA DETECT input leakage specification for the RE46C114E8F?

The ±0.75 pA DETECT input leakage ensures minimal error when measuring the femtoamp-level ion currents generated by smoke particles in the chamber. At this level, even minor PCB contamination or humidity-induced leakage would overwhelm the signal-so the RE46C114E8F's guarded architecture and ultra-low leakage enable stable, repeatable detection thresholds essential for UL217 compliance.

Can the RE46C114E8F operate with a 3.3 V microcontroller supply (VCC)?

Yes, the RE46C114E8F supports VCC from 2.7 V to 5.5 V, making it fully compatible with 3.3 V microcontrollers. When VCC = 3.3 V, the SELECT input high threshold is ~2.9 V (VCC − 0.4 V), and the low threshold remains ≤0.4 V-ensuring reliable TTL/CMOS logic-level compatibility. The guard amplifier and VOUT circuitry remain functional across this full VCC range.