Microchip Technology RE46C168SW16F

Overview

RE46C168SW16F from Microchip Technology is a low-power CMOS photoelectric smoke detector ASIC with integrated interconnect, alarm memory, and programmable sensitivity timing. It delivers temporal horn pattern output (NFPA 72 compliant), 1.2-minute reduced-sensitivity timer mode, <8 µA quiescent current, and internal low-battery detection for UL217/UL268-compliant residential smoke alarms.

For engineers reviewing the RE46C168SW16F datasheet, RE46C168SW16F pinout, RE46C168SW16F application, or RE46C168SW16F equivalent, this page provides verified functional specifications, confirmed SOIC-16 package mapping, validated pin roles for interconnect and horn drive, and two manufacturer-confirmed alternative variants within the RE46C165/6/7/8 family.

Technical Context

The RE46C168SW16F implements a strobed photoamplifier architecture with dual-gain capacitor inputs (C1/C2) enabling chamber test and sensitivity control. Its internal oscillator drives IRED pulsing every 10 seconds in standby, reducing average current to <8 µA while maintaining smoke detection integrity.

It features bidirectional interconnect logic with digital filtering (≤300 ms pulse rejection), charge-dump discharge (0.99 s duration), and remote alarm delay of 0.37–0.81 s. The device supports Timer Mode via TEST/VSEN for 1.2-minute reduced-sensitivity operation per UL217 Annex D requirements.

Key Specifications

Pinout & Package

RE46C168SW16F is supplied in a 16-lead SOIC (150 mil) package with RoHS-compliant matte tin plating. Pin numbering follows standard SOIC convention (pin 1 = top-left corner, counterclockwise).

Key Features

Applications

Equivalent & Alternatives

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

Compared with RE46C168SW16F, RE46C167SW16F is functionally identical and interchangeable, while RE46C166SW16F trades NFPA 72 temporal compliance for faster horn cycling - making it unsuitable for UL217-certified installations requiring standardized evacuation signals.

Availability

RE46C168SW16F is available at Aetrix Electronics and suitable for residential smoke alarms, interconnected safety systems, and UL217-certified detector manufacturing requiring stable component supply, long-lifecycle assurance, and RoHS-compliant packaging.

Supply support for RE46C168SW16F 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

Microchip Technology Inc. is a U.S.-based semiconductor company specializing in microcontrollers, analog devices, and safety-critical ASSPs for industrial, automotive, and consumer applications.

The RE46C165/6/7/8 product line was designed specifically for photoelectric smoke detection systems complying with UL217 and UL268 standards, integrating all essential analog front-end, timing, and alarm functions into a single CMOS ASIC.

FAQ

What is the confirmed Timer Mode duration for RE46C168SW16F?

The RE46C168SW16F implements a 1.2-minute Timer Mode, as specified for the RE46C167/8 variant group in DS20002251B. This duration is factory-trimmed and production-tested, enabling temporary sensitivity reduction per UL217 Annex D without external components. The RE46C168SW16F shares identical timing behavior with RE46C167SW16F.

Does RE46C168SW16F support NFPA 72 temporal horn patterns?

Yes, RE46C168SW16F generates the NFPA 72-compliant temporal three-beep pattern (450–550 ms on / 450–550 ms off) directly from its HB/HS outputs. This is confirmed in the AC Electrical Characteristics table (THON1/THOF1 parameters) and Figure 3-2 of DS20002251B, distinguishing it from continuous-tone variants like RE46C166SW16F.

How does the interconnect function work on RE46C168SW16F?

The RE46C168SW16F uses its IO pin for bidirectional interconnect: during local alarm, it drives high via constant-current source; during standby, it monitors for remote-active signals with digital filtering (≤300 ms rejection). Charge dump discharges line capacitance for 0.99–1.46 s post-alarm, ensuring clean signal reset across up to 40 interconnected units.

What is the maximum number of detectors that can be interconnected using RE46C168SW16F?

RE46C168SW16F supports interconnection of up to 40 detectors, as explicitly stated in the Features section of DS20002251B. This capacity is enabled by the IO pin's 280 kΩ internal pull-down, robust ESD protection (>2000 V HBM), and charge-dump circuitry that maintains signal integrity across distributed wiring.

Is RE46C168SW16F compatible with both alkaline and carbon-zinc 9 V batteries?

Yes, RE46C168SW16F operates across 6–12 V and includes dedicated low-battery detection (6.9–7.5 V threshold). The datasheet specifies C3 capacitor scaling (1 µF for alkaline, ≥4.7 µF for carbon-zinc) to maintain stable VDD regulation - confirming design validation for both battery chemistries in UL217-certified deployments.