Microchip Technology RE46C140SW16TF

Overview

RE46C140SW16TF from R&E International (a Microchip Technology subsidiary) is a CMOS photoelectric smoke detector ASIC with integrated interconnect, temporal horn pattern generation, and 10-minute timer-based sensitivity control. It delivers ultra-low standby current (4 µA at 9 V), supports push-button chamber testing via high-gain mode, and performs automatic low-battery and chamber-integrity checks every 43 seconds. It is UL217/UL268 recognized and designed for standalone or interconnected residential/commercial smoke alarms.

For engineers reviewing the RE46C140SW16TF datasheet, RE46C140SW16TF pinout, RE46C140SW16TF application, or RE46C140SW16TF equivalent, key selection considerations include its 16-pin SOIC-W package, strobe-driven 100 µs IRED pulsing, VDD-5 V regulated STROBE output, dual-gain photoamplifier (C1/C2 configurable), and IO pin bidirectional interconnect supporting up to 40 units - all critical for compliant, low-power, life-safety system design.

Technical Context

The RE46C140SW16TF integrates a dual-capacitor–programmable photoamplifier (C1 for test/high gain, C2 for standby/normal gain), an internal oscillator with 10.5 ms nominal period (TPOSC), and a pulsed STROBE output (VDD−5 V) that powers detection circuitry only during 100 µs sampling windows every 10 seconds in standby. Smoke detection triggers accelerated sampling (down to 1.0 s intervals) and three consecutive valid samples initiate local alarm.

Its bidirectional IO pin implements interconnect logic with 670 ms digital filtering, constant-current drive during local alarm, and 1-second NMOS discharge post-alarm. The 10-minute timer mode reconfigures the smoke comparator reference from internal VDD−3.5 V to external voltage on VSEN (Pin 15), enabling temporary sensitivity reduction without hardware modification.

Key Specifications

Pinout & Package

RE46C140SW16TF is housed in a 16-lead Wide SOIC (SOIC-W) package with 1.27 mm pitch, optimized for surface-mount assembly and thermal performance in smoke alarm enclosures.

Key Features

Applications

Equivalent & Alternatives

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

Compared with Allegro A5366 and ON Semiconductor NCS36510, the RE46C140SW16TF uniquely combines UL-recognized analog smoke sensing, hardware-based NFPA 72 horn timing, ultra-low 4 µA standby, and field-adjustable 10-minute sensitivity control - all in a single 16-pin SOIC-W device without external timing or microcontroller dependencies.

Availability

RE46C140SW16TF is available at Aetrix Electronics and suitable for residential fire safety systems, commercial interconnected alarm networks, kitchen-nuisance mitigation units, service-diagnostic smoke detectors, and UL217/UL268–certified OEM designs requiring stable component supply and long-lifecycle support.

Supply support for RE46C140SW16TF 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., specializes in highly integrated, safety-critical analog ICs for fire and life-safety applications.

The RE46C140SW16TF belongs to R&E's photoelectric smoke detector ASIC product line, engineered specifically to replace discrete analog front-ends and reduce certification effort in UL-listed smoke alarm designs.

FAQ

What is the operating supply voltage range for the RE46C140SW16TF?

The RE46C140SW16TF operates from 6 V to 12 V DC, covering standard 9 V alkaline and carbon-zinc batteries across their full discharge curve. Its internal low-battery detection threshold is fixed at 7.2 V (typical), ensuring reliable warning before end-of-life. This range eliminates the need for external regulators in most smoke alarm designs and maintains stable photoamplifier gain and oscillator timing across varying battery voltages.

How does the RE46C140SW16TF achieve ultra-low standby current?

The RE46C140SW16TF achieves 4 µA typical standby current (at 9 V) by powering down the entire analog smoke detection circuitry between 10-second sampling intervals. Only the internal oscillator and minimal bias circuitry remain active. During each 10-second cycle, it activates the STROBE output (VDD−5 V) for just 100 µs to energize the photodiode and photoamplifier, then performs a single comparison against the internal reference - minimizing energy per detection event.

What is the function of the VSEN pin (Pin 15) on the RE46C140SW16TF?

The VSEN pin on the RE46C140SW16TF serves exclusively as the external reference input for the smoke comparator during the 10-minute timer mode. When activated by a falling edge on the TEST pin, the device switches from its default internal VDD−3.5 V reference to the voltage applied to VSEN. This allows real-time, externally controlled sensitivity adjustment - for example, lowering detection threshold temporarily in kitchens - without modifying C1/C2 or requiring firmware.

Can the RE46C140SW16TF drive a piezoelectric horn directly?

Yes, the RE46C140SW16TF drives piezoelectric horns directly via complementary outputs HORNB (Pin 8) and HORNS (Pin 9), forming a full-bridge configuration. Each pin supports 16 mA sink/source, delivering the NFPA 72–compliant temporal pattern (500 ms ON / 1.5 s OFF) without external drivers. External components R10/R11/C6 (per Figure 2) optimize sound pressure level and impedance matching for common piezo elements.

Is the RE46C140SW16TF pin-compatible with other devices in its family?

The RE46C140SW16TF shares identical pinout and functionality with other RE46C140 variants in 16L W SOIC packaging (e.g., RE46C140SW16F), differing only in tape-and-reel vs. tube packaging and RoHS compliance markings. It is not pin-compatible with PDIP or narrow SOIC versions due to different thermal and mechanical footprints, though electrical behavior and register mapping remain consistent across all RE46C140 packages.