Microchip Technology RE46C143S16TF

Overview

RE46C143S16TF from R&E International (a Microchip Technology subsidiary) is a low-power CMOS photoelectric smoke detector ASIC with integrated interconnect capability, gain-selectable photo amplifier, 100 µs strobed detection every 8.1 s (standby), 75% duty-cycle horn driver, and UL217/UL268 recognition. It operates from 6–12 V, draws 4–8 µA standby current, and supports chamber integrity and low-battery testing every 40 s.

For engineers reviewing the RE46C143S16TF datasheet, RE46C143S16TF pinout, RE46C143S16TF application, or RE46C143S16TF equivalent, key selection considerations include interconnect scalability (up to 40 units), dual-gain photo amplifier configuration (C1/C2), STROBE-regulated VDD−5 V output, FEED input for feedback electrode interface, and IO bidirectional alarm propagation timing (750 ms filter, 1.2 s remote activation delay).

Technical Context

The RE46C143S16TF implements a pulsed photoelectric detection architecture: internal oscillator (nominal 10 ms period) powers analog circuitry only during brief 100 µs IRED pulses and 10 ms detection windows. Smoke presence triggers progressive reduction of inter-sample interval-from 8.1 s → 2.7 s → 1.33 s-requiring three consecutive valid samples to enter local alarm.

It integrates dual-path gain control (C1 for push-button test/chamber check; C2 for standby sensitivity), programmable low-battery threshold via LBSET resistor divider, and diagnostic mode reconfiguring IO/LBSET/FEED for calibration. Interconnect logic includes NMOS charge-dump discharge (~1.46 s), 600 ms input filtering, and supply-voltage-tolerant signaling (FEED: −10 V to +22 V).

Key Specifications

Pinout & Package

RE46C143S16TF is supplied in a 16-lead SOIC (Wide, 0.300" body width), RoHS-compliant, Pb-free package with standard JEDEC MS-013AC footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC145010P and SM5201-16, the RE46C143S16TF uniquely combines UL217/UL268 interconnect support, sub-5 µA standby, dual-gain chamber diagnostics, and production-ready diagnostic mode-making it the most integrated solution for new photoelectric alarm designs targeting North American markets.

Availability

RE46C143S16TF is available at Aetrix Electronics and suitable for residential smoke alarms, commercial fire alarm networks, and hardwired AC/DC safety modules requiring stable component supply, long-term lifecycle support, and UL-certified performance.

Supply support for RE46C143S16TF 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 wholly owned subsidiary of Microchip Technology Inc., specializing in safety-critical analog and mixed-signal ICs for fire and life safety applications.

The RE46C143 product line was designed specifically for photoelectric smoke detection systems requiring UL217/UL268 compliance, ultra-low power consumption, and scalable interconnect-targeting residential, commercial, and industrial alarm manufacturers.

FAQ

What is the standby current consumption of the RE46C143S16TF and how is it achieved?

The RE46C143S16TF achieves a typical standby current of 4 µA at 9 V by powering its analog detection circuitry only during brief 100 µs IRED pulses and 10 ms sampling windows every 8.1 seconds. This strobed architecture minimizes continuous bias current, enabling multi-year battery life in 9 V–powered smoke alarms. The internal oscillator and gain-selectable photo amplifier are key enablers of this ultra-low-power operation.

How does the RE46C143S16TF support interconnection of multiple smoke detectors?

The RE46C143S16TF supports interconnection of up to 40 detectors via its bidirectional IO pin, which drives high during local alarm and detects remote alarm signals with a 600 ms digital filter. An integrated NMOS discharge device activates for ~1.46 s after local alarm to clear line capacitance. The FEED input tolerates −10 V to +22 V, allowing interoperability with CO alarms and other voltage-tiered systems without external level-shifting.

What are the key differences between the C1 and C2 capacitor inputs on the RE46C143S16TF?

C1 sets the high-gain photo amplifier stage (A = 1 + C1/10 pF) used exclusively during push-to-test and chamber integrity checks, while C2 sets the normal-gain stage (A = 1 + C2/10 pF) active during standby smoke detection. This separation allows independent optimization: C1 enables reliable background reflection sensing for chamber diagnostics, and C2 tunes sensitivity to avoid nuisance alarms without compromising detection reliability.

Is the RE46C143S16TF certified for use in UL-listed smoke detectors?

Yes, the RE46C143S16TF is UL Recognized per File S24036 for use in smoke detectors complying with UL217 (residential) and UL268 (commercial) standards. Its integrated features-including interconnect logic, low-battery detection, chamber test, and 75% horn duty cycle-were validated as part of this certification, reducing time-to-market for OEMs developing UL-compliant products.

What is the function of the STROBE pin on the RE46C143S16TF and how is it used in the detection circuit?

The STROBE pin on the RE46C143S16TF provides a regulated VDD−5 V output that serves as the negative supply rail for the photo amplifier and IRED driver circuits during active detection periods. It is asserted only during the 100 µs IRED pulse and subsequent 10 ms sampling window, ensuring precise bias control and minimizing leakage paths. This regulated strobe enables stable gain and consistent smoke threshold detection across varying battery voltages.