Microchip Technology RE46C143SW16F

Overview

RE46C143SW16F from R&E International (a Microchip Technology subsidiary) is a CMOS photoelectric smoke detector ASIC with integrated interconnect functionality, low-power standby current (4 µA typical at 9 V), programmable gain photoamplifier (via external C1/C2), and UL217/UL268 recognition. It drives infrared emitters and piezoelectric horns in residential/commercial smoke alarms.

For engineers reviewing the RE46C143SW16F datasheet, RE46C143SW16F pinout, RE46C143SW16F application, or RE46C143SW16F equivalent, key selection criteria include interconnect scalability (up to 40 units), 75% horn duty cycle, chamber integrity self-test every 40 s, strobe-gated 100 µs IRED pulses, and compatibility with Motorola MC145010.

Technical Context

The RE46C143SW16F implements a dual-gain photoamplifier architecture: C2 sets normal standby gain (e.g., for smoke detection), while C1 enables high-gain mode during push-button test or chamber integrity check. Its internal oscillator controls periodic sampling-every 8.1 s in standby, accelerating to 336 ms during TEST activation.

It features bidirectional interconnect via open-drain IO pin with 500 ms digital filtering, constant-current drive for remote alarm propagation, and automatic charge dump (~1.46 s) post-alarm to discharge line capacitance. Horn output uses complementary HB/HS drivers for piezoelectric transducers with THON1 = 252 ms (typ) on-time and THOF1 = 84 ms (typ) off-time in local alarm.

Key Specifications

Pinout & Package

RE46C143SW16F is supplied in a 16-lead SOIC-W (Wide) package (body width 7.5 mm), RoHS-compliant and Pb-free.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC145010P and RE46C123SW16F, the RE46C143SW16F uniquely integrates UL-certified interconnect, dual-gain chamber testing, and sub-5 µA standby current-enabling compact, certified, battery-optimized designs without added discrete logic or firmware.

Availability

RE46C143SW16F is available at Aetrix Electronics and suitable for residential fire safety systems, commercial interconnected alarm networks, and battery-powered smoke detector modules requiring stable component supply, long-life operation, and UL217/UL268 compliance.

Supply support for RE46C143SW16F 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 analog and mixed-signal ASICs for safety-critical sensing applications.

The RE46C143SW16F belongs to R&E's smoke detector ASIC product line, engineered specifically for low-power, UL-recognized photoelectric smoke sensing with integrated interconnect and self-test capabilities in consumer and commercial fire alarm systems.

FAQ

What is the function of the STROBE pin on the RE46C143SW16F?

The STROBE pin on the RE46C143SW16F provides a regulated VDD−5 V output that powers the photoamplifier circuitry only during the 100 µs smoke sampling window. This gated power delivery is central to achieving the device's 4 µA typical standby current. In the RE46C143SW16F, STROBE is not a control signal but a precision low-noise supply rail synchronized to the internal oscillator, minimizing continuous power draw while maintaining signal integrity during detection.

How does the RE46C143SW16F perform chamber integrity testing?

The RE46C143SW16F performs chamber integrity testing every 40 seconds by switching the photoamplifier to high-gain mode using capacitor C1 and measuring background reflections in the optical chamber. If two consecutive tests fail-indicating dust accumulation, insect intrusion, or lens obstruction-the device triggers a distinct 10 ms horn chirp every 40 seconds, offset by 20 s from the low-battery chirp. This self-test is fully autonomous and requires no external microcontroller intervention in the RE46C143SW16F implementation.

What is the maximum number of RE46C143SW16F-based detectors that can be interconnected?

The RE46C143SW16F supports interconnection of up to 40 detectors on a single shared IO line, as specified in its UL217/UL268 recognition documentation. This scalability is achieved through low-leakage bidirectional IO pin design, internal pull-down, constant-current drive capability, and 1-second NMOS charge dump to manage line capacitance. Each RE46C143SW16F contributes minimal loading, enabling reliable signal propagation across the full 40-unit chain without external repeaters or level shifters.

Does the RE46C143SW16F require external components for basic operation?

Yes, the RE46C143SW16F requires external passive components for core functionality: capacitors C1 and C2 set photoamplifier gain; COSC and ROSC configure the internal oscillator period and IRED pulse width; resistors on LBSET define low-battery threshold; and an NPN transistor is needed to drive the infrared emitter from the IRED pin. The RE46C143SW16F integrates all signal conditioning, timing, logic, and output drivers-but relies on these minimal external elements to complete the smoke detection signal chain.

Is the RE46C143SW16F compatible with existing MC145010-based designs?

The RE46C143SW16F is pin-compatible and functionally compatible with the Motorola MC145010 in core smoke detection functionality, including photoamplifier interface, IRED drive, horn timing, and LED control. However, the RE46C143SW16F adds the IO interconnect pin, STROBE rail, and enhanced chamber test features-requiring minor PCB layout updates (e.g., adding IO routing and C1/C2 caps) but no redesign of the optical chamber or transducer interface. Migration preserves existing firmware-free operation while adding UL-recognized interconnect.