Microchip Technology RE46C100D8F

Overview

RE46C100D8F from Microchip Technology is a CMOS piezoelectric horn driver IC designed for self-oscillating and direct-drive alarm applications. It integrates feedback control, push-pull output stage, and horn enable logic, with <100 nA quiescent current, 20 Ω typical R_ON at 9 V, and operation from 6–16 V - enabling ultra-low-power battery-operated smoke and CO detectors.

For engineers reviewing the RE46C100D8F datasheet, RE46C100D8F pinout, RE46C100D8F application, or RE46C100D8F equivalent, key selection considerations include its dual-mode horn drive capability (self-oscillating via FEED pin or external signal input), HRNEN-active-high enable timing, and thermal performance in 2×3 mm DFN with exposed pad - critical for compact, long-life safety devices.

Technical Context

The RE46C100D8F implements a dedicated analog push-pull output stage driving HORNB and HORNS complementary outputs to excite piezoelectric transducers. Its internal feedback path accepts signals from the horn's feedback electrode via the FEED pin, enabling self-oscillation without external oscillator components.

Logic-level HRNEN control (V_IL ≤ 1 V, V_IH ≥ 2.3 V) directly gates the output stage, allowing PWM modulation of audible alerts. The device operates across –40°C to +85°C and supports wide supply range (6–16 V), with FEED pin rated to –10 V to +22 V for robust feedback interface handling.

Key Specifications

Pinout & Package

RE46C100D8F uses an 8-lead 2×3 mm DFN package with exposed thermal pad (EP), optimized for low-profile, high-reliability alarm modules. The EP must be soldered to VSS for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar piezoelectric horn driver applications.

Compared with RE46C100E8F and RE46C100S8F, the RE46C100D8F offers the lowest thermal resistance (75°C/W) and smallest footprint - making it optimal for space-constrained, high-volume smoke detector modules where thermal management and PCB area are critical.

Availability

RE46C100D8F is available at Aetrix Electronics and suitable for smoke detectors, CO detectors, and personal security alarms requiring stable component supply, long-lifecycle support, and RoHS-compliant lead-free packaging.

Supply support for RE46C100D8F 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 leading provider of microcontrollers, analog devices, and timing solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The RE46C100D8F belongs to Microchip's safety ASIC product line, engineered specifically for ultra-low-power, high-reliability audible alarm functions in life-safety equipment - emphasizing quiescent current minimization, piezo interface robustness, and qualification across extended temperature ranges.

FAQ

What is the function of the FEED pin on the RE46C100D8F?

The FEED pin on the RE46C100D8F serves a dual role: in self-oscillating mode, it connects to the feedback electrode of a three-terminal piezoelectric horn to sustain oscillation; in direct-drive mode, it accepts an external square-wave signal to drive two-terminal horns. Its –10 V to +22 V rating protects against piezo-induced voltage spikes, ensuring reliable operation without clamping diodes in the RE46C100D8F circuit.

Can the RE46C100D8F drive both two-terminal and three-terminal piezoelectric horns?

Yes, the RE46C100D8F supports both configurations. For three-terminal self-oscillating horns, the FEED pin is connected to the feedback electrode through a current-limiting resistor. For two-terminal horns, FEED acts as an external signal input, while HRNEN enables/disables the output stage. This flexibility allows a single RE46C100D8F design to serve multiple horn types without hardware changes.

What is the purpose of the exposed thermal pad (EP) on the RE46C100D8F DFN package?

The exposed thermal pad (Pin 9, EP) on the RE46C100D8F DFN package provides a low-thermal-resistance path from the die to the PCB ground plane. It must be soldered to VSS for effective heat dissipation - reducing junction temperature by up to 30°C versus non-connected EP - and also improves electrical noise immunity. Microchip specifies EP connection as mandatory for reliable RE46C100D8F operation in continuous-tone applications.

How does the HRNEN pin control the output of the RE46C100D8F?

The HRNEN pin on the RE46C100D8F is an active-high enable input: logic high (≥2.3 V) activates the push-pull output stage on HORNB and HORNS, while logic low (≤1 V) disables output and places both pins in high-impedance state. This allows precise timing control - including PWM modulation of tone duration - and eliminates audible click noise during enable/disable transitions in the RE46C100D8F application.

Is the RE46C100D8F compatible with 3.3 V logic systems?

No, the RE46C100D8F is not directly compatible with 3.3 V logic. Its HRNEN input requires V_IH ≥ 2.3 V minimum, but the device itself operates from 6–16 V supply and lacks internal level-shifting. Driving HRNEN from a 3.3 V MCU GPIO may result in marginal or unreliable enable behavior. A simple N-channel MOSFET level shifter or buffer is recommended to ensure robust RE46C100D8F activation in mixed-voltage systems.