STMicroelectronics STM6321MWY6F

Overview

STM6321MWY6F from STMicroelectronics is a 5-pin precision voltage supervisor IC with integrated watchdog timer and manual reset input, designed for microprocessor power monitoring in industrial embedded systems. It monitors VCC at 3.3 V (±2.5%), asserts active-low open-drain RST for ≥1.4 ms upon fault detection, guarantees reset assertion down to VCC = 1.0 V, and features 1.6 s watchdog timeout and 3 µA typical supply current.

For engineers reviewing the STM6321MWY6F datasheet, STM6321MWY6F pinout, STM6321MWY6F application, or STM6321MWY6F equivalent, this page delivers verified technical context, exact pin functions, real-world use cases in MCU reset management, and validated alternative options for design flexibility and supply continuity.

Technical Context

The STM6321MWY6F implements a precision bandgap reference and comparator to monitor VCC against a fixed 3.3 V threshold (±2.5% over –40 to +85 °C), with guaranteed reset assertion down to VCC = 1.0 V. Its internal watchdog timer triggers reset if WDI remains static for ≥1.6 s (typ.), and clears on any WDI edge (≥50 ns pulse width).

Reset output is active-low open-drain (RST), requiring an external pull-up resistor (e.g., 10 kΩ) to any supply ≤6 V. The MR input includes a 52 kΩ internal pull-up and accepts TTL/CMOS logic or momentary switch-to-ground activation, asserting reset for trec (1.4 ms typ.) after MR release.

Key Specifications

Pinout & Package

STM6321MWY6F is housed in a standard 5-pin SOT23-5 package (JEDEC MO-178AA), with 1.3 mm max height, 2.9 mm × 1.6 mm footprint, and gull-wing leads for surface-mount assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar microprocessor supervisor applications.

Compared with MAX6321US33D3+, STM6321MWY6F offers open-drain flexibility for multi-source reset buses; versus TPS3808G33DBVR, it delivers the exact 1.4 ms pulse needed for legacy and cost-optimized MCUs, trading threshold precision for timing compliance and industrial temperature robustness.

Availability

STM6321MWY6F is available at Aetrix Electronics and suitable for industrial PLC controllers, smart meter firmware supervision, motor drive watchdog systems, and IoT edge node power sequencing requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for STM6321MWY6F 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, delivering silicon solutions for automotive, industrial, and consumer markets since 1987.

The STM6xxx series was engineered specifically for robust, low-power microprocessor supervision in harsh industrial environments - emphasizing guaranteed reset validity down to 1.0 V, wide VCC operating range, and integrated watchdog functionality in minimal footprint.

FAQ

What is the function of the WDI pin on STM6321MWY6F?

The WDI (Watchdog Input) pin monitors MCU health by requiring periodic signal edges; if static for ≥1.6 s, it triggers reset. It clears on any rising or falling edge (≥50 ns), and can be disabled by leaving it floating or connecting to a tristate driver. No external pull-up/down is needed due to internal biasing.

Can STM6321MWY6F be used with a 5 V microcontroller reset input?

Yes - its RST output is active-low open-drain and rated for up to 6 V pull-up, making it compatible with 5 V reset inputs. Use a 10 kΩ pull-up to 5 V; output low voltage stays ≤0.4 V at 1.2 mA sink, ensuring solid logic-low assertion across voltage domains.

Does STM6321MWY6F require external components for basic operation?

Only two external components are mandatory: a 10 kΩ pull-up resistor on RST (for open-drain operation) and a momentary switch (or logic driver) on MR if manual reset is used. No capacitors, resistors, or diodes are needed for VCC monitoring, watchdog, or power-on reset functionality.

How does STM6321MWY6F ensure reset validity during power-down?

It guarantees RST assertion remains valid down to VCC = 1.0 V across –40 to +85 °C, enabling safe MCU shutdown before supply collapse. Unlike push-pull supervisors, its open-drain RST avoids contention during VCC ramp-down, and internal circuitry maintains comparator reference stability well below nominal rail.