STMicroelectronics STM6321RWY6F

Overview

STM6321RWY6F from STMicroelectronics is a 5-pin precision voltage supervisor IC with integrated watchdog timer and manual reset input, designed for microprocessor system monitoring. It monitors VCC at 3.3 V (±2.5%), asserts active-low open-drain RST output on fault, provides 1.4 ms reset pulse width (typ.), 1.6 s watchdog timeout (typ.), and operates down to VCC = 1.0 V - used in industrial embedded controllers requiring reliable power-on reset and firmware recovery.

For engineers reviewing the STM6321RWY6F datasheet, STM6321RWY6F pinout, STM6321RWY6F application, or STM6321RWY6F equivalent, key selection criteria include its open-drain RST output compatibility with multi-rail systems, guaranteed reset assertion below 1.0 V, low 3 µA supply current, and SOT23-5 footprint for space-constrained PCBs.

Technical Context

The STM6321RWY6F implements a precision bandgap reference and comparator to monitor VCC against a fixed 3.3 V threshold (±2.5% over –40 to +85 °C). Its reset logic asserts RST low whenever VCC drops below VRST, MR is pulled low, or WDI fails to toggle within 1.6 s - with trec = 1.4 ms after recovery.

It features an internal 52 kΩ pull-up on MR, supports external push-button reset without debounce, and allows watchdog disable via floating WDI. The open-drain RST output requires an external pull-up (e.g., 10 kΩ) and sinks ≥20 mA, enabling level-shifting across supply domains up to 6 V.

Key Specifications

Pinout & Package

STM6321RWY6F is housed in a RoHS-compliant SOT23-5 package (2.9 × 1.6 × 1.1 mm), optimized for high-density PCB layouts and reflow-compatible assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar voltage supervisor with watchdog applications.

Compared with STM6321RWY6F, STM6322RWY6F trades open-drain flexibility for simpler push-pull drive, while TPS3808G33DBVR omits MR and uses fixed 200 ms reset timing - making STM6321RWY6F uniquely suited for designs needing manual reset, multi-rail compatibility, and precise 1.4 ms reset assertion.

Availability

STM6321RWY6F is available at Aetrix Electronics and suitable for industrial PLC controllers, medical diagnostic devices, smart energy meters, and automotive body control modules requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for STM6321RWY6F 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, specializing in microcontrollers, power management, analog, and sensor solutions for industrial, automotive, and consumer markets.

STM632x belongs to ST's precision voltage supervisor product line, engineered specifically for robust microprocessor reset and watchdog functionality in harsh industrial and medical environments.

FAQ

What is the function of the WDI pin on STM6321RWY6F?

The WDI (Watchdog Input) pin monitors MCU health by requiring a rising or falling edge at least once every 1.6 seconds. If no transition occurs, the device asserts RST. WDI can be left unconnected to disable the watchdog function, as the internal timer remains inactive without signal activity.

Can STM6321RWY6F be used with a 1.8 V microcontroller reset input?

Yes - its open-drain RST output is compatible with 1.8 V logic when pulled up to 1.8 V. The output sinks current when asserted and presents high-impedance otherwise, allowing direct interface without level shifters. A 10 kΩ pull-up resistor to 1.8 V is recommended for reliable logic levels.

Does STM6321RWY6F require external components for basic operation?

Only two external components are required for standard use: a 10 kΩ pull-up resistor on the RST pin and a momentary switch (or logic driver) on the MR pin. No external capacitors or resistors are needed for VCC monitoring, watchdog, or reset timing - all functions are internally calibrated.

How does STM6321RWY6F ensure reset validity during deep brown-out?

It guarantees RST assertion down to VCC = 1.0 V across –40 to +85 °C, verified by internal circuit design and characterization. This ensures the reset signal remains valid and drives the host MCU into reset even when supply voltage collapses below typical logic thresholds, preventing undefined MCU states.