STMicroelectronics STM809MWX6F

Overview

STM809MWX6F from STMicroelectronics is a precision low-power active-low reset supervisor IC for 3.3 V supply monitoring in industrial microcontroller systems. It features a 4.31–4.45 V reset threshold (typ. 4.38 V), 140 ms minimum reset pulse width, 6 µA typical supply current, guaranteed RST assertion down to VCC = 1.0 V, and operates from –40 °C to +85 °C in SOT23-3 package. It is used in embedded power-up sequencing and brown-out protection circuits.

For engineers reviewing the STM809MWX6F datasheet, STM809MWX6F pinout, STM809MWX6F application, or STM809MWX6F equivalent, key selection criteria include reset threshold tolerance, temperature stability (±45 ppm/°C), manual reset absence (STM809 variant), push-pull RST drive capability, and compatibility with 3.3 V MCU supply rails requiring reliable power-on reset assertion.

Technical Context

The STM809MWX6F implements a precision voltage comparator with internal hysteresis and an on-chip timer that generates a minimum 140 ms active-low reset pulse after VCC rises above the threshold. Its reset output remains valid down to VCC = 1.0 V across the full industrial temperature range, ensuring deterministic MCU initialization during marginal supply conditions.

No manual reset input (MR) is present-this distinguishes it from STM811/812 variants. The device uses a single-supply push-pull RST output stage capable of sinking ≥3.2 mA at VRST(min), eliminating external pull-up requirements while maintaining logic-level compatibility with standard CMOS inputs.

Key Specifications

Pinout & Package

SOT23-3 (WX) package: compact 3-pin surface-mount outline with 0.95 mm max height, 2.8 mm × 2.1 mm footprint, and lead-free ECOPACK® compliance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809TRD3T and TPS3808G33DBVR, the STM809MWX6F provides superior brown-out coverage (1.0 V VCC operation), tighter tempco (±45 ppm/°C), and guaranteed push-pull drive strength-making it optimal for industrial 3.3 V systems where reliability under marginal supply conditions is non-negotiable.

Availability

STM809MWX6F is available at Aetrix Electronics and suitable for industrial PLCs, smart meters, medical handhelds, and factory automation sensor nodes requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for STM809MWX6F 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, designing and manufacturing analog, MCU, power, and sensing solutions for industrial, automotive, and consumer markets.

The STM809 series belongs to ST's precision supervisory IC product line, engineered specifically for high-reliability power monitoring in industrial embedded systems where deterministic reset behavior under voltage stress is critical.

FAQ

What is the exact reset threshold voltage for STM809MWX6F?

The STM809MWX6F has a nominal reset threshold of 4.38 V, with a guaranteed range of 4.31 V (min) to 4.45 V (max) over the full –40 °C to +85 °C operating temperature range, as specified in Table 5 of the official STMicroelectronics datasheet (Doc ID 9873 Rev 5).

Does STM809MWX6F support manual reset functionality?

No. STM809MWX6F is the base variant without manual reset (MR) input. Only STM811 and STM812 include the MR pin; the STM809/810 family provides only VCC-monitored reset assertion with no external trigger capability.

Can STM809MWX6F drive a standard CMOS /RESET input directly?

Yes. Its push-pull RST output sinks ≥3.2 mA at VRST(min) and sources sufficient current to meet CMOS high-level input requirements, eliminating the need for an external pull-up resistor in most MCU interface configurations.

Is STM809MWX6F compatible with 3.3 V logic systems?

Yes - it is specifically optimized for 3.3 V supply supervision. Its 4.38 V reset threshold ensures reliable detection of undervoltage conditions on 3.3 V rails, and its RST output is fully compatible with 3.3 V-tolerant MCU reset inputs, including those requiring active-low assertion.