STMicroelectronics STM809SWX6F

Overview

STM809SWX6F from STMicroelectronics is a precision 2.85 V to 3.00 V supply voltage supervisor IC in SOT23-3 package, featuring active-low push-pull RST output, 140 ms minimum reset pulse width, 6 µA typical supply current, and guaranteed RST assertion down to VCC = 1.0 V. It monitors 3.3 V systems in industrial embedded controllers where reliable power-on reset and brownout detection are critical.

For engineers reviewing the STM809SWX6F datasheet, STM809SWX6F pinout, STM809SWX6F application, or STM809SWX6F equivalent, key selection criteria include reset threshold accuracy (±2.5% over –40 °C to 85 °C), low-power operation at 1.2 V–5.5 V supply range, SOT23-3 footprint compatibility, and immunity to sub-100 ns MR glitches.

Technical Context

The STM809SWX6F implements a precision bandgap-based voltage comparator with internal hysteresis and a monostable timer for reset pulse generation. Its reset threshold is fixed at 2.93 V (typ) with ±2.5% tolerance across temperature, and it guarantees valid RST assertion even as VCC drops to 1.0 V - enabling robust reset behavior during deep brownouts.

Unlike STM811/812 variants, it lacks manual reset (MR) input and dual RST outputs, simplifying integration in space-constrained 3-pin applications. The push-pull RST driver sinks and sources current, eliminating external pull-up requirements while maintaining compatibility with TTL/CMOS inputs.

Key Specifications

Pinout & Package

SOT23-3 package: compact 3-pin surface-mount outline (2.8 mm × 2.1 mm × 1.0 mm), lead-free ECOPACK® compliant, optimized for high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809TRD3T and TPS3808G12DBVR, the STM809SWX6F delivers superior brownout resilience (1.0 V VCC operation), simpler integration (no external components), and tighter threshold tolerance (±2.5% vs. ±3.5% typical), making it optimal for cost-sensitive industrial 3.3 V systems requiring guaranteed reset behavior under worst-case supply collapse.

Availability

STM809SWX6F is available at Aetrix Electronics and suitable for industrial PLCs, smart energy meters, POS terminals, and network edge routers requiring stable component supply with long-term lifecycle assurance.

Supply support for STM809SWX6F 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 microcontrollers, power management ICs, sensors, and analog devices for industrial, automotive, and consumer markets.

The STM809 series belongs to ST's precision voltage supervisor product line, engineered specifically for deterministic power-on reset and brownout protection in resource-constrained embedded systems operating from 1.2 V to 5.5 V rails.

FAQ

What is the exact reset threshold voltage for STM809SWX6F?

The STM809SWX6F has a nominal reset threshold of 2.93 V, with a guaranteed range of 2.85 V to 3.00 V across –40 °C to +85 °C ambient temperature. This corresponds to the 'S' grade in ST's ordering scheme and is verified per Table 5 of Doc ID 9873 Rev 5.

Does STM809SWX6F support manual reset functionality?

No, STM809SWX6F does not include a manual reset (MR) input. It is a 3-pin device (VCC, GND, RST) without MR terminal - unlike the 4-pin STM811/812 variants. Manual reset capability requires selecting STM811SW16F or STM812SW16F instead.

Can STM809SWX6F operate reliably below 1.2 V supply?

Yes - STM809SWX6F guarantees RST assertion down to VCC = 1.0 V over the full industrial temperature range, as specified in Section 2.1 and Table 5 of the datasheet. Below 1.0 V, RST becomes high-impedance, but the device remains functional until VCC reaches 1.2 V minimum operating voltage.

Is the RST output push-pull or open-drain?

The RST output is push-pull, capable of both sourcing and sinking current. It drives actively low with ≤0.3 V output at 1.2 mA sink load (per Table 5), eliminating the need for an external pull-up resistor and ensuring clean, fast edges into capacitive MCU reset inputs.