STMicroelectronics STM1811LWX7F

Overview

STM1811LWX7F from STMicroelectronics is an open-drain, active-low voltage supervisor IC designed for precise 3.3 V/3.0 V supply monitoring in microcontroller-based systems. It features a factory-trimmed 2.88 V reset threshold (±2.5% over –40 °C to +105 °C), 100 ms minimum reset pulse width, 4 µA typical supply current, and guaranteed operation down to VCC = 1.0 V. It is used in portable embedded systems requiring reliable power-on reset and brownout protection.

For engineers reviewing the STM1811LWX7F datasheet, STM1811LWX7F pinout, STM1811LWX7F application, or STM1811LWX7F equivalent, this device is selected for low-power, space-constrained designs needing open-drain reset assertion with internal 5.5 kΩ pull-up, bidirectional MCU interface support, and immunity to fast VCC transients.

Technical Context

The STM1811LWX7F implements a precision bandgap reference and comparator to monitor VCC against a fixed 2.88 V threshold. Its open-drain RST output includes an integrated 5.5 kΩ pull-up resistor to VCC, eliminating external components when interfacing with bidirectional MCU reset pins.

Reset assertion is triggered when VCC falls below 2.88 V and remains active for ≥100 ms after VCC rises above threshold. The device ignores negative-going VCC transients ≤20 µs at 100 mV overdrive and operates across –40 °C to +105 °C with no external timing components required.

Key Specifications

Pinout & Package

STM1811LWX7F is housed in a 3-pin SOT23-3 (WX) package - a surface-mount, ultra-compact outline measuring 2.9 mm × 1.3 mm × 1.0 mm, 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 MAX809LTR and TPS3808G125DBVR, STM1811LWX7F delivers optimal balance of low power (4 µA), integrated pull-up (reducing component count), and tight threshold accuracy (±2.5%) in the smallest possible SOT23-3 footprint - making it ideal for cost- and space-sensitive 3.3 V embedded systems.

Availability

STM1811LWX7F is available at Aetrix Electronics and suitable for industrial PLC I/O modules, portable medical sensor nodes, automotive body control modules, and smart home Zigbee routers requiring stable component supply across extended product lifecycles.

Supply support for STM1811LWX7F 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 power management, microcontrollers, sensors, and analog ICs for industrial, automotive, and consumer markets.

STM181x is ST's low-power voltage supervisor product line, engineered specifically for reliable reset generation in battery-powered and thermally demanding embedded systems with minimal external components.

FAQ

What is the exact reset threshold voltage of STM1811LWX7F and how stable is it over temperature?

The STM1811LWX7F has a factory-trimmed nominal reset threshold of 2.88 V, with ±2.5% accuracy guaranteed over the full operating temperature range of –40 °C to +105 °C. This stability is achieved via laser-trimmed on-chip resistors and a precision bandgap reference, eliminating drift-related reset errors in thermal cycling environments.

Does STM1811LWX7F require an external pull-up resistor on the RST pin?

No. STM1811LWX7F integrates a 5.5 kΩ pull-up resistor from RST to VCC, enabling direct connection to bidirectional MCU reset pins without external components. This feature reduces BOM count and PCB area while maintaining compatibility with standard open-drain reset interfaces.

Can STM1811LWX7F be used with a 5 V supply rail?

Yes - STM1811LWX7F operates across VCC = 1.0 V to 5.5 V and is rated for absolute maximum VCC = 7.0 V. However, its 2.88 V reset threshold is optimized for 3.3 V/3.0 V systems; for 5 V rails, ST recommends STM1810LWX7F (4.37 V threshold) or STM1815LWX7F (4.62 V threshold) instead.

How does STM1811LWX7F handle short VCC transients, and what is its immunity specification?

STM1811LWX7F rejects negative-going VCC transients ≤20 µs in duration when the overdrive (VTH – VCC) is ≤100 mV, per Figure 19 in the datasheet. This immunity is achieved through internal filtering and comparator hysteresis, preventing false resets caused by switching regulator noise or ESD-induced supply dips.