STMicroelectronics STM812LW16F

Overview

STM812LW16F from STMicroelectronics is an industrial-grade active-high reset supervisor IC with manual reset input, designed for reliable power-on and brown-out detection in microcontroller-based systems. It monitors 4.50–4.75 V supply rails, delivers a guaranteed 140 ms minimum reset pulse width, asserts valid RST down to VCC = 1.0 V, and draws only 6 µA typical supply current - enabling robust system initialization in embedded control and industrial instrumentation.

For engineers reviewing the STM812LW16F datasheet, STM812LW16F pinout, STM812LW16F application, or STM812LW16F equivalent, key selection criteria include its SOT143-4 package compatibility, push-button MR input with internal 20 kΩ pull-up, guaranteed reset assertion during VCC transients ≤100 mV/20 µs, and operation across –40 °C to +85 °C.

Technical Context

The STM812LW16F implements a precision voltage comparator with 4.63 V nominal reset threshold (±25 mV over –40 °C to +85 °C), integrated debounce logic for the MR input, and a temperature-stable trec timer generating ≥140 ms reset pulses. Its push-pull RST output sources/sinks up to 20 mA and remains valid down to VCC = 1.0 V.

Unlike STM809/810, it features both active-high RST and manual reset (MR) inputs in a 4-terminal SOT143-4 package. The MR input accepts TTL/CMOS levels, includes internal 20 kΩ pull-up, and provides 100 ns glitch immunity - eliminating need for external debounce circuitry in most applications.

Key Specifications

Pinout & Package

SOT143-4 (W1) package: 4-pin, surface-mount, lead-free, 2.8 mm × 2.1 mm footprint with 1.92 mm pin pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809LTA+T and TPS3808G15DBVR, the STM812LW16F uniquely integrates MR functionality and active-high RST in a compact 4-pin package - reducing BOM count and PCB area while enabling field-service reset and direct MCU interface without level-shifting.

Availability

STM812LW16F is available at Aetrix Electronics and suitable for industrial PLC controllers, smart energy meters, medical handheld diagnostics, and factory automation I/O modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for STM812LW16F 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, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The STM8xx series was developed specifically for cost-sensitive, space-constrained embedded systems requiring high-reliability power supervision with minimal external components and guaranteed reset timing.

FAQ

What is the function of the MR pin on STM812LW16F?

The MR (Manual Reset) pin is an active-low input with an internal 20 kΩ pull-up resistor. When pulled to ground via a push-button or logic signal, it immediately asserts the RST output high for at least 140 ms after release. It requires no external components and provides 100 ns glitch immunity, making it ideal for field-service reset or emergency shutdown circuits.

Can STM812LW16F monitor a 3.3 V supply?

No - the 'L' suffix denotes a 4.50–4.75 V reset threshold optimized for 4.5 V or 5 V systems. For 3.3 V monitoring, select STM812TW16F (3.00–3.15 V threshold) or STM812SW16F (2.85–3.00 V). Using STM812LW16F on 3.3 V will result in continuous reset assertion since VCC remains below VRST.

Is a pull-up resistor required on the RST output?

No - the RST output is push-pull and actively drives both high and low states. A 100 kΩ pull-up to VCC is recommended only if RST must remain valid when VCC falls below 1.0 V; otherwise, the internal driver fully controls the signal without external biasing.

How does STM812LW16F handle short VCC transients?

It suppresses reset pulses for negative-going VCC transients ≤100 mV in amplitude and ≤20 µs in duration, per Figure 12 in the datasheet. This immunity is achieved through internal comparator hysteresis and timing filtering, eliminating false resets caused by switching noise or load dumps without requiring additional external filtering capacitors.