STMicroelectronics STWD100NWWY3F

Overview

STWD100NWWY3F from STMicroelectronics is a single-channel, automotive-qualified watchdog timer IC with fixed timeout periods (3.4 ms, 6.3 ms, 102 ms, and 1.6 s), 13 µA typical supply current, open-drain or push-pull WDO output, and chip enable (EN) input - used to detect MCU lockup in industrial control and automotive power management systems.

For engineers reviewing the STWD100NWWY3F datasheet, STWD100NWWY3F pinout, STWD100NWWY3F application, or STWD100NWWY3F equivalent, key selection criteria include timeout flexibility, EN-controlled enable/disable behavior, WDO output configuration (open-drain vs. push-pull), –40 to 125 °C operating range, and SOT23-5 package compatibility with space-constrained PCB layouts.

Technical Context

The STWD100NWWY3F implements a self-contained watchdog timer with independent reset timing logic, no external components required. Its internal counter resets on valid WDI transitions (low-to-high only), EN pulses ≥1 µs, or WDO toggling - and asserts active-low WDO after timeout unless cleared.

It supports dual output modes: open-drain (requiring external pull-up) or push-pull (with VOH ≥0.8 VCC at ISOURCE = 500 µA). The EN pin features an internal 32–100 kΩ pull-down, enabling default operation when left floating, and provides synchronous reset capability with glitch immunity (<100 ns).

Key Specifications

Pinout & Package

STWD100NWWY3F is housed in a RoHS-compliant, lead-free SOT23-5 package (3.0 × 2.8 × 1.3 mm), optimized for automated placement and reflow soldering in high-reliability automotive and industrial assemblies.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar watchdog timer applications.

Compared with MAX6375US29D3+ and TLC372IPW, STWD100NWWY3F delivers factory-trimmed timeout accuracy, integrated EN control, automotive qualification, and lower design risk - making it optimal for safety-aware, production-critical systems requiring zero-tolerance fault coverage.

Availability

STWD100NWWY3F is available at Aetrix Electronics and suitable for industrial PLC control, automotive body control modules, and medical infusion pumps requiring stable component supply across extended product lifecycles.

Supply support for STWD100NWWY3F 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 automotive, industrial, and consumer markets.

The STWD100 belongs to ST's automotive-grade watchdog timer product line, engineered specifically for fault-tolerant supervision of safety-critical microcontrollers in harsh thermal and EMI environments.

FAQ

What is the function of the EN pin on STWD100NWWY3F?

The EN (Enable) pin controls watchdog functionality: pulling EN high for ≥1 µs disables or resets the timer, while its internal 32–100 kΩ pull-down resistor ensures default-enabled operation when left floating. This allows safe deactivation during firmware updates without external circuitry.

Can STWD100NWWY3F drive a microcontroller reset pin directly?

Yes - when configured in push-pull mode (verified by part marking 'W' in position 4 of top-side code 'WNW'), STWD100NWWY3F drives WDO actively high/low and interfaces directly to bidirectional reset pins. In open-drain mode, a 10 kΩ external pull-up to ≤6 V is required.

How does STWD100NWWY3F handle power-up sequencing?

At power-up, the internal timer starts counting only after VCC exceeds VSTART (1.9–2.7 V); WDO remains high until timeout occurs. This prevents false resets during slow-ramp or brown-out conditions common in automotive 12 V systems with DC-DC converters.

Is STWD100NWWY3F qualified for automotive applications?

Yes - the 'Y' in the order code STWD100NWWY3F indicates AEC-Q100 qualification, and the device is rated for –40 to 125 °C operation with HBM 2000 V/CDM 1000 V ESD robustness, meeting requirements for body electronics and powertrain auxiliary modules.