STMicroelectronics STWD100YNXWY3F

Overview

STWD100YNXWY3F from STMicroelectronics is an automotive-qualified watchdog timer IC that monitors microcontroller operation by detecting software hangs or hardware faults via its WDI input and asserting a reset signal on the active-low WDO output. It offers four factory-set timeout periods (3.4 ms, 6.3 ms, 102 ms, 1.6 s), consumes only 13 µA typical supply current, operates from –40 to 125 °C, and supports both open-drain and push-pull WDO configurations for flexible system integration in safety-critical automotive ECUs.

For engineers reviewing the STWD100YNXWY3F datasheet, STWD100YNXWY3F pinout, STWD100YNXWY3F application, or STWD100YNXWY3F equivalent, key selection considerations include timeout period matching, EN pin enable/disable behavior, WDO output type compatibility with host reset circuitry, and AEC-Q100 qualification status for automotive deployment.

Technical Context

The STWD100YNXWY3F implements a self-contained, single-chip watchdog timer with independent internal timing logic-no external components required. Its timeout period is fixed per variant (this part uses the 1.6 s setting), and reset assertion is triggered only when WDI is not toggled within t_WD, or when EN is pulsed high for ≥1 µs.

It features dual-mode WDO output (selectable open-drain or push-pull), an internally pulled-down EN pin enabling watchdog functionality when left floating, and robust noise immunity with 100 ns glitch rejection on both WDI and EN inputs-critical for noisy automotive environments where false resets must be avoided.

Key Specifications

Pinout & Package

STWD100YNXWY3F is packaged in SOT23-5, a surface-mount 5-pin package measuring 2.9 mm × 2.8 mm × 1.3 mm (max), suitable for space-constrained automotive PCB layouts and compatible with standard reflow soldering profiles (peak 260 °C).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3823-33DBVR and MAX6373XS29D3+T, STWD100YNXWY3F uniquely combines AEC-Q100 qualification, factory-trimmed 1.6 s timeout accuracy, EN pin controllability, and dual-mode WDO-making it the only drop-in solution for ASIL-B automotive subsystems requiring deterministic, low-risk reset supervision.

Availability

STWD100YNXWY3F is available at Aetrix Electronics and suitable for automotive electronic control units, ADAS camera modules, and electric power steering controllers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for STWD100YNXWY3F 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, digital, and mixed-signal ICs for automotive, industrial, and consumer markets.

The STWD100 product line delivers highly reliable, low-power watchdog timers specifically engineered for automotive safety-critical applications-including engine control, chassis systems, and driver assistance-where deterministic reset behavior and AEC-Q100 compliance are mandatory.

FAQ

What is the exact watchdog timeout period for STWD100YNXWY3F?

The STWD100YNXWY3F is factory-configured for a nominal watchdog timeout period of 1.6 seconds, with a guaranteed range of 1.12 s to 2.24 s over full temperature and voltage conditions. This value is fixed per device variant and cannot be adjusted externally-it is selected at manufacture based on the order code suffix "Y" indicating the 1.6 s option.

Does STWD100YNXWY3F support both open-drain and push-pull WDO outputs?

Yes-STWD100YNXWY3F supports both output types, but the configuration is fixed at manufacture and determined by the specific order code. The "YNXWY3F" suffix corresponds to the push-pull WDO variant. Open-drain versions use different suffixes (e.g., "NWWY3F"). Datasheet Table 4 confirms VOH and VOL specifications valid only for push-pull operation.

How is the EN pin used to disable the watchdog function?

The EN pin has an internal 32–100 kΩ pull-down resistor. To disable the watchdog, drive EN low (≤0.3×VCC); to enable it, leave EN floating or drive it high (≥0.7×VCC). A ≥1 µs high pulse on EN also resets the internal timer-this feature enables synchronized initialization without toggling WDI.

Is STWD100YNXWY3F qualified for automotive use beyond temperature range?

Yes-STWD100YNXWY3F is fully qualified per AEC-Q100 Grade 1 (–40 to 125 °C) and undergoes additional screening per AEC-Q001/Q002. Its construction, test flow, and reliability data-including HBM ESD (2000 V) and CDM ESD (1000 V)-are documented in ST's official qualification reports and meet requirements for safety-critical automotive ECUs.