Monolithic Power Systems Inc. MPQ6411GS-33-Z

Overview

MPQ6411GS-33-Z from Monolithic Power Systems is a windowed watchdog timer IC designed for automotive and industrial microcontroller supervision. It delivers AEC-Q100 Grade 1 qualification, operates from a 3.3V supply, provides programmable short/long window modes via MODE pin, generates a low-active open-drain reset signal (WDO), and features power-on reset with 2.9–3.1V threshold. It is used in engine control units to prevent MCU lockup during voltage transients or software faults.

For engineers reviewing the MPQ6411GS-33-Z datasheet, MPQ6411GS-33-Z pinout, MPQ6411GS-33-Z application, or MPQ6411GS-33-Z equivalent, this page details its window timing behavior, VCC=3.3V operation, SOIC-8 package layout, WDO open-drain drive requirements, and AEC-Q100 compliance for safety-critical embedded systems.

Technical Context

The MPQ6411GS-33-Z implements a dual-state windowed watchdog architecture with MODE-selectable timing windows: short mode (t2=15 cycles, t3=10 cycles) and long mode (t4=1500 cycles, t5=1000 cycles), all referenced to an internal 880µs base period set by a 51kΩ TIMER resistor. Its state machine transitions between sync monitoring, window open/close, and reset pulse generation based on WDI_OK edge timing relative to MODE level.

It integrates power-on reset (POR) with hysteresis (VPOR-HIGH = 2.9–3.1V, VPOR-LOW = 2.8–3.0V), watchdog disable (/WD_DIS) with weak internal pull-up, and WDO output configured as open-drain MOSFET-requiring external pull-up (e.g., 100kΩ) to VCC. All logic thresholds are scaled for 3.3V operation: WDI high ≥2.1V, MODE low ≤0.6V.

Key Specifications

Pinout & Package

MPQ6411GS-33-Z is housed in an industry-standard SOIC-8 package (JEDEC MS-012 AA), with 1.27mm pitch, 3.9mm × 4.9mm body, and gull-wing leads. Pin 1 marked by notch or dot; pin 5 is NC (no connection) and must remain unconnected.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6373ETA+ and TLE8888-2, MPQ6411GS-33-Z delivers optimal balance of AEC-Q100 compliance, 3.3V-native operation, MODE-selectable timing windows, and SOIC-8 footprint - making it the preferred choice for new automotive and industrial MCU supervision designs requiring flexibility and minimal board area.

Availability

MPQ6411GS-33-Z is available at Aetrix Electronics and suitable for automotive engine control units, ADAS camera modules, and industrial PLC I/O modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MPQ6411GS-33-Z 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

Monolithic Power Systems (MPS) is a fabless semiconductor company specializing in high-performance analog and power ICs, with design centers in the US, China, and Taiwan, and global manufacturing partnerships.

The MPQ6411 belongs to MPS's automotive-grade watchdog timer product line, engineered specifically for functional safety-critical MCU supervision in AEC-Q100-compliant systems - emphasizing timing precision, supply robustness, and seamless integration into existing 3.3V microcontroller platforms.

FAQ

What is the recommended external pull-up resistor value for the WDO pin?

The WDO pin is an open-drain output requiring an external pull-up resistor to VCC. A 100kΩ resistor is explicitly recommended in the datasheet for MPQ6411GS-33-Z to ensure proper rise time and noise immunity while minimizing current draw during reset assertion. Lower values (e.g., 10kΩ) may improve speed but increase static power; higher values risk slow edges in noisy environments.

How does the TIMER pin resistor value affect watchdog timing?

The TIMER pin sets the base period (T) using an external resistor: T ≈ (15.75 × RTIMER + 73.5) µs. For RTIMER = 51kΩ, T ≈ 880µs. All window durations scale linearly with T - e.g., short-mode t2 = 15 × T ≈ 13.2ms. Selecting RTIMER adjusts absolute timing resolution without changing window ratios or MODE behavior.

Can the MPQ6411GS-33-Z operate with a 5V supply?

No. The MPQ6411GS-33-Z is specifically rated for 3.3V ±10% operation (2.97–3.63V). Using 5V exceeds its absolute maximum rating of +6V on VCC but violates recommended operating conditions and risks incorrect logic thresholds, POR behavior, and long-term reliability. For 5V systems, use MPQ6411GS or MPQ6411GS-AEC1 instead.

What happens if the /WD_DIS pin is left unconnected?

The /WD_DIS pin has a weak internal pull-up, so leaving it unconnected defaults the watchdog to enabled state. This is safe for normal operation but means the watchdog cannot be disabled without adding external circuitry. For debug or bootloader scenarios requiring watchdog disable, explicitly tie /WD_DIS to GND via a jumper or GPIO-controlled FET.

Is the NC (pin 5) electrically isolated or internally bonded?

Pin 5 is designated NC (No Connection) in the datasheet and functional block diagram - it is not electrically connected to any internal circuitry and must remain unconnected on the PCB. Bonding or routing to any net may cause unpredictable behavior or damage; the pin is physically present for mechanical symmetry but electrically inert.

How does the WDI_OK pulse width tolerance impact system design?

The WDI_OK pulse width must be between 10µs and 5ms (low duration) to be recognized as valid. MCU firmware must guarantee minimum low time ≥10µs to avoid missed synchronization, and maximum low time ≤5ms to prevent WDI error detection and unintended reset. This constrains GPIO toggle timing but ensures robust glitch rejection.

Does the MPQ6411GS-33-Z support watchdog window reconfiguration during runtime?

Yes. Changing the MODE pin logic level (high/low) dynamically switches between short and long window modes without reset or power cycle. This allows firmware to adapt supervision granularity - e.g., use short windows during boot sequence and switch to long windows after OS initialization - enhancing both safety and operational resilience.