Monolithic Power Systems Inc. MPQ4321GDE-5-AEC1-Z

Overview

MPQ4321GDE-5-AEC1-Z from Monolithic Power Systems is an AEC-Q100 Grade-1 qualified, synchronous step-down DC/DC converter delivering 1A continuous output current with 3.3V–36V input range and 42V load dump tolerance. It integrates 70mΩ high-side and 50mΩ low-side MOSFETs, supports adjustable or fixed 5V output (this variant is fixed 5V), and operates from –40°C to +150°C junction temperature-designed for automotive infotainment power rails.

For engineers reviewing the MPQ4321GDE-5-AEC1-Z datasheet, MPQ4321GDE-5-AEC1-Z pinout, MPQ4321GDE-5-AEC1-Z application, or MPQ4321GDE-5-AEC1-Z equivalent, key selection criteria include its 1μA shutdown current, 415kHz default switching frequency (configurable up to 2.5MHz), CISPR25 Class 5 EMI compliance, wettable-flank QFN-12 (2mm×3mm) package, and cold-crank support down to 3.1V input.

Technical Context

The MPQ4321GDE-5-AEC1-Z employs peak current mode control with frequency foldback during startup to prevent inductor current runaway. Its integrated power stage uses a MeshConnect™ flip-chip QFN package with symmetric VIN pinout and spread-spectrum modulation to meet stringent automotive EMC requirements per CISPR25 Class 5.

It features a dedicated open-drain power-good (PG) output with ±5.5% window (94.5%–105.5% of nominal VOUT), hiccup-mode over-current protection, thermal shutdown at 175°C (20°C hysteresis), and low-dropout operation enabling stable 5V output even during automotive cold-crank events down to 3.1V input.

Key Specifications

Pinout & Package

MPQ4321GDE-5-AEC1-Z is housed in a wettable-flank QFN-12 package measuring 2mm × 3mm, optimized for automated optical inspection (AOI) and high-reliability automotive reflow profiles.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous step-down converter applications.

Compared with MPQ4321GDE-5-AEC1-Z, the adjustable MPQ4321GDE-AEC1-Z offers design reuse across voltage variants, while LM61480QRNXTQ1 lacks certified 42V transient immunity-making the MPQ4321GDE-5-AEC1-Z uniquely suited for cost-sensitive, high-reliability automotive 5V rails.

Availability

MPQ4321GDE-5-AEC1-Z is available at Aetrix Electronics and suitable for automotive infotainment, instrument clusters, ADAS camera modules, and industrial vehicle telematics requiring stable component supply with full AEC-Q100 traceability and automotive-grade lot control.

Supply support for MPQ4321GDE-5-AEC1-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 power management ICs, with over two decades of expertise in DC/DC conversion, motor drivers, and battery management.

The MPQ4321 product line targets automotive power conversion with emphasis on load dump resilience, ultra-low IQ, and EMI robustness-designed specifically for next-generation ECUs where space, thermal, and regulatory constraints dominate.

FAQ

What is the default output voltage of MPQ4321GDE-5-AEC1-Z?

This variant is factory-configured for fixed 5.0V output with ±1.5% accuracy over –40°C to +150°C. The FB pin is internally connected to the output; no external resistors are required, simplifying layout and improving long-term stability versus adjustable versions.

Does MPQ4321GDE-5-AEC1-Z require an external bootstrap capacitor?

Yes-a 0.1µF ceramic capacitor must be placed between BOOT and SW pins. This capacitor sustains the high-side gate driver voltage during duty cycles above ~90%, ensuring reliable switching during low-input conditions like cold crank.

How is the switching frequency set on this device?

Frequency is set by a resistor from the FREQ pin to GND. For MPQ4321GDE-5-AEC1-Z, a typical 86.6kΩ resistor yields 415kHz. Values from 15kΩ to 100kΩ configure frequencies from 2.2MHz down to 350kHz, allowing optimization for efficiency, size, or EMI.

Is the PG (power good) signal active-high or open-drain?

PG is an open-drain output requiring an external pull-up resistor (typically 10kΩ to 5V or VOUT). It asserts high when output voltage is within 94.5%–105.5% of 5V and pulls low outside that window-enabling flexible interfacing with MCU reset or supervisor circuits.

What thermal performance can be expected in the QFN-12 (2mm×3mm) package?

On a standard 4-layer 2oz copper evaluation board, θJA is 60°C/W and θJC is 7.3°C/W. At 1A load and 12V input, case temperature rise is typically <12°C-enabling operation without heatsinking in most automotive ambient conditions up to 85°C.

Can MPQ4321GDE-5-AEC1-Z operate below 3.3V input?

No-the absolute minimum operating input is 3.1V after startup, but the undervoltage lockout rising threshold is 3.65V. It will not start below ~3.9V, and sustained operation below 3.3V is outside specification. Cold-crank support applies only after initial startup.

Does this part support forced PWM or only auto-frequency scaling?

It operates exclusively in Advanced Asynchronous Mode (AAM), which automatically reduces switching frequency under light loads to maintain high efficiency. There is no forced-PWM mode; frequency foldback and burst-mode behavior are inherent to its control architecture.