Monolithic Power Systems Inc. EVQ4321-D-00A

Overview

EVQ4321-D-00A from Monolithic Power Systems is a fully assembled and tested evaluation board for the MPQ4321GDE-AEC1 - a 3.3V–36V input, 1A synchronous step-down DC/DC converter in QFN-12 (2mm×3mm) with AEC-Q100 Grade 1 qualification, 2.2MHz fixed switching frequency, 1μA shutdown quiescent current, and integrated high-side/low-side MOSFETs. It demonstrates automotive-grade buck conversion in cold-crank, load-dump, and CISPR25 Class 5 EMI-compliant applications.

For engineers reviewing the EVQ4321-D-00A datasheet, EVQ4321-D-00A pinout, EVQ4321-D-00A application, or EVQ4321-D-00A equivalent, this board enables rapid validation of MPQ4321's efficiency (94.4% peak), power-good signaling, frequency programmability (350kHz–2.5MHz), low-dropout mode, and thermal performance under real automotive input transients including 42V load dump and 3.3V cold crank.

Technical Context

The EVQ4321-D-00A implements the MPQ4321's peak-current-mode control architecture with internal 100mΩ HS-FET and 70mΩ LS-FET, supporting adjustable output voltage via external resistor divider (e.g., 5V with R5=100kΩ, R6=19.1kΩ) and programmable switching frequency via FREQ-to-GND resistor (10kΩ–100kΩ). It integrates PG open-drain status signaling with ±5.5% window and thermal shutdown protection.

Board-level design includes dual-stage input EMI filtering (FB1 magnetic bead + CIN1–CIN5 ceramic/polymer capacitors), optimized power loop layout with 2oz copper layers, and dedicated test points (VEMI, VOUT, PG, EN, SW) for oscilloscope probing. The 8.3cm×8.3cm×0.58cm PCB supports direct connection to 6V–36V supplies and 0A–1A electronic loads without external biasing.

Key Specifications

Availability

EVQ4321-D-00A is available at Aetrix Electronics and suitable for automotive ADAS camera modules, infotainment head units, body control modules, and industrial battery-powered telemetry requiring stable component supply and AEC-Q100-qualified reference validation.

Supply support for EVQ4321-D-00A 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 converters, motor drivers, and LED drivers for automotive, industrial, and consumer markets.

The MPQ4321 product line targets automotive power conversion where AEC-Q100 reliability, wide VIN range, low IQ, and EMI robustness are mandatory - specifically engineered for engine bay, dashboard, and ADAS subsystems operating under harsh voltage transients.

FAQ

What input voltage range is supported on the EVQ4321-D-00A board?

The board accepts 6V to 36V DC input, matching the MPQ4321's operational range. It withstands 42V load-dump transients per ISO 7637-2 Pulse 5a, verified with no component stress or regulation loss. Input terminals (VEMI/GND) include EMI filtering optimized for automotive harness noise suppression.

How do I configure the output voltage to 3.3V instead of the default 5V?

Replace R6 (19.1kΩ) with a 31.6kΩ 1% resistor while retaining R5 = 100kΩ, per Equation (1): V_OUT = 0.8V × (1 + R5/R6). The feedback network uses 0603 film resistors with tight tolerance; no PCB modification is required beyond resistor replacement and re-soldering at U1's FB pin.

Does the board support frequency programming, and how is it implemented?

Yes - connect an external resistor between FREQ and GND. Values from 10kΩ to 100kΩ set f_SW from 2.2MHz down to 350kHz. The board includes test point access to FREQ, enabling real-time adjustment without soldering. Frequency foldback during startup prevents inductor current runaway.

Can the EVQ4321-D-00A be used to validate cold-crank performance?

Yes - the board demonstrates low-dropout operation down to 3.3V input at full 1A load, maintaining regulated 5V output with <100mV droop. Thermal imaging shows case temperature rise remains ≤35°C during sustained 3.3V–6V transitions, confirming suitability for engine-start scenarios.

Is the power-good (PG) signal accessible and what are its thresholds?

PG is routed to a dedicated 1mm golden pin and asserts high when V_OUT is within 94.5%–105.5% of nominal (e.g., 4.725V–5.275V for 5V). It is open-drain with 10kΩ pull-up to V_OUT; timing tests show PG assertion within 100μs of valid regulation and deassertion within 200μs of fault.

What components are included for EMI compliance verification?

The board integrates a 1A magnetic bead (FB1), multi-stage ceramic input capacitors (CIN1–CIN5 totaling 35.7μF), and optimized ground/power plane separation - all validated against CISPR25 Class 5 limits for both conducted (150kHz–108MHz) and radiated (150kHz–1GHz) emissions without external filters or shielding.