Monolithic Power Systems Inc. EVQ4321-D-01A

Overview

EVQ4321-D-01A from Monolithic Power Systems is a fully assembled and tested evaluation board for the MPQ4321 AEC-Q100-qualified synchronous step-down converter, supporting 3.3V–36V input, 42V load dump tolerance, 1A output at 5V, and 2.2MHz switching frequency in a QFN-12 (2mm×3mm) package. It demonstrates cold-crank operation, frequency foldback, power-good signaling, and ultra-low 1μA shutdown quiescent current for automotive power rail validation.

For engineers reviewing the EVQ4321-D-01A datasheet, EVQ4321-D-01A pinout, EVQ4321-D-01A application, or EVQ4321-D-01A equivalent, this board enables rapid characterization of MPQ4321's efficiency across 0–1A loads, thermal performance under no airflow, CISPR 25 Class 5 EMI compliance, and transient response to load dump (12V→42V) and cold-crank (12V→3.3V) events.

Technical Context

The EVQ4321-D-01A implements the MPQ4321 IC in a fixed 5V/1A configuration with selectable 415kHz or 2.2MHz fSW via external resistor on FREQ pin, and supports adjustable VOUT (1V–5V) using FB divider resistors R5/R6. It integrates internal HS/LS MOSFETs, peak current mode control, and thermal shutdown protection.

Board-level features include dual-output capability (5V and 3.3V jumpers), EMI filtering (FB1 magnetic bead + CIN1–CIN5), low-DCR 5.6μH inductor (XAL5050-562MEC), and wettable-flank QFN-12 mounting for automated optical inspection. Input voltage ramping, EN-controlled sequencing, and PG monitoring are accessible via test points.

Key Specifications

Availability

EVQ4321-D-01A is available at Aetrix Electronics and suitable for automotive ECU development, ADAS power subsystem validation, and infotainment system design requiring stable component supply, AEC-Q100-compliant reference hardware, and fast-turn prototyping support.

Supply support for EVQ4321-D-01A 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 computing markets.

The MPQ4321 product line targets automotive power conversion applications demanding high reliability, wide VIN range, and robust fault handling-specifically engineered for front-end DC/DC stages in telematics, camera modules, and gateway ECUs operating in harsh electrical environments.

FAQ

What input voltage range does the EVQ4321-D-01A support?

The board accepts 3.3V to 36V DC input, with demonstrated 42V load dump tolerance per AEC-Q100 stress testing. It operates down to 3.3V during cold-crank conditions while maintaining regulated 5V output, verified by thermal imaging and output ripple measurements at 1A load.

How do I change the output voltage from 5V to 3.3V?

Remove the 0Ω resistor R4 and install a 31.6kΩ resistor (R6) in parallel with R8 (47.5kΩ) to set the feedback divider ratio. The board includes pre-populated pads and silkscreen labels for both 5V and 3.3V configurations; refer to Figure 1 and Table on page 4 of the EVB guide for exact resistor values.

Does the EVQ4321-D-01A support frequency adjustment?

Yes-connect an external resistor between FREQ and GND to set switching frequency from 350kHz to 2.5MHz. The board ships with R3 (86.6kΩ) installed for 415kHz and R9 (18.2kΩ) + R8 (47.5kΩ) network for 2.2MHz; resistor values and corresponding fSW are tabulated on page 4 of the reference document.

Is the power-good (PG) signal accessible for system monitoring?

Yes-the open-drain PG signal is routed to a 1mm golden test pin labeled "PG" and is active when VOUT is within ±5.5% of nominal (e.g., 4.725V–5.275V at 5V). Its timing behavior-including assertion delay (~100μs) and glitch immunity-is characterized in startup/shutdown waveforms on pages 12–14.

Can the EVQ4321-D-01A be used for EMI pre-compliance testing?

Yes-it has been fully validated to CISPR 25 Class 5 limits for conducted (150kHz–108MHz) and radiated (150kHz–1GHz) emissions in both horizontal and vertical polarization, with measurement data and noise floor margins provided on pages 10–11. No external filters or shielding were added during testing.

What is the maximum continuous output current at elevated temperature?

The board delivers 1A continuously at TA = 25°C with ≤30.4°C case temperature rise and no forced airflow. Derating is not required up to 85°C ambient when mounted on a 2oz copper PCB with ≥4 cm² thermal pad area, as confirmed by thermal imaging in Figure 8 on page 8.