Monolithic Power Systems Inc. EVQ4425B-QB-00A

Overview

EVQ4425B-QB-00A from Monolithic Power Systems is a fully assembled and tested evaluation board for the MPQ4425BGQ-AEC1, a synchronous step-down LED driver IC. It delivers up to 1.5A output current across a 4V–36V input range, operates at 400kHz switching frequency, supports PWM dimming (100Hz–2kHz), and includes fault indication for LED open/short and thermal shutdown - designed for automotive LED lighting validation.

For engineers reviewing the EVQ4425B-QB-00A datasheet, EVQ4425B-QB-00A pinout, EVQ4425B-QB-00A application, or EVQ4425B-QB-00A equivalent, this board enables rapid characterization of MPQ4425BGQ-AEC1's efficiency, EMI performance (CISPR25 Class 5 compliant), dimming response, and fault recovery behavior under real-world automotive LED load conditions.

Technical Context

The EVQ4425B-QB-00A implements the MPQ4425BGQ-AEC1 in forced continuous conduction mode (FCCM) with internal 85mΩ high-side and 50mΩ low-side MOSFETs. It uses a 0.2V reference voltage for current regulation and features valley-current over-current protection with thermal shutdown and open/short LED fault detection.

Board-level design incorporates a 10µH power inductor (XAL4040-103MEB), input EMI filtering (2.2µH + 22µF/2.2µF capacitors), and a 3-resistor parallel network (R5/R6/R7 = 400mΩ each) to set 1.5A LED current. The EN/DIM pin accepts external PWM signals for dimming control, while /FAULT provides open-drain fault signaling.

Key Specifications

Availability

EVQ4425B-QB-00A is available at Aetrix Electronics and suitable for automotive LED headlamp validation, interior lighting prototyping, and adaptive driving beam (ADB) system development requiring stable component supply and production-grade EMI verification.

Supply support for EVQ4425B-QB-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 design expertise in DC/DC conversion, LED drivers, motor drivers, and battery management solutions.

The MPQ4425B product line delivers AEC-Q100 Grade 1 qualified synchronous buck LED drivers optimized for automotive exterior lighting, emphasizing high efficiency, fault resilience, and robust EMI performance in harsh environments.

FAQ

What input voltage range does the EVQ4425B-QB-00A support?

The board operates from 4V to 36V DC input, covering nominal 12V and 24V automotive systems, including cold-crank (down to ~4V) and transient overvoltage conditions up to 36V. Input filtering includes a 2.2µH EMI choke and bulk capacitance to maintain stability during fast transients.

How is LED current set on this evaluation board?

LED current is set by the parallel combination of R5, R6, and R7 (each 400mΩ, 1% tolerance), yielding an effective feedback resistance of 133mΩ. With the MPQ4425B's 0.2V internal reference, I_LED = 0.2V / 0.133Ω ≈ 1.5A. This configuration is pre-populated and verified for 1.5A operation.

Does the board support PWM dimming, and how is it implemented?

Yes - PWM dimming is implemented via the EN/DIM pin, which accepts external clock signals from 100Hz to 2kHz. The board routes this signal directly to the IC without additional conditioning, enabling precise duty-cycle control while maintaining constant current regulation during dimming transitions.

What fault protection features are demonstrated on the EVQ4425B-QB-00A?

The board demonstrates LED open-circuit, LED short-to-GND, and LED short-to-LED− fault detection via the open-drain /FAULT pin, which pulls low with 0.45V hysteresis. Thermal shutdown recovery and fault latching behavior are observable using oscilloscope waveforms provided in the reference design report.

Is the EVQ4425B-QB-00A compliant with automotive EMI standards?

Yes - the board meets CISPR25 Class 5 limits for both conducted (150kHz–108MHz) and radiated emissions (150kHz–1GHz, horizontal/vertical polarization), as validated in the official test report. Layout optimizations include split ground planes, controlled trace routing, and integrated EMI filters.

Can the board be used with different LED string configurations?

Yes - the board supports single- or multi-LED strings (e.g., 1× or 2× LEDs) by adjusting the feedback resistor network and selecting appropriate output capacitors. V_LED range is limited only by the 36V input and internal switch voltage rating; typical test cases include 3.2V (1 LED) and 6.4V (2 LEDs in series).