Monolithic Power Systems Inc. EVQ4425B-J-00A

Overview

EVQ4425B-J-00A from Monolithic Power Systems is a fully assembled and tested evaluation board for the MPQ4425BGJ-AEC1 synchronous step-down LED driver IC, designed to deliver up to 1.5A output current from a 4V–36V input range in automotive LED lighting applications. It implements PWM dimming (100Hz–2kHz), forced CCM mode, 400kHz switching frequency, and features fault indication for LED open/short and thermal shutdown.

For engineers reviewing the EVQ4425B-J-00A datasheet, EVQ4425B-J-00A pinout, EVQ4425B-J-00A application, or EVQ4425B-J-00A equivalent, this board enables rapid validation of the MPQ4425BGJ-AEC1's high-efficiency LED driving capability, CISPR25 Class 5 EMI compliance, and AEC-Q100 Grade 1 reliability under real-world load conditions including 2-series white LED strings.

Technical Context

The EVQ4425B-J-00A implements the MPQ4425BGJ-AEC1 IC in a TSOT23-8 package with integrated 85mΩ high-side and 50mΩ low-side MOSFETs, enabling >94% peak efficiency at 12V_IN/6.4V_LED/1.5A. Its feedback reference voltage is fixed at 0.2V, and output current is set via external R_FB per I_LED = 0.2V / R_FB.

Board-level design includes dual-input filtering (V_IN/V_EMI), 2.2μH and 10μH power inductors, 22μF bulk input capacitance, and dedicated test points for EN/DIM, /FAULT, and FB. It supports both input-voltage and enable-controlled startup/shutdown, with validated waveforms for PWM dimming, LED open/short recovery (<40μs), and thermal fault response.

Key Specifications

Availability

EVQ4425B-J-00A is available at Aetrix Electronics and suitable for automotive headlamp development, interior ambient lighting qualification, and exterior signal lamp prototyping requiring stable component supply and pre-validated EMI performance.

Supply support for EVQ4425B-J-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 solutions, with over two decades of expertise in DC/DC conversion, LED drivers, and motor control ICs.

The MPQ4425B-AEC1 product line targets automotive LED lighting systems, delivering high-efficiency, AEC-Q100-compliant, and EMI-optimized step-down regulation with integrated power stages and robust fault protection.

FAQ

What is the purpose of the VEMI input terminal on the EVQ4425B-J-00A?

The VEMI terminal provides a dedicated low-inductance path for EMI filtering capacitors, decoupling high-frequency noise before it enters the main VIN rail. When used with the onboard BLM41PG181SN1L ferrite bead and 22μF CIN5 capacitor, it reduces common-mode conducted emissions to meet CISPR25 Class 5 limits-especially critical above 24V input.

How is output current set and verified on this evaluation board?

Output current is set by the parallel combination of R5 (200kΩ), R6, R7, and R8 (each 400mΩ), yielding R_FB ≈ 133mΩ. With the IC's 0.2V reference, I_LED = 0.2V / 133mΩ = 1.5A. Verification is performed using the onboard current-sense resistors and oscilloscope measurements of inductor current ripple and steady-state LED current.

Does the board support analog dimming or only PWM dimming?

The EVQ4425B-J-00A supports PWM dimming only, applied directly to the EN/DIM pin with an external 100Hz–2kHz clock signal. Analog dimming is not supported-the IC lacks a dedicated I_ADJ or CTRL pin, and its internal reference is fixed at 0.2V with no programmable gain or offset adjustment.

What fault conditions trigger the /FAULT pin, and how is it implemented?

The open-drain /FAULT pin pulls low during LED open circuit, LED short-to-GND, LED short-to-V_OUT, or thermal shutdown (>150°C junction). It is electrically isolated from the main power path and routed to a 2.54mm test point for logic analyzer monitoring, enabling real-time system-level fault logging without additional circuitry.

Can the switching frequency be adjusted, and if so, how?

No, the switching frequency is fixed at 400kHz and not user-adjustable. The MPQ4425BGJ-AEC1 does not include an RT resistor pin or frequency-selection bits; frequency is internally trimmed and guaranteed across temperature and process variation. Board-level components (e.g., L1/L2, CIN values) are optimized for this fixed frequency.

Is thermal management provided on the evaluation board, and how is it validated?

Yes-thermal management relies on the MPQ4425BGJ-AEC1's internal thermal shutdown (150°C) and the board's 2-layer PCB layout with exposed copper pads under U1 and power inductors. Thermal performance is validated via IR imaging during 1.5A continuous operation at 36V_IN, showing <25°C rise above ambient at 25°C ambient and natural convection.