Monolithic Power Systems Inc. MP4425AGQB-Z

Overview

MP4425AGQB-Z from Monolithic Power Systems is a synchronous step-down white LED driver IC with integrated 85mΩ/50mΩ MOSFETs, delivering up to 1.5A output current across 4V–36V input, operating at 2.2MHz fixed frequency, and featuring PWM dimming (100Hz–2kHz), fault indication (/FAULT), and CISPR25 Class 5 EMI compliance for automotive LED lighting.

For engineers reviewing the MP4425AGQB-Z datasheet, MP4425AGQB-Z pinout, MP4425AGQB-Z application, or MP4425AGQB-Z equivalent, key selection criteria include its forced-CCM operation, valley-current-detect OCP, 0.2V reference voltage for precise current regulation, thermal shutdown (170°C), and QFN-13 (2.5mm×3mm) package with exposed PGND pads for thermal management.

Technical Context

The MP4425AGQB-Z employs peak-current-mode control with internal 2.2MHz oscillator and frequency foldback to 1.1MHz above 21V input, ensuring stable regulation across wide VIN. Its integrated high-side and low-side MOSFETs enable synchronous rectification, while the bootstrap circuit (BST pin + external capacitor/resistor) sustains gate drive under high-duty-cycle conditions.

Current regulation is achieved via feedback of LED current through an external sense resistor to the FB pin, referenced to a trimmed 0.2V internal voltage. Fault protection includes open/short LED detection and thermal shutdown with 30°C hysteresis, signaled via open-drain /FAULT pin with 4mA sink capability at 0.4V.

Key Specifications

Pinout & Package

MP4425AGQB-Z is housed in a thermally enhanced QFN-13 package (2.5mm × 3mm, 0.5mm pitch) with exposed PGND pads on the bottom for efficient heat dissipation. The package supports reflow soldering per JEDEC J-STD-020 and requires controlled PCB layout with multiple vias to inner ground planes.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT3966EFE#PBF and TPS92692QPWPRQ1, MP4425AGQB-Z offers the smallest footprint and lowest BOM cost for 36V-class automotive LED applications due to its fully integrated FETs, native PWM dimming on EN/DIM, and optimized 2.2MHz operation-making it ideal where space, EMI, and production cost are primary constraints.

Availability

MP4425AGQB-Z is available at Aetrix Electronics and suitable for automotive LED lighting, commercial interior fixtures, industrial machine vision illuminators, and heavy-duty vehicle signaling systems requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP4425AGQB-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 core expertise in DC-DC conversion, LED drivers, and motor control solutions for automotive, industrial, and consumer markets.

The MP4425A product line delivers highly integrated, high-frequency LED drivers targeting space-constrained automotive lighting applications-designed to replace discrete buck controllers and external MOSFETs while meeting stringent EMI and thermal requirements.

FAQ

What is the recommended input capacitor configuration for MP4425AGQB-Z?

Use a parallel combination: a bulk 4.7–10µF X5R/X7R ceramic capacitor (50V rating) plus a 0.1µF 0603 ceramic capacitor placed directly between IN and PGND pins. The small capacitor must be located within 2mm of the pins to suppress high-frequency switching noise. Total RMS current rating should exceed 0.75A for 1.5A LED loads.

Can MP4425AGQB-Z drive more than 1.5A LED current?

No-its internal MOSFETs and thermal design are rated for 1.5A continuous output. Attempting higher current causes thermal shutdown activation at 170°C junction temperature. For >1.5A, use parallel MP4425AGQB-Z units with current-sharing resistors or select a higher-current driver like MPQ4425HG-A.

How does the /FAULT pin behave during normal operation versus fault conditions?

During normal operation, /FAULT remains high-impedance (open-drain), allowing external pull-up to hold it at logic high. When LED open, short, or thermal shutdown occurs, the internal MOSFET pulls /FAULT to ≤0.4V with 4mA sink capability-providing a clean digital fault flag for microcontroller monitoring without additional level-shifting.

Is external bootstrap diode necessary for MP4425AGQB-Z?

An external bootstrap diode (e.g., 1N4148) is optional but recommended when duty cycle exceeds 65%, such as in 12V→5V LED string applications. It improves efficiency by reducing BST capacitor charging losses. The internal bootstrap circuit remains fully functional without it for lower-duty-cycle designs.

What is the minimum PWM dimming frequency supported, and how is dimming depth controlled?

The minimum supported PWM dimming frequency is 100Hz, with maximum of 2kHz. Dimming depth is linearly proportional to PWM duty cycle applied to the EN/DIM pin-e.g., 10% duty yields ~10% average LED current. Minimum pulse width must exceed 2ms if applied before soft-start completion.

Does MP4425AGQB-Z support analog dimming via the FB pin?

No-FB is strictly a current-sense feedback input referenced to 0.2V. Analog dimming is not supported. Brightness control is exclusively via PWM applied to EN/DIM or external current-source modulation of the R_FB node (not recommended per datasheet).

What PCB layout practices are critical for thermal performance?

Maximize thermal relief using ≥4-layer stackup with dedicated inner ground plane; connect all PGND pins (11–13) to this plane via ≥6 thermal vias (0.3mm diameter); place input capacitors within 3mm of IN/PGND; and avoid routing SW/BST traces near FB or AGND to prevent noise coupling into current regulation loop.