Monolithic Power Systems Inc. MPQ4425MGQB-Z

Overview

MPQ4425MGQB-Z from Monolithic Power Systems is a synchronous step-down LED driver IC with integrated 85mΩ/50mΩ MOSFETs, delivering 1.5A continuous output current across a 4V–36V input range, operating at a fixed 2.2MHz switching frequency, and qualified to AEC-Q100 Grade-1 for automotive lighting applications.

For engineers reviewing the MPQ4425MGQB-Z datasheet, MPQ4425MGQB-Z pinout, MPQ4425MGQB-Z application, or MPQ4425MGQB-Z equivalent, this device supports PWM dimming (100Hz–2kHz), features fault indication (/FAULT), internal soft-start (0.9ms), and CISPR25 Class 5 EMI compliance - critical for headlamp and DRL system design.

Technical Context

The MPQ4425MGQB-Z employs peak-current-mode control with internal 0.2V reference and valley-current detection for over-current protection. Its forced CCM operation ensures stable 2.2MHz switching from no-load to full-load, while frequency foldback reduces switching frequency to 1.1MHz above ~21V input or during fault conditions.

It integrates a 4.9V internal regulator powered from VIN, bootstrap circuitry with BST pin requiring external capacitor and optional 20Ω series resistor, and dual ground domains (AGND and PGND) internally connected but layout-isolated for noise control in high-dI/dt LED current paths.

Key Specifications

Pinout & Package

MPQ4425MGQB-Z is housed in a wettable flank QFN-13 package (2.5mm × 3mm, 0.5mm pitch) with exposed thermal pad, optimized for automated optical inspection (AOI) and enhanced solder joint reliability in automotive reflow processes.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPQ4425MGQB-Z, the MPQ4425AGQB-Z omits automotive qualification but retains identical performance, while the LM3409QMYX/NOPB trades integration for design flexibility - making the MPQ4425MGQB-Z optimal for space-constrained, certified automotive LED modules needing plug-and-play current regulation.

Availability

MPQ4425MGQB-Z is available at Aetrix Electronics and suitable for automotive daytime running lights, front fog lamps, and rear combination lamps requiring stable component supply with full AEC-Q100 traceability and long-term production support.

Supply support for MPQ4425MGQB-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 analog and power ICs, with core expertise in DC-DC conversion, LED drivers, and motor control solutions.

The MPQ4425M product line delivers AEC-Q100–qualified synchronous buck LED drivers targeting automotive exterior lighting applications where efficiency, EMI compliance, and functional safety diagnostics are mandatory.

FAQ

What is the minimum input voltage required for MPQ4425MGQB-Z to start switching?

The device incorporates an internal under-voltage lockout (UVLO) with a rising threshold of 3.5V. It will not initiate switching until the IN pin voltage exceeds this level. Below 3.5V, the IC remains in shutdown mode with quiescent current limited to 12μA, ensuring no unintended operation during battery brownout or cold-crank conditions.

Can MPQ4425MGQB-Z drive more than two series-connected LEDs?

Yes - the 36V maximum input rating allows driving longer LED strings, provided the total forward voltage remains below VIN minus dropout margin. For example, at 12V input, up to three 3.2V LEDs (9.6V total) can be driven with sufficient headroom; efficiency and thermal performance must be verified per application using Equation (1) and thermal resistance data (θ_JA = 60°C/W).

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

In normal operation, /FAULT is an open-drain output pulled high by an external resistor (e.g., 100kΩ to VCC). It transitions low only during confirmed faults: LED open circuit (no current flow), LED short (excessive current triggering OCP), or die temperature exceeding 170°C. The fault condition persists until the root cause is removed and the device resets after thermal cooldown or input cycle.

Is an external bootstrap diode required for reliable operation?

No - the MPQ4425MGQB-Z operates reliably with only the internal bootstrap circuit and external BST capacitor. An external diode (e.g., IN4148) is optional and recommended only when duty cycle exceeds 65%, as it improves high-duty-cycle efficiency by reducing BST capacitor discharge losses; it adds BOM cost and board area without benefit in typical DRL/fog lamp use cases.

What is the purpose of the NC pin (Pin 3), and how should it be handled on the PCB?

Pin 3 is a no-connect terminal with no internal connection or function. It must remain unconnected - neither tied to ground, power, nor left floating with parasitic coupling. PCB layout should omit any copper trace, solder mask opening, or via at this location to prevent accidental shorts or EMI coupling into adjacent high-speed nodes like SW or BST.

Does MPQ4425MGQB-Z support analog dimming via the FB pin?

No - the FB pin is strictly a current-sense feedback input referenced to the internal 0.2V comparator. Analog dimming is not supported. Brightness control is implemented exclusively via PWM applied to the EN/DIM pin (100Hz–2kHz), which directly modulates switching enable state and maintains constant current amplitude during active periods.

How is thermal performance affected by the wettable flank QFN package?

The wettable flank feature does not alter thermal resistance (θ_JA = 60°C/W, θ_JC = 13°C/W remain unchanged), but enables reliable solder joint formation and post-reflow AOI inspection - critical for detecting voids or insufficient solder in automotive production. This improves long-term thermal interface integrity under thermal cycling, indirectly sustaining rated power delivery over lifetime.