Monolithic Power Systems Inc. MP3425DL-LF-P

Overview

MP3425DL-LF-P from Monolithic Power Systems is a current-mode 3.5A, 55V boost converter IC with integrated 90mΩ MOSFET, programmable switching frequency (300kHz–2MHz), and adjustable UVLO/soft-start. It operates from 3.1V–22V input and delivers up to 48V/350mA from 12V, used in telecom power supplies and microphone bias generation.

For engineers reviewing the MP3425DL-LF-P datasheet, MP3425DL-LF-P pinout, MP3425DL-LF-P application, or MP3425DL-LF-P equivalent, key selection criteria include its 3.5A internal switch R_DS(on), 1.225V feedback reference, 5μA soft-start current, thermal shutdown at 160°C, and QFN-14 (3×4mm) package with exposed pad for thermal management.

Technical Context

The MP3425DL-LF-P implements peak-current-mode control with a transconductance error amplifier (G_EA = 160μA/V, A_VEA = 300V/V) and internal 0.5V-regulated FSET pin enabling precise frequency programming via external resistor. Its COMP pin supports two-pole, one-zero compensation for stability across ceramic output capacitors.

It integrates undervoltage lockout with 250mV hysteresis, micropower shutdown (<1μA), and cycle-by-cycle current limiting. The 14-pin QFN exposes PGND on pins 4–6 and the bottom EP pad, separating power and analog grounds (AGND at pin 11) to minimize noise coupling into the 1.225V FB reference path.

Key Specifications

Pinout & Package

The MP3425DL-LF-P is housed in a thermally enhanced 14-pin QFN package (3mm × 4mm, 0.75mm height) with an exposed power ground pad (EP) for low θ_JA = 50°C/W. Pin 1 is marked by a corner chamfer per JEDEC MO-229 VEED-5.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar boost converter applications.

Compared with TPS61088RHLR and LT3467EDE#TRPBF, the MP3425DL-LF-P uniquely balances 3.5A capability, full programmability (f_SW, UVLO, SS), and QFN thermal performance-making it optimal for mid-power telecom and industrial boost applications requiring design flexibility and thermal robustness.

Availability

MP3425DL-LF-P is available at Aetrix Electronics and suitable for telecom power supplies, automotive camera modules, audio phantom power generation, and industrial sensor excitation requiring stable component supply across extended temperature ranges.

Supply support for MP3425DL-LF-P 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 design centers in the US, China, and Taiwan.

The MP3425 belongs to MPS's high-voltage boost converter product line, engineered for applications demanding regulated high-voltage rails from low-to-mid input sources-including telecom infrastructure, automotive infotainment, and precision instrumentation.

FAQ

What is the maximum output voltage achievable with MP3425DL-LF-P?

The MP3425DL-LF-P supports output voltages up to 55V, as defined by its absolute maximum SW pin rating. In practical operation, stable regulation up to 48V is confirmed in the datasheet's typical application (VIN = 12V → VOUT = 48V @ 350mA). Exceeding 48V requires careful layout, low-ESR output capacitors rated ≥63V, and verification of loop stability at reduced duty cycles.

How is switching frequency programmed on the MP3425DL-LF-P?

Switching frequency is set by connecting a resistor (R_FSET) from pin 14 (FSET) to AGND. The FSET pin maintains a regulated 0.5V, and the current sourced (I_FSET) linearly determines f_SW: f_SW(MHz) ≈ 0.86 / R_FSET(kΩ). For example, 66.5kΩ yields ~1.3MHz. Table 1 in the datasheet lists standard resistor values and corresponding frequencies from 260kHz to 2.37MHz.

Can the MP3425DL-LF-P operate with ceramic output capacitors only?

Yes-the MP3425DL-LF-P is explicitly designed for ceramic output capacitors. Its transconductance error amplifier and compensation architecture (two poles, one zero) stabilize loops using low-ESR ceramics (4.7–22μF typical). The datasheet confirms stability with 4.7μF X7R ceramics and provides recommended R_COMP/C_COMP values in Table 2 for common VIN/VOUT combinations.

What is the purpose of the separate AGND and PGND pins?

AGND (pin 11) serves as the quiet analog reference for FB, COMP, SS, and FSET-minimizing noise injection into the feedback and compensation paths. PGND (pins 8–10 + EP) carries high di/dt switching currents from SW and VIN. Separating these grounds prevents voltage spikes on PGND from modulating the 1.225V reference or COMP node, preserving regulation accuracy and loop stability.

Does MP3425DL-LF-P support automatic restart after thermal shutdown?

Yes-the MP3425DL-LF-P features automatic thermal shutdown recovery. When junction temperature reaches 160°C, the IC disables switching and halts power delivery. Once the die cools below the hysteresis threshold (~150°C), normal operation resumes without requiring an EN toggle or power cycle. This behavior is inherent to the internal thermal protection circuitry and requires no external components.

How is UVLO hysteresis implemented on the EN pin?

UVLO hysteresis is achieved via a 4μA current sink on the EN pin during power-up. As VIN rises, the EN voltage follows a resistor divider-but the 4μA sink pulls additional current through the upper resistor, raising the effective turn-on threshold. Once enabled (~1.5V), the sink turns off, so the falling threshold is determined solely by the resistor divider, creating hysteresis equal to 4μA × R_upper.

What is the minimum recommended input capacitance?

The datasheet specifies a minimum input capacitance of 4.7μF, using low-ESR ceramic, tantalum, or electrolytic types. A 0.1μF ceramic capacitor should be placed immediately adjacent to the VIN and AGND pins for high-frequency decoupling, while the bulk capacitor (≥4.7μF) may be located nearby. Total RMS current rating must exceed the inductor's peak-to-peak ripple current to prevent overheating.