Monolithic Power Systems Inc. MP8670DN-LF

Overview

MP8670DN-LF from Monolithic Power Systems is a synchronous step-down DC/DC converter with integrated 50mΩ high-side MOSFET and external low-side gate driver, delivering 6A continuous output current across 4.5V–30V input range, fixed 420kHz switching frequency, and adjustable 0.8V reference output voltage. It targets power rails in digital set-top boxes, flat-panel displays, and broadband communication equipment requiring high efficiency and thermal robustness.

For engineers reviewing the MP8670DN-LF datasheet, MP8670DN-LF pinout, MP8670DN-LF application, or MP8670DN-LF equivalent, key selection criteria include its synchronizable gate driver (300kHz–1.5MHz), cycle-by-cycle over-current protection, thermal shutdown at 150°C, and compatibility with low-ESR ceramic output capacitors in compact SOIC8E packages.

Technical Context

The MP8670DN-LF implements peak current-mode control with a fixed 420kHz internal oscillator, supporting external synchronization up to 1.5MHz via the EN/SYNC pin. Its functional block includes an internal 5V VCC regulator, error amplifier with 0.808V typical feedback reference, and dedicated bootstrap circuitry for driving external synchronous rectifiers.

It integrates a high-side MOSFET with 50mΩ R_DS(ON) and delivers gate drive signals through the BG pin while monitoring switch current via internal sensing. Protection features include under-voltage lockout (4.1V rising threshold), hiccup-mode short-circuit recovery, and thermal shutdown with 140°C hysteresis.

Key Specifications

Pinout & Package

MP8670DN-LF is housed in a thermally enhanced 8-pin SOIC package with exposed pad (SOIC8E), optimized for PCB heat dissipation via soldered thermal pad connection to internal ground plane.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous buck controller applications.

Compared with MPQ8670GD-AEC1, the MP8670DN-LF offers identical performance in commercial temperature grade but lacks automotive qualification; versus RT7297BZSP, it adds synchronization, hiccup-mode protection, and tighter feedback accuracy-critical for noise-sensitive or mission-critical systems.

Availability

MP8670DN-LF is available at Aetrix Electronics and suitable for digital set-top boxes, flat panel displays, broadband communications infrastructure, and industrial video recorders requiring stable component supply, RoHS-compliant packaging, and long-term lifecycle support.

Supply support for MP8670DN-LF 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 mixed-signal ICs for power management, motion control, and automotive applications.

The MP8670 belongs to MPS's high-current synchronous buck converter product line, designed specifically for space-constrained, thermally demanding applications in consumer electronics and communications equipment where integration, efficiency, and reliability are paramount.

FAQ

What is the minimum recommended input capacitance for MP8670DN-LF at 6A output?

A 22µF X5R/X7R ceramic capacitor is recommended for 6A output applications. This value ensures low impedance at the 420kHz switching frequency, suppresses input surge current, and maintains stability under transient load steps. Larger values improve hold-up time but are not required for basic operation.

Can MP8670DN-LF operate without an external synchronous MOSFET?

No. The MP8670DN-LF integrates only a high-side MOSFET and requires an external low-side MOSFET driven by the BG pin. Omitting the external FET disables synchronous rectification, causing excessive conduction loss and potential thermal failure under load.

How does the EN/SYNC pin function in synchronization mode?

In sync mode, the EN/SYNC pin accepts external clock signals from 300kHz to 1.5MHz. The internal oscillator aligns its rising edge to the external clock's rising edge. The pin must be driven with CMOS-compatible logic levels; no pull-up or pull-down is required beyond the external clock source.

What is the purpose of the BST capacitor, and what value is recommended?

The BST capacitor forms a floating supply for the high-side gate driver. It is connected between BST and SW pins. A 0.1µF to 1µF ceramic capacitor is recommended; 0.22µF is typical. With optional external bootstrap diode (e.g., IN4148), values ≥0.47µF improve efficiency at high duty cycles (>65%).

Does MP8670DN-LF support adjustable switching frequency?

No. It has a fixed 420kHz internal oscillator but supports external synchronization from 300kHz to 1.5MHz via the EN/SYNC pin. Frequency adjustment is achieved only by injecting an external clock-not by resistor or capacitor programming.

What thermal derating applies to the 6A output rating?

The 6A rating assumes proper PCB thermal design: exposed pad soldered to ≥1in² copper area with ≥4 thermal vias. At +85°C ambient, output current must be reduced to ~4.5A per θ_JA = 50°C/W and P_D(MAX) = (150°C − 85°C)/50°C/W = 1.3W, limiting practical dissipation.

Is an external bootstrap diode required for normal operation?

No. The internal bootstrap charging circuit operates reliably without external diodes. An external diode (e.g., IN4148) is optional and recommended only when V_OUT is 3.3V or 5V and duty cycle exceeds 65%, to reduce BST capacitor discharge losses and improve efficiency by ~0.5–1.2%.