Monolithic Power Systems Inc. MP8675DN-LF

Overview

MP8675DN-LF from Monolithic Power Systems is a synchronous step-down DC/DC converter with integrated 100mΩ high-side MOSFET and external gate driver for low-side FET control. It delivers 6A continuous output current across 4.5V–42V input, operates at fixed 420kHz (synchronizable to 1.5MHz), and regulates output down to 0.8V. Used in flat-panel TV power rails where high efficiency and thermal robustness are critical.

For engineers reviewing the MP8675DN-LF datasheet, MP8675DN-LF pinout, MP8675DN-LF application, or MP8675DN-LF equivalent, key selection factors include its synchronizable gate driver architecture, cycle-by-cycle over-current latch-off protection, thermal shutdown at 150°C, and compatibility with low-ESR ceramic output capacitors in space-constrained industrial power designs.

Technical Context

The MP8675DN-LF implements peak-current-mode control with a fixed 420kHz oscillator, supporting external synchronization from 300kHz to 1.5MHz via the EN/SYNC pin. Its internal 5V VCC regulator powers the gate driver and error amplifier, with bootstrap charging managed through the BST–SW node.

It integrates a high-side MOSFET (R_DS(ON) = 100mΩ) and provides a dedicated BG driver output with 4Ω source / 1Ω sink impedance. Fault protection includes cycle-by-cycle current limiting (trip at 7.5–8.0A), UVLO (4.1V rising threshold), and thermal shutdown with hysteresis (150°C trip, ~140°C recovery).

Key Specifications

Pinout & Package

MP8675DN-LF is housed in an 8-pin SOIC package with exposed thermal pad (SOIC8E), optimized for surface-mount thermal dissipation on 4-layer PCBs (θ_JA = 50°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPQ8675GD-AEC1, the MP8675DN-LF offers identical performance at lower cost for commercial temperature applications; versus LM5116PWPR, it reduces component count and layout complexity for ≤42V inputs but lacks voltage scalability.

Availability

MP8675DN-LF is available at Aetrix Electronics and suitable for flat panel television power rails, digital set-top box core supplies, and broadband communications equipment requiring stable component supply across production lifecycles.

Supply support for MP8675DN-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 power ICs, headquartered in California and serving global industrial, computing, and consumer markets since 1997.

The MP8675 belongs to MPS's high-current synchronous buck controller product line, designed specifically for compact, thermally constrained power supplies in digital video and broadband infrastructure equipment.

FAQ

What is the minimum recommended input capacitance for MP8675DN-LF at 6A output?

A 22µF X5R or X7R ceramic capacitor is specified for 6A applications to suppress input surge current and high-frequency switching noise. This value assumes typical board layout and 4.5–42V input range; larger values may be needed if input source impedance exceeds 50mΩ at 420kHz.

Can MP8675DN-LF operate without an external synchronous MOSFET?

No - the MP8675DN-LF requires an external low-side MOSFET driven by the BG pin. It does not include a synchronous rectifier; omitting the external FET will cause failure due to lack of freewheeling path and excessive power dissipation in the inductor and internal switch.

How is output voltage adjusted, and what is the tolerance impact of resistor selection?

Output voltage is set by a resistor divider from VOUT to GND, with FB referenced to 0.808V (typ). Using 1% tolerance resistors (e.g., 40.2kΩ R1 and 13kΩ R2 for 3.3V) limits total output error to ±1.5% including reference drift and divider ratio error across temperature.

Does MP8675DN-LF support forced PWM mode or discontinuous conduction mode (DCM)?

No - the MP8675DN-LF operates exclusively in continuous conduction mode (CCM) with peak-current-mode control. It does not feature pulse-skipping or DCM modes; light-load efficiency relies on reduced switching losses rather than mode transition.

What is the purpose of the exposed thermal pad, and how must it be connected?

The exposed pad is electrically connected to GND and serves as the primary thermal path. It must be soldered to a dedicated PCB copper pour tied to the system ground plane using ≥4 thermal vias (0.3mm diameter) to achieve θ_JA = 50°C/W and sustain 6A continuous operation at TA = +85°C.

Is an external bootstrap diode required for reliable operation?

An external bootstrap diode (e.g., IN4148) is optional and recommended only when VOUT ≥ 3.3V and duty cycle >65% (i.e., VOUT/VIN > 0.65), such as 5V output from 7V input. It improves BST capacitor recharge efficiency but is not required for standard 3.3V/12V operation.

What happens during thermal shutdown, and how does recovery occur?

At 150°C junction temperature, the device disables switching and holds EN/SYNC and BG outputs low. Recovery occurs automatically when die temperature falls below ~140°C; no external reset is needed, but output voltage will remain unregulated until full restart sequence completes.