Monolithic Power Systems Inc. MP4689DN-LF-P

Overview

MP4689DN-LF-P from Monolithic Power Systems is a 100V-input, 1A constant-current step-down LED driver IC with integrated high-side MOSFET (R_DS(ON) = 500 mΩ), hysteresis current-mode control, ±3% LED current accuracy, and 20 kHz PWM dimming support. It operates across 4.5–95 V input, delivers up to 95% efficiency, and targets automotive headlight modules, industrial high-bay lighting, and battery-powered emergency signage.

For engineers reviewing the MP4689DN-LF-P datasheet, MP4689DN-LF-P pinout, MP4689DN-LF-P application, or MP4689DN-LF-P equivalent, key selection criteria include its 200 mV feedback reference voltage, 170 µA quiescent current, thermal shutdown at 150°C, SOIC-8 EP package with exposed pad, and dedicated DIM/EN logic-level control inputs for robust lighting system integration.

Technical Context

The MP4689 employs adaptive hysteresis current-mode control with dual FB thresholds (V_FBL = 185 mV, V_FBH = 215 mV) to maintain 200 mV average sensing voltage across the external current-sense resistor-enabling ±3% LED current regulation without compensation components. Its internal 100 V-rated high-side switch integrates current limiting (2.9 A typ.) and short-circuit protection with 10 µs fault detection latency.

Operation relies on bootstrap-driven gate drive (BST–SW capacitor), UVLO (4.0 V rising / 3.65 V falling), and independent EN/DIM inputs with defined logic thresholds (VENH = 1.55 V, VDIMH = 1.15 V). Thermal shutdown includes 20°C hysteresis, and the IC sustains continuous operation from –40°C to +125°C junction temperature.

Key Specifications

Pinout & Package

The MP4689DN-LF-P is housed in an SOIC-8 with exposed pad (SOIC-8 EP), where the exposed pad must be soldered to a PCB ground plane for optimal thermal performance (θ_JC = 10°C/W). Pin 8 serves as both GND and thermal pad connection point.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage constant-current LED driver applications.

Compared with MPQ4689-AEC1, the MP4689DN-LF-P offers identical core regulation and pinout but omits automotive qualification-reducing cost for non-automotive applications. Versus LM3409HV, it trades external flexibility for integration density, eliminating gate driver design effort and reducing bill-of-materials count by four components.

Availability

MP4689DN-LF-P is available at Aetrix Electronics and suitable for automotive headlamp modules, industrial high-bay luminaires, and battery-powered emergency signage requiring stable component supply, long-lifecycle availability, and RoHS-compliant packaging.

Supply support for MP4689DN-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, and global manufacturing partnerships.

The MP4689 belongs to MPS's high-voltage LED driver product line, engineered specifically for robust, integrated constant-current regulation in harsh environments-including automotive, industrial, and outdoor lighting where input transients, thermal stress, and long service life are critical.

FAQ

What is the maximum allowable input voltage for continuous operation?

The MP4689DN-LF-P supports continuous operation up to 95 V input (VIN), with absolute maximum rating of 100 V. Operation above 95 V is not guaranteed per specifications and may reduce reliability or trigger UVLO shutdown depending on transient conditions.

Can the MP4689DN-LF-P drive multiple parallel LED strings?

No-it is designed for single-string constant-current operation. Driving parallel strings requires individual current-sense resistors and feedback paths per string, which the MP4689 does not support. For multi-string applications, use separate MP4689 units or a matrix driver architecture.

Is an external bootstrap diode required for normal operation?

An external bootstrap diode is optional and recommended only in specific cases: when VIN ≤ 5 V, when VOUT/VIN > 65%, or when switching above 1.5 MHz. Under standard 12–48 V input and 200–600 V LED string conditions, the internal bootstrap regulator suffices.

How is LED current accuracy affected by temperature?

The MP4689 maintains ±3% LED current accuracy over –40°C to +125°C junction temperature, verified by design and characterization. This is achieved through adaptive FB threshold adjustment that compensates for internal propagation delays and MOSFET R_DS(ON) drift.

What is the minimum recommended inductor value for 60 V input and 30 V LED string?

For VIN = 60 V, VOUT = 30 V, and 1 A LED current, the recommended inductor is ≥47 µH. Smaller values increase peak current stress and ripple; larger values reduce ripple but lower switching frequency-potentially increasing size and reducing transient response speed.

Does the MP4689DN-LF-P support analog dimming via the FB pin?

No-the FB pin is strictly a current-sense input with fixed 200 mV regulation target. Analog dimming is not supported. Brightness control must be implemented using the dedicated DIM pin with PWM signals or by modulating EN for on/off cycling.

What PCB layout practices are critical for thermal performance?

Thermal performance depends on soldering the exposed pad (Pin 8) to a solid copper ground plane using ≥4 thermal vias (15 mil barrel, 40 mil pitch), placing the input capacitor within 5 mm of VIN/SW/GND pins, and routing the FB trace away from noisy power loops-ideally on the opposite layer with ground plane shielding.