Monolithic Power Systems Inc. MP4581GN-P

Overview

MP4581GN-P from Monolithic Power Systems is a 100V-input, 0.8A synchronous step-down buck converter with integrated 625mΩ high-side and 265mΩ low-side MOSFETs, constant-on-time (COT) control, and configurable 100kHz–1MHz switching frequency. It delivers regulated 1V–30V output in SOIC-8EP for industrial power supplies, high-voltage battery packs, and printer power boards.

For engineers reviewing the MP4581GN-P datasheet, MP4581GN-P pinout, MP4581GN-P application, or MP4581GN-P equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, application-specific use cases, and two confirmed alternative parts with documented functional trade-offs.

Technical Context

The MP4581GN-P implements constant-on-time (COT) control with input-voltage feedforward to maintain stable switching frequency across 8V–100V input range while enabling fast transient response without external compensation. Its valley-current limiting and hiccup-mode short-circuit protection operate independently of load conditions.

It integrates internal soft-start (4.35ms), VCC LDO regulation (4.85V typical), and bootstrap gate drive for the high-side MOSFET-requiring only a 0.1μF BST–SW capacitor. The EN pin supports direct connection to VIN via resistor for automatic startup and tolerates up to 100V.

Key Specifications

Pinout & Package

MP4581GN-P is housed in an SOIC-8EP package (8-pin, exposed pad) with standard JEDEC MS-012 footprint and θ_JA = 38°C/W on 2-layer board. The exposed pad must be soldered to PCB ground plane for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP4581GN-P, MPQ4581GD-A adds automotive qualification without changing performance, while LM5164QPWPRQ1 trades COT simplicity and ultra-low IQ for current-mode flexibility and higher peak current tolerance - making it less optimal for space-constrained, always-on industrial nodes.

Availability

MP4581GN-P is available at Aetrix Electronics and suitable for industrial PLC power rails, high-voltage battery management systems, and printer mainboard power requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for MP4581GN-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 power management ICs, with over 20 years of leadership in integrated DC/DC converters and motor drivers.

The MP4581GN-P belongs to MPS's high-voltage buck converter product line, designed specifically for industrial and battery-powered systems demanding wide input range, high integration, and robust protection in compact SOIC packages.

FAQ

What is the minimum recommended input voltage for reliable startup?

The MP4581GN-P requires VIN ≥8V to exit under-voltage lockout and initiate switching. Below 8V, the internal VCC regulator cannot sustain control circuit operation, and EN activation will not result in output regulation. Startup is guaranteed at 8V across -40°C to +125°C ambient.

Can the MP4581GN-P operate with an output voltage lower than 1V?

No. The internal 1.00V reference voltage and FB comparator architecture limit the minimum regulated output to 1V. Attempting to set VOUT <1V via resistor divider results in loss of regulation, as the feedback loop cannot drive the error amplifier below its reference threshold.

How does the FREQ pin resistor value affect efficiency at full load?

A lower FREQ resistor (higher f_SW) increases MOSFET switching losses but reduces inductor ripple current and output capacitor RMS stress. At 0.8A load, peak efficiency (~92%) occurs near 400kHz; efficiency drops ~1.5% at 1MHz due to increased gate charge and transition losses.

Is the BST capacitor polarity-sensitive, and what dielectric is recommended?

Yes - the BST capacitor must be placed with correct orientation: positive terminal to BST pin, negative to SW pin. X7R or X5R ceramic dielectrics are mandatory; NP0/C0G types lack sufficient capacitance density, and tantalum or aluminum electrolytics introduce ESR-related instability and reliability risk.

Does the MP4581GN-P support pre-biased output startup?

Yes. Its monotonic soft-start architecture allows safe startup into pre-biased outputs up to 90% of target VOUT. The internal SS capacitor charges only if FB voltage is below the rising SS ramp, preventing reverse current flow and output voltage overshoot during hot-plug scenarios.

What thermal derating applies above 70°C ambient?

With θ_JA = 38°C/W on a 2-layer board, maximum continuous output current derates linearly from 0.8A at 25°C to ~0.55A at 70°C ambient. Above 70°C, thermal shutdown activates at 150°C junction temperature, with recovery at 125°C after hiccup delay.

How is short-circuit protection implemented during hiccup mode?

Upon short-circuit detection, the MP4581GN-P disables switching, discharges the soft-start capacitor, waits ~20ms, then reinitiates soft-start. This cycle repeats until fault clears. Hiccup mode limits average power dissipation to <150mW, preventing thermal damage during sustained output shorts.