Monolithic Power Systems Inc. MP28258DD-A-LF-P

Overview

MP28258DD-A-LF-P from Monolithic Power Systems is a synchronous step-down DC/DC converter delivering 3A continuous output current with 4.2V–20V input range, 0.815V–13V adjustable output, and Constant-On-Time (COT) control for fast transient response in networking and distributed power systems.

For engineers reviewing the MP28258DD-A-LF-P datasheet, MP28258DD-A-LF-P pinout, MP28258DD-A-LF-P application, or MP28258DD-A-LF-P equivalent, key selection criteria include hiccup-mode OCP, QFN12 (2×3mm) thermal performance (θJA = 70°C/W), PG open-drain timing (0.5ms delay), and bootstrap-driven high-side gate drive requiring external BST capacitor.

Technical Context

The MP28258DD-A-LF-P uses Constant-On-Time (COT) control with input-voltage feed-forward to maintain stable switching frequency across 4.2V–20V input, achieving fast load-step response without external compensation. Its integrated dual MOSFETs feature 120mΩ high-side and 50mΩ low-side R_DS(ON), enabling >90% efficiency at 1.2V/3A output.

It implements hiccup-mode over-current protection triggered when inductor current exceeds 4–5A and FB drops below 50% of reference (≈0.4V), followed by automatic soft-start retry. Power-good signaling provides 0.5ms delay between 90% V_FB detection and PG assertion, with 0.4V sink capability at 4mA.

Key Specifications

Pinout & Package

MP28258DD-A-LF-P is housed in a thermally enhanced QFN12 package (2mm × 3mm, 0.5mm pitch) with exposed thermal pad (Pin 2, 10, and exposed pad connected to SW). The package supports ≤1.8W continuous power dissipation at 25°C ambient (θ_JA = 70°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous step-down converter applications.

Compared with MP2330H, MP28258DD-A-LF-P offers proven hiccup-mode reliability in telecom infrastructure but lacks the newer IC's extended input range and lower IQ; versus RT7297B, it provides critical system-level features-adjustable output, PG signaling, and robust fault handling-essential for complex embedded power trees.

Availability

MP28258DD-A-LF-P is available at Aetrix Electronics and suitable for networking equipment power, distributed telecom PSU, industrial PLC I/O modules, and embedded computing boards requiring stable component supply with full RoHS compliance and tape-and-reel packaging.

Supply support for MP28258DD-A-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 MP28258 belongs to MPS's high-efficiency synchronous buck converter product line, engineered for fast transient response and minimal external component count in space-constrained industrial and communications power systems.

FAQ

What is the recommended input capacitor configuration for MP28258DD-A-LF-P?

Use a minimum 10µF X5R/X7R ceramic capacitor placed directly at the IN pin with short, wide traces and multiple vias to GND. For high-RMS input current applications, add a 47–100µF low-ESR aluminum polymer capacitor in parallel to handle bulk energy storage and reduce ripple-induced heating.

How does the hiccup-mode OCP behave during a sustained short circuit?

When output is shorted, MP28258DD-A-LF-P detects overcurrent and FB voltage collapse, disables switching, discharges the internal soft-start capacitor, waits ~10ms, then attempts soft-start again. This cycle repeats until fault clears, limiting average power dissipation to <0.5W and preventing thermal damage.

Can MP28258DD-A-LF-P operate with ceramic output capacitors only?

Yes, but external ramp compensation (R4/C4) is required on the FB pin to ensure stability in PWM mode. Ceramic caps lack ESR-based natural ramp; omitting ramp compensation causes subharmonic oscillation or jitter. Design equations in the datasheet (Section 11) specify R4/C4 values based on VIN, VOUT, and inductor value.

What is the function of the exposed thermal pad on the QFN12 package?

The exposed pad (connected internally to SW) serves as the primary thermal path and must be soldered to a dedicated PCB thermal plane with ≥4 thermal vias (0.3mm diameter) to an inner ground layer. It contributes >60% of total heat dissipation and is essential to meet θ_JA = 70°C/W specification.

Is MP28258DD-A-LF-P pin-compatible with MP28258DD?

Yes - both share identical QFN12 (2×3mm) footprint, pinout, and electrical interface. The only functional difference is OCP behavior: MP28258DD uses latch-off mode, while MP28258DD-A-LF-P uses hiccup mode. No layout change is needed for migration between them.

What is the maximum achievable output voltage accuracy over temperature?

Feedback voltage tolerance is ±1.5% (803–827mV) from –40°C to +85°C ambient. With 0.5% resistors in the FB divider and proper layout, total output voltage error remains within ±2.2% across full operating temperature and load range.

Does MP28258DD-A-LF-P support synchronization to an external clock?

No - it lacks an external sync input. Switching frequency is set solely by the resistor on the FREQ pin and varies slightly with input voltage due to COT architecture. For synchronized multi-phase operation, use MPQ4470 or MPQ4572 series instead.