Monolithic Power Systems Inc. MP28266DL-LF-P

Overview

MP28266DL-LF-P from Monolithic Power Systems is a synchronous step-down DC-DC converter with integrated 120mΩ high-side and 20mΩ low-side MOSFETs, delivering up to 3A continuous output current from a 6V–21V input, fixed 500kHz switching frequency, and 0.6V ±2% internal reference-designed for compact power rails in DSL modems and set-top boxes.

For engineers reviewing the MP28266DL-LF-P datasheet, MP28266DL-LF-P pinout, MP28266DL-LF-P application, or MP28266DL-LF-P equivalent, key selection criteria include input voltage range (6–21V), AAM/CCM mode control via AAM pin, external sync capability (300kHz–2MHz), thermal shutdown (150°C), and QFN14 (3×4mm) package layout requirements for high-current SW/GND paths.

Technical Context

The MP28266 operates in peak-current-mode control with a fixed 500kHz oscillator, supporting external synchronization and adaptive asynchronous modulation (AAM) to optimize light-load efficiency. Its error amplifier compares FB voltage against a 0.6V reference and drives an internal compensation network that minimizes external components.

Internal bootstrap regulation maintains BST voltage ≥2.2V with 150mV hysteresis; under-voltage lockout activates at VIN <4.4V (falling) and releases at >5.5V (rising). Over-current protection uses hiccup-mode limiting triggered when FB drops below 70% of reference while inductor current exceeds 4.2A.

Key Specifications

Pinout & Package

MP28266DL-LF-P is housed in a thermally enhanced 3mm × 4mm QFN14 package with exposed thermal pad (internally unconnected; must be soldered to GND plane). Pin 1 is marked by index area; pins 2–5 and 12–13 are paralleled SW and GND terminals respectively for high-current routing.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP28266DL-LF-P, MP28164DJ-LF-Z trades input range and sync capability for smaller footprint and cost, while RT7295BGJ8F extends input voltage but increases component count and layout sensitivity due to external compensation.

Availability

MP28266DL-LF-P is available at Aetrix Electronics and suitable for DSL modems, cable modems, and set-top boxes requiring stable component supply, RoHS-compliant packaging, and production-ready thermal performance.

Supply support for MP28266DL-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 over two decades of innovation in DC-DC conversion and motor control.

The MP28266 belongs to MPS's high-efficiency synchronous buck converter product line, engineered for space-constrained broadband and video equipment demanding wide-input, low-noise, and thermally robust power delivery.

FAQ

What is the minimum recommended input capacitance for MP28266DL-LF-P?

A 22µF X5R/X7R ceramic capacitor is recommended for most applications, placed as close as possible to the IN and GND pins. For high-RMS current handling, select a part rated for ≥1.5A RMS ripple current. When using bulk electrolytic or tantalum capacitors, add a 0.1µF ceramic in parallel directly at the IC pins to suppress high-frequency noise.

How does the AAM pin affect light-load efficiency and output ripple?

Driving the AAM pin above 2.9V forces continuous conduction mode (CCM), improving transient response but increasing light-load quiescent current (0.7mA typ). Pulling AAM below 2.2V enables AAM mode, reducing Iq to 0.6mA typ but increasing output ripple due to discontinuous switching. Optimal bias (e.g., 2.5V) balances both metrics per application requirements.

Can MP28266DL-LF-P operate without an external bootstrap capacitor?

No. A 0.1µF ceramic capacitor between BST and SW pins is mandatory to generate the floating gate-drive voltage for the high-side MOSFET. Omitting it causes immediate failure of HS switching, resulting in no output regulation and potential damage due to shoot-through or excessive VSW ringing.

What is the maximum achievable output voltage with MP28266DL-LF-P?

The device supports output voltages up to 18V, limited by the absolute maximum rating of the FB pin (6V) and the internal 0.6V reference. Using a standard resistor divider, VOUT = 0.6V × (1 + R1/R2); for 18V output, R1/R2 ≈ 29, requiring precision resistors to maintain accuracy and stability across temperature.

Is thermal pad connection to PCB ground required for reliable operation?

Yes. The exposed thermal pad must be soldered to a solid GND copper pour with ≥4 thermal vias (0.3mm diameter) to achieve θ_JA = 48°C/W. Without this, junction temperature rises rapidly under 3A load, triggering thermal shutdown within seconds. The pad has no internal electrical connection-it serves purely for heat dissipation.

Does MP28266DL-LF-P support pre-biased output startup?

Yes. If the output is pre-biased at startup, the IC disables both HS and LS switches until the SS capacitor voltage exceeds the sensed FB voltage. This prevents reverse current flow through the low-side MOSFET and avoids output voltage collapse or overshoot during hot-insertion scenarios.