Monolithic Power Systems Inc. MP2905EK-LF

Overview

MP2905EK-LF from Monolithic Power Systems is a hysteretic voltage-mode synchronous step-down controller IC designed for high-current point-of-load regulation. It operates from 3V to 28V input, delivers adjustable output from 0.6V to 0.9×VIN, supports 200–500kHz switching frequency, integrates internal 5V LDO (REF), and features lossless peak current sensing via ILIM pin for hiccup-mode overcurrent protection - used in GPU power rails and motherboard VRMs.

For engineers reviewing the MP2905EK-LF datasheet, MP2905EK-LF pinout, MP2905EK-LF application, or MP2905EK-LF equivalent, key selection criteria include its wide-input hysteretic control architecture, MSOP-10 package thermal performance (θJA = 150°C/W), soft-start programmability via SS capacitor, FB reference accuracy (±1.17% at 0.6V), and gate-driver timing specs (HG/LG dead time = 40ns, min on-time = 100ns).

Technical Context

The MP2905EK-LF implements a fixed-hysteresis voltage-mode control loop comparing FB against a ramped SS voltage with 20mV hysteresis, eliminating need for external compensation. Its internal 5V LDO (REF) powers all circuitry and remains functional across full 3–28V input range, enabling stable operation even below 5V VIN.

Current limiting uses lossless sensing: a resistor between ILIM and high-side MOSFET drain sets threshold via internal 50µA current sink; fault triggers adaptive hiccup mode with 250nA SS discharge. Overvoltage protection latches HG low/LG high when FB exceeds 750mV.

Key Specifications

Pinout & Package

MP2905EK-LF is housed in a thermally enhanced 10-pin MSOP package (MSOP-10-EP) with exposed pad connected to GND (Pin 4) for improved heat dissipation. Package dimensions: 3.0mm × 3.0mm × 1.0mm, θJA = 150°C/W on 4-layer JEDEC board.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP2905EK-LF, MP2918EK-LF offers higher integration and precision for next-gen compute loads, while RT8208GSP trades transient speed for predictable EMI and design familiarity in legacy systems.

Availability

MP2905EK-LF is available at Aetrix Electronics and suitable for graphics card power supplies, motherboard VRMs, and set-top box SoC regulation requiring stable component supply across extended temperature ranges (–40°C to +85°C).

Supply support for MP2905EK-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 Kirkland, WA, with global design and support centers.

The MP2900 series targets high-efficiency, high-current DC-DC conversion in computing and communications infrastructure, emphasizing hysteretic control for minimal external components and fast transient response.

FAQ

What is the minimum recommended output capacitor for stable MP2905EK-LF operation at 12A?

A minimum of 100µF ceramic (X7R) plus 330µF bulk capacitance is specified for 12A operation per the typical application circuit. This ensures output ripple stays below 18mV and maintains feed-forward capacitor stability. Lower ESR values reduce voltage deviation during load transients, and adding a 10Ω/1µF RC filter from VOUT to GND improves regulation under high-ESR conditions.

Can MP2905EK-LF operate with input voltage below 5V?

Yes - MP2905EK-LF functions from 3V to 28V input. Below 5V, the internal REF LDO output drops linearly but remains sufficient to power control circuitry. Efficiency decreases due to reduced gate-drive voltage margin, and soft-start time increases slightly as REF voltage scales with VIN. No external bias is required.

How is current limit set using the ILIM pin?

A resistor connects ILIM to the high-side MOSFET drain. An internal 50µA current sink develops a voltage drop across this resistor, which is compared to the MOSFET's V_DS. When V_DS exceeds the ILIM-set threshold, peak current limiting activates. Recommended R_ILIM range is 1kΩ–8kΩ, calculated as R_ILIM = V_DS(MAX)/50µA, where V_DS(MAX) = I_PEAK × R_DS(ON).

Does MP2905EK-LF require an external Schottky diode on the BST pin?

No - MP2905EK-LF contains an internal BST regulator and does not require an external Schottky diode. A 0.1µF ceramic capacitor must be placed between BST and SW pins to provide charge storage for high-side gate drive. This simplifies layout and eliminates reverse-recovery losses associated with discrete diodes.

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

When junction temperature reaches 140°C (typ), internal thermal protection disables HG and LG drivers and halts switching. The device remains latched off until temperature falls to ~120°C (20°C hysteresis), at which point normal operation resumes automatically. No external reset is needed, and the cycle repeats if thermal limits are re-exceeded.

Is pre-bias startup supported, and how does it behave?

Yes - MP2905EK-LF supports pre-bias startup. If FB voltage exceeds SS at power-on, HG and LG remain inactive until SS rises above FB. During this period, the SS capacitor discharges via a 250nA internal current sink until SS falls below 50mV, then ramps up normally, allowing safe tracking of existing output voltage without reverse current.

What is the maximum achievable output current with MP2905EK-LF?

MP2905EK-LF itself does not limit output current; it controls external high-side and low-side MOSFETs. In validated reference designs, it delivers 12A continuously (Figure 3) and 25A with optimized layout and MOSFET selection (Figure 4). Achievable current depends on MOSFET R_DS(ON), thermal design, and PCB copper area - not the controller's intrinsic rating.