Monolithic Power Systems Inc. MP2108DQ-LF-P

Overview

MP2108DQ-LF-P from Monolithic Power Systems is a 2A, 740kHz synchronous buck converter in a 3mm × 3mm QFN-10 package, designed for space-constrained low-voltage DC/DC conversion. It integrates 160mΩ (low-side) and 190mΩ (high-side) MOSFETs, supports 2.6V–6V input, delivers regulated output down to 0.9V, and features cycle-by-cycle current limiting and thermal shutdown-used in handheld computing and compact camera power rails.

For engineers reviewing the MP2108DQ-LF-P datasheet, MP2108DQ-LF-P pinout, MP2108DQ-LF-P application, or MP2108DQ-LF-P equivalent, key selection criteria include its 740kHz fixed-frequency current-mode control, integrated power switches, soft-start timing via external capacitor, and thermal performance in QFN packaging for >1.5A loads.

Technical Context

The MP2108DQ-LF-P implements peak current-mode control with an internal 0.9V feedback reference and transconductance error amplifier (G_EA = 450 μA/V). Its 740kHz oscillator enables compact LC filtering, and the bootstrap gate drive (BST pin + 10nF capacitor) sustains high-side N-MOSFET operation across duty cycles up to 85%.

It embeds an internal 2.4V LDO regulator (VREF pin), undervoltage lockout (2.2V threshold, 100mV hysteresis), and dual current limits: 2.5–3.5A source (high-side) and 350mA sink (low-side). Thermal shutdown activates at 160°C, and θ_JA is 50°C/W in the QFN-10 package.

Key Specifications

Pinout & Package

MP2108DQ-LF-P uses a RoHS-compliant, thermally enhanced 3mm × 3mm QFN-10 package with exposed thermal pad on underside. Pin 1 is marked by dot; pins numbered counterclockwise. 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 RT6220AGQW and TPS62231DRVR, MP2108DQ-LF-P offers optimal balance of 2A capability, 740kHz frequency, integrated LDO, and QFN thermal performance - making it ideal for cost-sensitive, space-constrained 2.6–6V input systems needing robust, self-contained regulation without external bias rails.

Availability

MP2108DQ-LF-P is available at Aetrix Electronics and suitable for handheld computing, digital imaging, SOHO networking, and Mini-PCIe peripheral power applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP2108DQ-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 mixed-signal ICs for power management, motion control, and automotive applications.

The MP2108 belongs to MPS's mainstream synchronous buck converter product line, engineered for compact, efficient DC/DC conversion in portable and embedded systems where thermal density, solution size, and ease of design-in are critical.

FAQ

What is the minimum recommended output capacitor for stable operation?

A 22µF X5R/X7R ceramic capacitor is recommended for most applications. Its low ESR ensures minimal output ripple (<15mV at 2A) and contributes a dominant pole for loop stability. If using tantalum (e.g., 47µF/300mΩ), add C4 (e.g., 750pF) in parallel with R3 to compensate the ESR zero per Table 1 in the datasheet.

Can MP2108DQ-LF-P operate with a 2.5V input supply?

Yes - the absolute minimum input is 2.6V per datasheet specifications. At 2.5V, UVLO will hold the device in shutdown (RUN remains inactive) because the 2.2V UVLO threshold is exceeded by only 0.3V, below required headroom. Reliable operation begins at VIN ≥ 2.6V.

How is the soft-start duration calculated for a given capacitor value?

Soft-start time t_SS (ms) = 0.45 × C₅ (nF). For example, a 10nF capacitor yields ~4.5ms ramp time. To achieve 8ms, use C₅ = 22nF. The internal 2μA current source linearly charges the capacitor, scaling the FB reference from 0V to 0.9V over t_SS.

Is an external bootstrap diode required for 3.3V output operation?

An external BST diode (e.g., IN4148) is recommended when V_OUT = 3.3V and duty cycle exceeds 65% (i.e., V_IN < 5.08V). It improves high-side gate drive margin by clamping BST to V_OUT, preventing bootstrap capacitor discharge during high-duty cycles.

What is the maximum allowable output voltage ripple at 2A load?

Measured ripple is typically <12mV_pp at 2A with 22µF ceramic output cap and 5µH inductor. Ripple depends on f_SW, L, C_OUT, and ESR: VRIPPLE ≈ (ΔI × ESR) + (ΔI × t_ON) / (8 × C_OUT). For <10mV target, reduce ESR with parallel capacitors or increase C_OUT to 47µF.

Does the MP2108DQ-LF-P support adjustable switching frequency?

No - the oscillator is factory-trimmed to 740kHz (620–920kHz range over temperature and process). Frequency cannot be adjusted externally. This fixed frequency simplifies EMI filtering and eliminates need for external timing components.

How should the exposed thermal pad be connected on the QFN package?

The exposed pad must be soldered to a solid copper pour tied to PGND. Use ≥4 thermal vias (0.3mm diameter) connecting pad to inner ground plane. Do not float or connect to SGND - this ensures both thermal dissipation (θ_JA = 50°C/W) and low-impedance power return path.