Monolithic Power Systems Inc. MPM3805GQB-P

Overview

MPM3805GQB-P from Monolithic Power Systems is a synchronous step-down DC-DC power module with integrated inductor and MOSFETs, delivering 0.6A continuous output current from a 2.5V–6V input. It regulates output down to 0.6V using constant-on-time (COT) control, features ultra-low 17μA quiescent current, and includes EN, PG, and FB pins for sequencing and adjustable regulation. It targets space-constrained portable and embedded systems requiring compact, high-efficiency point-of-load conversion.

For engineers reviewing the MPM3805GQB-P datasheet, MPM3805GQB-P pinout, MPM3805GQB-P application, or MPM3805GQB-P equivalent, key selection criteria include its QFN-12 (2.5×3.0×0.9mm) package size, 0.47μH integrated inductor, 2800–4200kHz switching frequency, ±10% power-good window, and 100% duty-cycle dropout capability in low-VIN scenarios.

Technical Context

The MPM3805GQB-P implements a constant-on-time (COT) control architecture with input-voltage feedforward, enabling stable switching frequency across input and output voltage ranges while delivering fast transient response without external compensation. Its internal 0.47μH inductor and matched 110mΩ/70mΩ P/N-FETs are co-optimized for efficiency in both CCM and DCM operation.

It integrates cycle-by-cycle over-current protection with ≥1A current limit, thermal shutdown at 150°C (30°C hysteresis), hiccup-mode short-circuit recovery, and a dedicated open-drain PG pin with 550kΩ internal pull-up to VIN. The FB pin supports adjustable output via resistor divider; fixed-output variants omit FB functionality.

Key Specifications

Pinout & Package

MPM3805GQB-P uses a thermally enhanced QFN-12 package (2.5mm × 3.0mm × 0.9mm) with exposed thermal pad (pins 3–4 connected internally to SW node). The layout prioritizes low-inductance high-current paths: PGND (pins 1–2), OUT (pins 5–6), and VIN (pin 7) require direct, wide copper connections. AGND (pin 11) and OUT_S (pin 12) support precision sensing and noise isolation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TSM10501S and RT6220BGE, MPM3805GQB-P uniquely combines integrated inductor, PG/OUT_S/EN interfaces, 2.8–4.2MHz COT flexibility, and 17μA IQ in a 2.5×3.0mm footprint-making it optimal for miniaturized, sequenced, and battery-sensitive designs where component count and layout simplicity are decisive.

Availability

MPM3805GQB-P is available at Aetrix Electronics and suitable for portable instrumentation, SSD auxiliary power, and low-voltage FPGA I/O rails requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for MPM3805GQB-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 MPM3805 product line delivers fully integrated, surface-mount DC-DC modules targeting space-constrained, battery-powered, and thermally sensitive applications-emphasizing ease of use, minimal external components, and robust protection features.

FAQ

What is the function of the OUT_S pin on MPM3805GQB-P?

The OUT_S pin provides remote output voltage sensing to compensate for IR drop across PCB traces between the module's OUT pin and the actual load. It connects to the load-side of the output capacitor, enabling tighter load regulation (±0.5% typical) under varying current conditions-critical for precision analog or memory interface rails.

Can MPM3805GQB-P operate with input voltage equal to the output voltage?

Yes. MPM3805GQB-P supports 100% duty-cycle operation, allowing it to maintain regulation when VIN drops to VOUT (e.g., 3.0V input → 3.0V output). This dropout capability extends usable battery life in single-cell Li-ion systems where voltage declines from 4.2V to 3.0V during discharge.

How does the PG (Power Good) pin behave during startup and fault conditions?

PG is an open-drain output pulled up to VIN via an internal 550kΩ resistor. It asserts high when FB voltage remains within ±10% of 600mV for >50μs after soft-start completes. During UVLO, over-current, or thermal shutdown, PG is actively pulled low. No external pull-up is required.

What is the recommended input capacitor for MPM3805GQB-P at 5V input and 1.2V/0.6A output?

A 10μF X5R/X7R ceramic capacitor placed <1mm from VIN and PGND pins is recommended. For higher stability under dynamic load, add a 0.1μF NP0/C0G capacitor in parallel. Total RMS current rating should exceed 300mA, per the formula I_{CIN_RMS} ≈ I_LOAD × √(V_OUT/V_IN × (1 − V_OUT/V_IN)).

Does MPM3805GQB-P require external compensation components?

No. The constant-on-time (COT) control architecture is inherently stable and requires no external compensation network. Only the FB resistor divider (for adjustable versions), input capacitor, and output capacitor are needed-reducing design complexity and validation effort versus voltage-mode controllers.

What thermal considerations apply when mounting MPM3805GQB-P on a 2-layer PCB?

On a 2-layer board, use ≥2cm² of 1oz copper connected to the exposed thermal pad (pins 3–4) with ≥4 thermal vias (0.3mm diameter, filled or capped). Without this, junction temperature may exceed 125°C at 0.6A ambient >60°C. Thermal resistance rises from θ_JA = 65°C/W (4-layer) to ~95°C/W on 2-layer.

Is the MPM3805GQB-P pin-compatible with other MPM38xx variants?

Yes-MPM3805GQB-P shares identical QFN-12 (2.5×3.0mm) footprint and pinout with MPM3805GQB-12/-18/-25/-33. Only the FB pin is unused on fixed-output variants; all other pins (EN, PG, OUT_S, AGND, etc.) retain identical function and electrical behavior.