Monolithic Power Systems Inc. MPM3805GQB-18-P

Overview

MPM3805GQB-18-P from Monolithic Power Systems is a synchronous step-down DC-DC power module with integrated inductor, delivering 1.8 V fixed output at up to 0.6 A from 2.5–6 V input. It uses Constant-On-Time (COT) control for fast transient response, features ultra-low 17 μA quiescent current, and includes power-good (PG) and enable (EN) pins for sequencing in space-constrained portable systems.

For engineers reviewing the MPM3805GQB-18-P datasheet, MPM3805GQB-18-P pinout, MPM3805GQB-18-P application, or MPM3805GQB-18-P equivalent, key selection criteria include its QFN-12 (2.5×3.0×0.9 mm) package, 1.8 V ±1.5% output accuracy at 10 mA, 100% duty-cycle operation in dropout, hiccup-mode short-circuit protection, and thermal shutdown at 150°C.

Technical Context

The MPM3805GQB-18-P integrates a 0.47 μH inductor, 110 mΩ high-side PFET, and 70 mΩ low-side NFET into a monolithic QFN-12 module. Its COT architecture uses input-voltage feedforward to maintain switching frequency between 2.8–4.2 MHz across input and load conditions, eliminating loop compensation components.

It implements light-load DCM via zero-current detection, enforces cycle-by-cycle overcurrent limiting at ≥1.0 A, and provides precise power sequencing via open-drain PG (±10% trip, 50 μs delay) and logic-controlled EN (1.2 V high threshold). Thermal hysteresis is 30°C after shutdown at 150°C.

Key Specifications

Pinout & Package

MPM3805GQB-18-P is housed in a thermally enhanced QFN-12 package measuring 2.5 mm × 3.0 mm × 0.9 mm, with exposed thermal pad (pins 3–4) connected to internal SW node for PCB heat sinking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS82084 and LTM8003-1.8, MPM3805GQB-18-P uniquely supports 2.5 V start-up, includes OUT_S for precision regulation in compact layouts, and delivers identical 0.6 A capability in the smallest footprint (2.5×3.0 mm).

Availability

MPM3805GQB-18-P is available at Aetrix Electronics and suitable for portable instrumentation, SSD power management, and FPGA I/O rail applications requiring stable component supply, consistent parametric performance, and long-term production continuity.

Supply support for MPM3805GQB-18-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.

The MPM3805 product line delivers fully integrated, easy-to-use DC-DC modules targeting space- and efficiency-critical portable, storage, and embedded applications-emphasizing minimal external components and rapid time-to-market.

FAQ

What is the recommended input capacitor for MPM3805GQB-18-P?

A 10 µF X5R/X7R ceramic capacitor placed directly between VIN and PGND is recommended. For higher output voltages or noisy sources, a 22 µF unit improves stability. A 0.1 µF ceramic should be added in parallel if using bulk tantalum or electrolytic input caps.

Does MPM3805GQB-18-P require external feedback resistors?

No. As a fixed-output variant, the FB pin is internally connected to the 0.6 V reference. External resistors are unnecessary-only input and output capacitors are required for basic operation.

How does the OUT_S pin improve regulation accuracy?

OUT_S enables remote voltage sensing at the load, compensating for IR drop across PCB traces. When connected to the load side of the output net, it improves load regulation to ±1% over full current range, critical for sensitive digital I/O rails.

Can MPM3805GQB-18-P operate with input voltage equal to output voltage?

Yes. Its 100% duty-cycle capability allows continuous regulation down to VIN = VOUT (1.8 V), making it suitable for battery-powered systems operating through full discharge cycles without brownout.

What thermal derating applies above 25°C ambient?

With θJA = 65°C/W on a 4-layer PCB, maximum continuous power dissipation drops linearly: PD(MAX) = (150°C − TA)/65. At 85°C ambient, max dissipation falls to ~1.0 W, limiting practical output current to ~0.5 A depending on layout and airflow.

Is the PG pin compatible with 1.8 V logic systems?

Yes. PG is open-drain with internal 550 kΩ pull-up to VIN. When VIN ≥ 2.5 V, PG pulls up to VIN (not 1.8 V), so an external 1.8 V-compatible level shifter or pull-down resistor is needed to interface with 1.8 V GPIO.

What happens during short-circuit events?

Upon overcurrent detection, the device enters hiccup mode: it disables the power stage, discharges the soft-start capacitor, waits ~10 ms, then attempts restart. This repeats until fault clears, preventing thermal damage while maintaining automatic recovery.