Monolithic Power Systems Inc. MPM3805GQB-33-P

Overview

MPM3805GQB-33-P from Monolithic Power Systems is a fixed-output 3.3V, 0.6A synchronous step-down DC-DC power module with integrated inductor and MOSFETs, operating from 2.5V–6V input. It uses Constant-On-Time (COT) control for fast transient response, delivers ±3% output accuracy at 10mA load, features 17μA quiescent current, and includes EN control and open-drain Power Good (PG) signaling - ideal for space-constrained portable I/O rails.

For engineers reviewing the MPM3805GQB-33-P datasheet, MPM3805GQB-33-P pinout, MPM3805GQB-33-P application, or MPM3805GQB-33-P equivalent, key selection criteria include its QFN-12 (2.5×3.0×0.9mm) footprint, 3.3V fixed output tolerance, thermal shutdown at 150°C, hiccup-mode short-circuit protection, and PG logic compatibility with 550kΩ internal pull-up to VIN.

Technical Context

The MPM3805GQB-33-P implements a monolithic synchronous buck architecture with integrated 0.47μH inductor and dual MOSFETs (110mΩ P-FET, 70mΩ N-FET), enabling full regulation without external magnetics. Its COT control loop uses input-voltage feedforward to maintain switching frequency between 2.8–4.2MHz across input and load conditions.

It supports 100% duty-cycle operation in dropout, employs zero-current detection for light-load DCM mode, and integrates dedicated analog ground (AGND), output sense (OUT_S), and thermal shutdown with 30°C hysteresis - all within a thermally enhanced QFN-12 package with exposed PGND pads.

Key Specifications

Pinout & Package

MPM3805GQB-33-P is housed in a thermally optimized QFN-12 package (2.5mm × 3.0mm × 0.9mm) with exposed PGND pads on the bottom for efficient heat dissipation. The package supports reflow soldering per JEDEC J-STD-020 and includes 12 terminals, five of which are functional pins; remaining pins serve thermal or internal test roles.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS826713 and LTM8003-3.3, the MPM3805GQB-33-P uniquely balances ultra-small footprint, remote sensing (OUT_S), and hiccup-mode fault recovery - making it optimal for portable 3.3V rails where layout density and robustness under intermittent shorts are critical.

Availability

MPM3805GQB-33-P is available at Aetrix Electronics and suitable for portable instrumentation, FPGA I/O power, SSD controller supplies, and space-constrained industrial sensors requiring stable component supply and rapid prototyping support.

Supply support for MPM3805GQB-33-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 series belongs to MPS's integrated power module product line, engineered specifically for compact, low-noise, high-efficiency DC-DC conversion in battery-powered and space-limited applications - emphasizing ease of use, minimal external components, and robust protection.

FAQ

What is the recommended input capacitor for MPM3805GQB-33-P?

A 10μF X5R/X7R ceramic capacitor placed within 1mm of VIN and PGND pins is recommended for most applications. For higher output voltages or noisy sources, a 22μF unit improves stability. An additional 0.1μF ceramic capacitor should be added in parallel if using bulk tantalum or electrolytic input caps to handle high-frequency ripple.

Does MPM3805GQB-33-P require external feedback resistors?

No. The "-33" suffix denotes a factory-trimmed fixed 3.3V output version; Pin 10 (FB) is internally connected and marked NC. External resistors are only required for the adjustable MPM3805GQB variant, which uses a 0.6V reference and external R1/R2 divider.

How does the Power Good (PG) pin function on this device?

PG is an open-drain output with a 550kΩ internal pull-up to VIN. It asserts high (Hi-Z state pulled to VIN) when the regulated output is within ±10% of 3.3V (i.e., 3.0–3.6V). If output deviates outside that window - due to overload, short, or UVLO - PG is actively pulled low by an internal MOSFET with <400Ω R_DS(on).

Can MPM3805GQB-33-P operate with 100% duty cycle?

Yes. The device supports 100% duty cycle operation, maintaining regulation even when input voltage drops to the output level (e.g., VIN = 3.3V). This ensures uninterrupted power delivery during battery discharge or input brown-out conditions without dropping out of regulation.

What thermal considerations apply to the QFN-12 package?

The QFN-12 exposes PGND pads on the bottom for thermal conduction. A minimum 40mm² copper pour connected to PGND via ≥4 thermal vias (0.3mm diameter) is required to achieve θ_JA ≈ 65°C/W. Without adequate copper, junction temperature may exceed 150°C at 0.6A load in still air, triggering thermal shutdown.

Is OUT_S pin mandatory for proper operation?

No, but strongly recommended for loads >5cm from the module. When connected to the load-side of the output trace, OUT_S enables remote sensing to compensate for IR drop in PCB traces, improving output regulation accuracy to ±1% under dynamic load. Leaving it unconnected defaults to local sensing at the OUT pins.

What protection features are built into MPM3805GQB-33-P?

It includes cycle-by-cycle over-current limiting (1.0A threshold), hiccup-mode short-circuit protection, thermal shutdown at 150°C with 30°C hysteresis, under-voltage lockout (2.3V rising threshold), and soft-start (1.5ms ramp). No external components are needed to activate these protections.