Monolithic Power Systems Inc. MPM3805GQB-Z

Overview

MPM3805GQB-Z from Monolithic Power Systems is a synchronous step-down DC-DC power module integrating MOSFETs and a 0.47μH inductor in a QFN-12 (2.5mm×3.0mm×0.9mm) package. It delivers up to 0.6A continuous output current from 2.5V–6V input, regulates output down to 0.6V (adjustable via FB pin), features constant-on-time (COT) control for fast transient response, and includes EN, PG, thermal shutdown, and hiccup-mode short-circuit protection. It is used in space-constrained portable instruments and FPGA core/I/O rail power.

For engineers reviewing the MPM3805GQB-Z datasheet, MPM3805GQB-Z pinout, MPM3805GQB-Z application, or MPM3805GQB-Z equivalent, key selection criteria include its integrated inductor simplifying layout, ultra-low 17μA quiescent current in active operation, 100% duty-cycle capability in dropout, ±10% power-good window with open-drain PG output, and requirement of only four external components (two capacitors + two FB resistors) for adjustable-output designs.

Technical Context

The MPM3805GQB-Z implements a constant-on-time (COT) control architecture with input-voltage feedforward, enabling stable 2.8–4.2MHz switching frequency across input and output voltage ranges. Its internal high-side PFET (110mΩ R_DS(ON)) and low-side NFET (70mΩ) are co-optimized with the integrated 0.47μH inductor (125mΩ DCR) to support CCM/DCM transition at light load.

It integrates analog ground (AGND) and output sense (OUT_S) pins for precision regulation, employs a 0.6V internal reference with 588–612mV feedback voltage tolerance, and uses cycle-by-cycle current limiting (≥1A threshold) combined with thermal shutdown (150°C trip, 30°C hysteresis) for robust fault handling.

Key Specifications

Pinout & Package

MPM3805GQB-Z is housed in a thermally enhanced QFN-12 package (2.5mm × 3.0mm × 0.9mm) with exposed thermal pad (pins 3–4 connected internally to SW node and tied to copper pour for heat dissipation). The package supports reflow soldering per JEDEC J-STD-020 and achieves θ_JA = 65°C/W on a 4-layer PCB.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS82671 and LTM8003, the MPM3805GQB-Z uniquely balances ultra-compact height (0.9mm), full 0.6–6V input adaptability, adjustable output via FB, and integrated PG/EN logic-making it optimal for portable, battery-fed, space-limited designs requiring flexible rail generation.

Availability

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

Supply support for MPM3805GQB-Z 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 MPM3805 product line delivers fully integrated, easy-to-use DC-DC modules targeting space- and efficiency-critical portable, computing, and storage systems where minimal external components and guaranteed thermal performance are essential.

FAQ

What output voltage options does MPM3805GQB-Z support?

The MPM3805GQB-Z is the adjustable version, supporting any output from 0.6V to ≤VIN via an external resistor divider on the FB pin. Fixed-output variants (e.g., MPM3805GQB-12, -18) are separate part numbers with factory-trimmed 1.2V, 1.8V, 2.5V, or 3.3V outputs. The GQB-Z itself has no internal voltage reference other than the 0.6V FB threshold.

Can MPM3805GQB-Z operate with input voltage equal to output voltage?

Yes. The device supports 100% duty-cycle operation, allowing it to maintain regulation when VIN drops to within ~100mV above VOUT (e.g., 1.3V input for 1.2V output). This dropout behavior is enabled by the synchronous rectifier and COT control architecture, not a separate LDO mode.

How is thermal performance validated for this module?

Thermal resistance is characterized per JESD51-7 on a 4-layer PCB: θ_JA = 65°C/W and θ_JC = 13°C/W. The exposed SW pad (pins 3–4) must be soldered to ≥100mm² of 2oz copper with ≥4 thermal vias to achieve rated 0.6A output at +85°C ambient. Derating curves in the datasheet confirm 0.6A is sustainable up to +125°C junction temperature.

Does the PG pin require an external pull-up resistor?

No. The PG pin has an internal 550kΩ pull-up resistor to VIN, so no external component is needed. It operates as an open-drain indicator: pulled high when FB voltage is within ±10% of 0.6V, and actively driven low otherwise. Load capacitance should remain below 100pF to meet the 50μs delay specification.

What is the minimum recommended output capacitor value?

A minimum of 20μF ceramic (X5R/X7R) is recommended for stable operation at full 0.6A load. The datasheet specifies 20μF in typical performance plots and confirms <15mV peak-to-peak ripple at 2.5V/0.6A with 20μF + low-ESR design. Using <10μF risks instability and excessive output voltage deviation under transient load.

Is OUT_S pin mandatory for all designs?

No. OUT_S is optional for remote sensing to improve load regulation accuracy. If omitted, the device regulates at the OUT pin. For layouts where trace resistance between OUT and load exceeds 10mΩ (e.g., >2cm length), connecting OUT_S directly to the load improves regulation error from ±2% to ±0.5% under full load.

How does light-load efficiency compare to standard PWM controllers?

MPM3805GQB-Z uses a proprietary discontinuous conduction mode (DCM) scheme that disables the low-side FET when inductor current reverses, reducing switching and conduction losses. At 1mA load and 3.3V output, it achieves >75% efficiency-~20 percentage points higher than fixed-frequency PWM equivalents with similar integration level.