Monolithic Power Systems Inc. MPM3805GQB-12-Z

Overview

MPM3805GQB-12-Z from Monolithic Power Systems is a fixed-output 1.2V, 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 - deployed in space-constrained portable instruments and SSD power rails.

For engineers reviewing the MPM3805GQB-12-Z datasheet, MPM3805GQB-12-Z pinout, MPM3805GQB-12-Z application, or MPM3805GQB-12-Z equivalent, key selection criteria include its QFN-12 (2.5×3.0×0.9mm) package size, 100% duty-cycle dropout capability, hiccup-mode short-circuit protection, thermal shutdown at 150°C, and minimal external component count (only input/output capacitors required for fixed-output operation).

Technical Context

The MPM3805GQB-12-Z implements a COT control architecture with input-voltage feedforward to maintain stable 2.8–4.2MHz switching frequency across input and output conditions. Its internal 0.47μH inductor and matched 110mΩ/70mΩ PCH/NCH MOSFETs enable high-efficiency regulation without external magnetics.

It integrates analog ground (AGND) separation, OUT_S sense pin for remote voltage sensing, and a dedicated PG pin with 550kΩ internal pull-up to VIN and ±10% regulation window detection. The EN pin features 1.2V logic-high threshold and internal 1MΩ pulldown resistor for default-disable behavior.

Key Specifications

Pinout & Package

MPM3805GQB-12-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 4-layer PCB.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TSM105012 and RT6220B-12GJ6F, MPM3805GQB-12-Z uniquely combines PG + EN + OUT_S in a 0.9mm-height module, enabling robust power sequencing, precise remote sensing, and thermal-safe operation - critical for industrial portable instruments and high-reliability storage designs.

Availability

MPM3805GQB-12-Z is available at Aetrix Electronics and suitable for portable instrumentation, SSD power delivery, and low-voltage I/O systems requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for MPM3805GQB-12-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 power ICs, with design centers in the US, China, and Taiwan, and global manufacturing partnerships.

The MPM3805 product line delivers fully integrated, ultra-compact DC-DC modules targeting space- and efficiency-constrained applications in portable electronics, storage, and industrial instrumentation - emphasizing ease of use, minimal external components, and robust protection features.

FAQ

What is the recommended input capacitor for MPM3805GQB-12-Z?

A 10μF X5R/X7R ceramic capacitor placed within 2mm of VIN and PGND pins is recommended. For systems with >0.4A load steps or input sources exceeding 100mΩ impedance, add a 0.1μF NP0 ceramic in parallel to suppress high-frequency ringing. Total RMS current rating must exceed 300mA per the datasheet's I_CIN(RMS) = I_LOAD × √(V_OUT/V_IN × (1 − V_OUT/V_IN)) formula.

Does MPM3805GQB-12-Z require external feedback resistors?

No. The -12 suffix denotes a factory-trimmed fixed 1.2V output; pin 10 (FB) is internally connected and must remain unconnected. Only input and output capacitors are required - no resistor divider, unlike the adjustable MPM3805GQB version which uses pins 10 and 11 for feedback.

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

PG remains low until V_FB reaches 0.54V (−10% of 0.6V reference); it then pulls high to VIN via internal 550kΩ resistor. If V_FB drops below 0.54V or exceeds 0.66V (e.g., due to overload, short, or capacitor failure), PG is actively pulled low within 50μs. PG deasserts before soft-start completes if output fails to regulate.

Can MPM3805GQB-12-Z operate with VIN = 1.8V?

No. Absolute maximum ratings specify minimum VIN = 2.5V for normal operation. At 1.8V, UVLO (2.15–2.48V threshold) prevents startup, and internal bias circuits cannot sustain regulation. For sub-2.5V inputs, consider charge-pump or boost-buck architectures - MPM3805GQB-12-Z is not rated for dropout below 2.5V.

What is the thermal pad connection requirement for QFN-12 package?

Pins 3 and 4 are internal SW-node thermal pads and must be soldered to a minimum 25mm² copper pour connected to PGND. Thermal vias (≥4×0.3mm diameter) should be placed under the pad to inner ground layers. Failure to thermally anchor the pad results in junction temperature exceeding 150°C at >0.4A load, triggering thermal shutdown.

Is OUT_S pin mandatory for stable operation?

No - OUT_S is optional. When unused, tie OUT_S to OUT. Using OUT_S improves load regulation error from ±3% to ±0.5% under 0–0.6A steps by compensating for PCB trace resistance (typically 20–50mΩ). For non-critical applications like LED bias or sensor analog supplies, omitting OUT_S routing simplifies layout without instability.

What happens during short-circuit events?

Upon current limit detection (>1A peak), the device enters hiccup mode: disables switching, discharges soft-start capacitor, waits ~50ms, then attempts soft-start again. This repeats until short is removed. During hiccup, PG is held low and quiescent current drops to 1μA, minimizing stress on input source and PCB traces.