Monolithic Power Systems Inc. MP3418GJ-Z

Overview

MP3418GJ-Z from Monolithic Power Systems is a synchronous, current-mode step-up DC-DC converter with true output disconnect, designed for ultra-low-voltage battery-powered systems. It starts up from 0.8V input, delivers up to 400mA output current at 1.2MHz fixed switching frequency, and regulates output voltages from 1.8V to 4.0V using an external resistive divider on the FB pin-enabling compact power rails in portable medical devices and wireless peripherals.

For engineers reviewing the MP3418GJ-Z datasheet, MP3418GJ-Z pinout, MP3418GJ-Z application, or MP3418GJ-Z equivalent, key selection criteria include its 0.1µA shutdown current, integrated P/N-MOSFET synchronous rectifier, VIN>VOUT down-mode operation, and TSOT23-8 package constraints for high-density PCB layouts.

Technical Context

The MP3418GJ-Z implements fixed-frequency (1.2MHz) peak-current-mode control with internal slope compensation and soft-start, enabling stable regulation across 0.6V–4V input and 1.8V–4V output ranges. Its dual-MOSFET architecture includes a 110mΩ NMOS switch and a 120mΩ PMOS disconnect switch, with body-diode conduction eliminated to ensure true output isolation during shutdown.

Startup behavior includes three distinct phases: linear charge (PMOS on, 200mA-limited), free-running mode (500kHz, 400mA-limited), and closed-loop boost/down operation. Over-voltage protection triggers at ~1.23V FB threshold, while thermal shutdown activates at 150°C with 20°C hysteresis-both guaranteed by design.

Key Specifications

Pinout & Package

MP3418GJ-Z is housed in a thermally enhanced 8-pin TSOT23 package (2.9mm × 1.6mm × 0.85mm), with exposed pad for improved heat dissipation (θJA = 100°C/W on 4-layer board). Pin 5 (NC) must remain unconnected; AGND (Pin 6) and PGND (Pin 4) require separate low-impedance ground routing to minimize noise coupling into the error amplifier.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-up converter applications.

Compared with TPS61291DRVR and ADP5070ACPZ-R7, MP3418GJ-Z uniquely combines sub-1V start-up, true output disconnect, and VIN>VOUT down-mode in a TSOT23-8 package-making it the sole option for space-constrained, single-cell battery systems requiring zero standby drain and seamless voltage transition during charging.

Availability

MP3418GJ-Z is available at Aetrix Electronics and suitable for portable medical devices, wireless peripherals, handheld scanners, and low-power IoT edge nodes requiring stable component supply with guaranteed long-term availability and RoHS-compliant packaging.

Supply support for MP3418GJ-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 manufacturing partners qualified to AEC-Q200 and ISO 9001 standards.

The MP34xx series targets ultra-low-voltage, high-efficiency DC-DC conversion for battery-powered wearables and medical devices-emphasizing minimal quiescent current, true output isolation, and compact integration to replace discrete boost solutions.

FAQ

What is the minimum input voltage required to initiate startup?

The MP3418GJ-Z guarantees startup at 0.8V (typical 1.0V) with no load, enabling operation as single-cell alkaline or NiMH batteries discharge below 1.0V. Startup current is internally limited to ~200mA during linear charge phase to prevent input voltage collapse.

How does the device achieve true output disconnect during shutdown?

During shutdown, the internal PMOS switch is fully turned off and its body diode is structurally eliminated-preventing any forward conduction path from OUT to IN. This allows the output capacitor to fully discharge and reduces input current to 0.1µA typical, with no external components required.

Can MP3418GJ-Z regulate when input voltage exceeds output voltage?

Yes. When VIN > VOUT + 200mV, the device enters down-mode operation: the NMOS is disabled, and the PMOS gate is driven to connect VIN directly to OUT. Regulation continues, though efficiency drops due to PMOS conduction loss-output current must be limited to maintain safe junction temperature.

What are the critical PCB layout requirements for stable operation?

Place the output capacitor directly between OUT (Pin 2) and PGND (Pin 4) with no vias; route the inductor from SW (Pin 3) with shortest possible trace; isolate AGND (Pin 6) from PGND except at one star point; and locate FB divider resistors adjacent to AGND to minimize noise coupling into the error amplifier.

Does the device include over-voltage and short-circuit protection?

Yes. Over-voltage protection triggers when FB exceeds 1.23V (corresponding to ~4.0V at VOUT with standard divider), clamping output. Short-circuit protection combines 400mA peak switch current limiting, thermal shutdown at 150°C, and automatic re-attempt via linear charge phase-allowing sustained short-circuit tolerance without damage.

What is the recommended inductor value and why?

A 6.8µH shielded ferrite inductor is recommended: it balances size, ripple current (~35% of 400mA), and PSM threshold. Values from 4.7µH to 10µH are acceptable; larger inductors reduce ripple but raise PSM entry point and physical size, while smaller values increase EMI and may trigger premature current limiting.