Monolithic Power Systems Inc. MP3421GG-Z

Overview

MP3421GG-Z from Monolithic Power Systems is a synchronous step-up DC-DC converter with true output disconnect, designed for low-input-voltage battery-powered systems. It operates from 1.9V to 5.5V input, delivers up to 5.5A switch current, supports 2.5V–5.5V adjustable output, and integrates P-channel NMOS/PMOS power switches in a 2mm×2mm QFN-14 package - enabling compact 5V/2.1A power banks and USB supply rails.

For engineers reviewing the MP3421GG-Z datasheet, MP3421GG-Z pinout, MP3421GG-Z application, or MP3421GG-Z equivalent, key selection criteria include its 600kHz fixed-frequency current-mode control, 43µA quiescent current at no load, true output disconnect during shutdown, integrated soft-start and compensation, and comprehensive protection suite (OCP/SCP/OVP/OTP).

Technical Context

The MP3421GG-Z implements fixed-frequency (600kHz) current-mode PWM control with internal slope compensation and an error amplifier referenced to 0.807V. Its startup sequence includes linear charge mode (0.2A–0.7A programmable limit) until VOUT reaches 1.7V, then transitions to closed-loop boost operation with >5.5A peak switch-current capability.

True output disconnect is achieved via controlled PMOS gate drive that eliminates body diode conduction between OUT and IN; EN logic directly disables switching and isolates load. Bias sourcing automatically shifts from IN to OUT once VOUT exceeds VIN, enabling efficient high-side regulation without external bias circuitry.

Key Specifications

Pinout & Package

MP3421GG-Z is housed in a thermally enhanced 14-pin QFN package (2mm × 2mm, 0.5mm pitch) with exposed thermal pad (PGND-connected). The package supports high-power density designs and requires proper PCB copper pour and vias for thermal management.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS61088RHLR and RT9086AGQW, MP3421GG-Z uniquely balances 1.9V start-up, true PMOS-based output disconnect, and 5.5A current headroom in a 2mm×2mm footprint - making it optimal for space-constrained, battery-isolation-sensitive USB power banks and portable chargers.

Availability

MP3421GG-Z is available at Aetrix Electronics and suitable for power banks, USB power adapters, wireless charging cases, and IoT sensor nodes requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP3421GG-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 across Asia and North America.

The MP3421 belongs to MPS's high-efficiency DC-DC boost converter product line, engineered specifically for portable battery-powered applications demanding ultra-low quiescent current, true output disconnect, and minimal external component count.

FAQ

What input voltage range does MP3421GG-Z support, and how does it handle deep discharge?

The MP3421GG-Z operates from 1.9V to 5.5V input, enabling reliable startup even from deeply discharged single-cell Li-ion batteries (down to ~2.0V). Its 1.3V UVLO rising threshold and linear charge mode with 0.2A–0.7A inrush limiting ensure controlled ramp-up without damaging the input source or output capacitor.

How does true output disconnect work, and what design benefits does it provide?

True output disconnect is implemented via an internal P-channel MOSFET that fully isolates the OUT pin from IN when EN is low - eliminating body diode conduction and reverse current. This prevents battery drain during standby, enables external bias retention on VOUT, and removes the need for an external blocking diode in most applications.

Can MP3421GG-Z regulate output voltages other than 5V, and how is adjustment performed?

Yes - MP3421GG-Z supports 2.5V to 5.5V output via an external resistor divider on the FB pin. Using VOUT = 0.807V × (1 + R1/R2), designers select R1 and R2 to set the target voltage; R1 ≥ 600kΩ is recommended for stability and low quiescent current, with X5R/X7R ceramic capacitors used for filtering.

What protection features are integrated, and how do they respond to faults?

MP3421GG-Z integrates over-current (OCP), short-circuit (SCP), over-voltage (OVP at 7V), over-temperature (OTP at 150°C), and input UVLO protection. On fault detection, it shuts down immediately and auto-restarts after 40µs (for OCP/SCP) or resumes operation once temperature drops below 130°C (for OTP), ensuring robust field reliability.

Is external compensation required, and what is the typical external component count?

No external compensation is required - the MP3421GG-Z features fully internal loop compensation. A typical application uses only five external components: one 1–2.2µH inductor, one ≥22µF input capacitor, one ≥22µF output capacitor, and two resistors for FB voltage setting - minimizing BOM cost and board area.

What thermal performance can be expected in the 2mm×2mm QFN package?

In a standard 4-layer PCB with 2-in² 2oz copper pour and 6 thermal vias under the exposed pad, the MP3421GG-Z achieves θJA = 80°C/W. At 2.1A/5V output from 2.8V input, junction temperature rise is typically <45°C above ambient - well within the 125°C max operating range and enabling fanless operation.