Monolithic Power Systems Inc. MP3221GJ-Z

Overview

MP3221GJ-Z from Monolithic Power Systems is a 1.2MHz, current-mode step-up DC-DC converter with integrated 88mΩ MOSFET, 2.7A switch current limit, and true input-output disconnect via FAULT-driven external PMOS. It operates from 2.5V–6V input to deliver up to 5V/1A output, supporting single-cell Li-ion or triple-cell alkaline/NiMH battery systems in portable media players and wireless peripherals.

For engineers reviewing the MP3221GJ-Z datasheet, MP3221GJ-Z pinout, MP3221GJ-Z application, or MP3221GJ-Z equivalent, key selection criteria include its 270µA quiescent current, internal soft-start and compensation, 1.2MHz fixed-frequency operation, and fault-activated input disconnect capability for <1µA shutdown current.

Technical Context

The MP3221GJ-Z implements a constant-frequency peak-current-mode boost architecture with built-in slope compensation to prevent subharmonic oscillation above 50% duty cycle. Its error amplifier compares 0.796V FB reference against resistor-divider feedback to regulate output voltage dynamically.

Startup sequencing is controlled by the FAULT pin, which ramps the external PMOS gate slowly until VIN − 1.8V is reached before enabling switching; short-circuit protection triggers FAULT pull-up when FB drops to 150mV post-startup, forcing PMOS turn-off and full VOUT–VIN isolation.

Key Specifications

Pinout & Package

The MP3221GJ-Z is housed in a 6-pin TSOT23-6 package (2.9 mm × 1.6 mm × 0.85 mm), optimized for space-constrained portable applications. Pin functions are validated per MPS datasheet Rev. 1.0 (2013).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS61099YFFR and RT9086AGQW, the MP3221GJ-Z uniquely integrates a FAULT pin with defined timing and drive strength to directly control external PMOS for guaranteed input-output isolation - critical for battery-powered systems requiring zero-backdrive and fail-safe shutdown.

Availability

MP3221GJ-Z is available at Aetrix Electronics and suitable for portable media players, wireless peripherals, and smartphone accessories requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP3221GJ-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, motor drive, and automotive applications.

The MP3221 belongs to MPS's high-efficiency DC-DC boost converter product line, designed specifically for battery-powered portable electronics needing compact size, low IQ, and reliable input-output isolation.

FAQ

What is the minimum recommended output capacitance for stable operation?

The MP3221GJ-Z requires a minimum 22 µF ceramic output capacitor rated at the programmed output voltage. Lower ESR types like X5R or X7R are recommended to ensure loop stability and minimize ripple. Larger values improve transient response and reduce peak-to-peak output voltage deviation under dynamic load steps.

How does the FAULT pin behave during startup and fault conditions?

At startup, the FAULT pin ramps the external PMOS gate slowly until VIN − 1.8 V is reached, then enables switching. During output short-circuit, FB voltage drops to ≤150 mV, causing FAULT to pull high and turn off the PMOS within microseconds-fully isolating VIN from VOUT. This behavior is confirmed in the functional block diagram and protection section of the datasheet.

Can the MP3221GJ-Z operate without an external PMOS?

Yes - the MP3221GJ-Z functions as a standard boost converter without external PMOS. However, the true input-output disconnect feature (including <0.15 µA shutdown current and short-circuit isolation) is only enabled when a properly selected PMOS is connected to the FAULT pin per the application guidelines.

What is the maximum duty cycle limitation and how does it affect output voltage?

The MP3221GJ-Z has a maximum duty cycle of 90%, limiting the theoretical boost ratio. With a 2.5 V minimum input, this supports up to ~25 V output in ideal conditions, though practical limits (switch resistance, inductor saturation, thermal constraints) restrict usable VOUT to ≤6 V as specified in the absolute maximum ratings and typical application circuits.

Is the 0.796 V FB reference voltage production-tested or characterized?

The 0.796 V FB reference is specified as typical with ±1.5% tolerance over temperature and line/load conditions. While the datasheet notes that some parameters (e.g., thermal shutdown thresholds) are engineering-characterized, the FB voltage is explicitly listed in the Electrical Characteristics table with min/typ/max values and tested across production lots per MPS quality assurance protocols.

Does the MP3221GJ-Z support adjustable switching frequency?

No - the MP3221GJ-Z uses a fixed 1.2 MHz internal oscillator. Frequency cannot be adjusted via external components or pins. This simplifies design and ensures consistent EMI profile and inductor sizing, as validated in the typical application circuits and performance curves.

What thermal derating applies in a 4-layer PCB layout?

On a JEDEC-standard 4-layer PCB, the MP3221GJ-Z has θJA = 220°C/W. At TA = 25°C, maximum continuous power dissipation is calculated as (150°C − 25°C)/220°C/W ≈ 0.567 W. Exceeding this causes thermal shutdown activation at 150°C junction temperature, with 20°C hysteresis ensuring safe cooldown before restart.