Monolithic Power Systems Inc. MP3209DJ-LF-P

Overview

MP3209DJ-LF-P from Monolithic Power Systems is a current-mode 1.4MHz boost converter with integrated 0.5Ω MOSFET, supporting 2.5V–6V input and up to 22V output at 350mA peak switch current. It features internal soft-start, UVLO (2.45V rising), thermal shutdown (160°C), and operates in ultra-thin TSOT23-5 package for space-constrained portable power rails.

For engineers reviewing the MP3209DJ-LF-P datasheet, MP3209DJ-LF-P pinout, MP3209DJ-LF-P application, or MP3209DJ-LF-P equivalent, key selection criteria include fixed 1.4MHz switching frequency, 1.25V feedback reference, 85% max duty cycle, and compatibility with low-profile 22µH inductors and ceramic capacitors in sub-1mm height designs.

Technical Context

The MP3209DJ-LF-P implements a fixed-frequency peak-current-mode control architecture with built-in slope compensation to prevent subharmonic oscillation above 50% duty cycle. Its error amplifier compares FB voltage against a 1.25V bandgap reference and drives PWM logic via a stabilized ramp signal.

Operation relies on internal MOSFET switching between GND and up to 22V at SW pin, with EN pin enabling/disabling regulation via 1.3V threshold and 100mV hysteresis. Soft-start ramps current limit over 120µs to limit inrush and output overshoot during startup.

Key Specifications

Pinout & Package

MP3209DJ-LF-P uses the TSOT23-5 package (1.6 mm × 2.9 mm × 1.1 mm), optimized for high-density portable layouts with exposed pad not present in this variant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar boost converter applications.

Compared with TPS610992DRCR and RT9013-33GB, MP3209DJ-LF-P uniquely delivers 22 V output capability in a 1.1 mm height TSOT23-5 package with integrated MOSFET-making it irreplaceable for compact high-voltage boost needs where alternatives either lack voltage range or misrepresent topology.

Availability

MP3209DJ-LF-P is available at Aetrix Electronics and suitable for cell phones, OLED drivers, and external modems requiring stable component supply with RoHS-compliant, lead-free packaging and guaranteed TSOT23-5 form factor.

Supply support for MP3209DJ-LF-P 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 distribution since 1997.

The MP3209 belongs to MPS's low-power DC-DC converter product line, engineered specifically for space- and height-constrained portable electronics needing efficient, integrated boost conversion from single-cell sources.

FAQ

What is the maximum achievable output voltage with MP3209DJ-LF-P?

The MP3209DJ-LF-P supports output voltages up to 22 V, as confirmed by absolute maximum rating for SW pin (–0.3 V to 25 V) and operating condition specification (VOUT = 3 V to 22 V). This is achieved using an external resistor divider on FB pin with 1.25 V reference; no internal clamp limits regulation beyond this value.

Does MP3209DJ-LF-P require external compensation components?

No. The MP3209DJ-LF-P is internally compensated, as explicitly stated in the FEATURES section and verified in the APPLICATIONS INFORMATION section. Only the FB resistor divider, input capacitor (≥4.7 µF), output capacitor (4.7–10 µF), inductor (e.g., 22 µH), and optional feed-forward RC network are required for stable operation.

Can MP3209DJ-LF-P operate with a 2.5 V input and deliver 12 V output?

Yes. The datasheet specifies 2.5 V minimum input and 22 V maximum output, and typical application circuits (Figure 2) demonstrate 5 V → 12 V conversion. At 2.5 V input, the required duty cycle is ~79%, within the 85% maximum duty cycle limit, and efficiency remains viable (>75%) per characteristic curves at light-to-moderate loads.

What is the purpose of the NC pins in the TSOT23-5 package?

The TSOT23-5 package has no NC pins; all five pins are functional (SW, GND, FB, EN, IN). The NC designation appears only in the 8-pin UTQFN variant (pins 3 and 7). For MP3209DJ-LF-P, every pin serves a defined electrical role-no unused terminals exist in this configuration.

How does the internal soft-start sequence affect startup behavior?

The internal soft-start ramps the current limit in three equal steps every 40 µs, reaching full 350 mA limit after 120 µs. This controls inrush current into output capacitance, limiting input surge and suppressing output voltage overshoot-critical for protecting downstream OLED panels or LED strings during power-up.

Is thermal performance adequate in the TSOT23-5 package at full load?

At TA = +25°C, the TSOT23-5 package has θJA = 220°C/W and PD(MAX) = 0.57 W. Under worst-case 5 V → 12 V/350 mA operation (~70% efficiency), dissipation is ~1.2 W-exceeding safe continuous operation. Derating or PCB copper pour is required; the 2x2 QFN variant is recommended for sustained >200 mA loads.