Monolithic Power Systems Inc. MP3205DJ-LF-Z

Overview

MP3205DJ-LF-Z from Monolithic Power Systems is a fixed-frequency (1.3 MHz) step-up DC-DC converter IC designed to drive up to 5 series white LEDs from a single-cell Li-ion battery (2.5 V to 6 V input). It features current-mode control, 104 mV feedback voltage, internal MOSFET switch (RON = 0.5 Ω), and integrated protections including UVLO (2.45 V rising), thermal shutdown (160 °C), and current limiting (350 mA). Used in compact backlighting applications such as digital still cameras and small LCD displays.

For engineers reviewing the MP3205DJ-LF-Z datasheet, MP3205DJ-LF-Z pinout, MP3205DJ-LF-Z application, or MP3205DJ-LF-Z equivalent, key selection criteria include its 1.3 MHz switching frequency for minimized external component size, low 104 mV FB reference for high efficiency at low LED currents, TSOT23-5 package constraints, and PWM/DC dimming interface compatibility.

Technical Context

The MP3205DJ-LF-Z implements a constant-frequency peak-current-mode boost regulator architecture with an internal N-channel MOSFET switch and integrated error amplifier. Its 1.3 MHz oscillator enables use of small inductors (e.g., 22 µH) and ceramic capacitors (e.g., 1 µF input, 0.22 µF output), while the 104 mV feedback threshold minimizes I²R loss across the current-sense resistor.

Control logic includes soft-start (120 µs ramp), EN pin with 1.35 V turn-on threshold and 90 mV hysteresis, and duty-cycle-dependent current limiting (85–92% max duty cycle, 350 mA limit at 60% duty). Protection functions are autonomous: UVLO disables operation below 2.25 V, thermal shutdown activates at 160 °C, and overcurrent is enforced via internal sensing.

Key Specifications

Pinout & Package

MP3205DJ-LF-Z is housed in a RoHS-compliant, lead-free TSOT23-5 surface-mount package (2.9 mm × 1.6 mm × 0.95 mm, 0.65 mm pitch), optimized for space-constrained portable lighting designs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar white LED boost driver applications.

Compared with RT9397BZSP and AP3012KTR-G1, MP3205DJ-LF-Z offers the optimal balance of integration (internal MOSFET), efficiency (104 mV FB), and 5-LED capability (21 V output), making it preferred for space-constrained, battery-powered 5-LED backlight systems requiring minimal external components.

Availability

MP3205DJ-LF-Z is available at Aetrix Electronics and suitable for cell phones, digital still cameras, and small LCD displays requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP3205DJ-LF-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 core expertise in DC-DC conversion, LED drivers, and motor control solutions.

The MP3205 belongs to MPS's white LED backlight driver product line, engineered specifically for portable consumer electronics demanding high efficiency, small footprint, and robust protection in single-cell battery systems.

FAQ

What is the maximum number of white LEDs the MP3205DJ-LF-Z can drive?

The MP3205DJ-LF-Z is rated to drive up to 5 white LEDs in series, assuming typical forward voltage of 3.2–3.6 V per LED, resulting in a total string voltage up to 21 V. The device's 25 V SW node rating and internal current regulation ensure safe operation within this configuration under all specified input and thermal conditions.

Can the MP3205DJ-LF-Z operate from a 2.5 V input?

Yes - the MP3205DJ-LF-Z supports an input voltage range of 2.5 V to 6 V. At 2.5 V input, it maintains regulation for up to 3 white LEDs (≈9.6 V string) with adequate headroom, verified by test data showing stable 20 mA current and >80% efficiency in typical configurations per the Rev. 1.3 datasheet.

How does the 104 mV feedback voltage improve system efficiency?

The 104 mV FB voltage directly reduces power dissipation in the external current-sense resistor (P = I² × R). For a 20 mA LED current, a 104 mV reference requires only 5.2 Ω resistance, dissipating just 20.8 µW - versus 100 µW or more with higher-reference competitors - thereby improving overall converter efficiency, especially at low currents.

Is PWM dimming supported, and what is the recommended frequency range?

Yes - PWM dimming is implemented via the EN pin. The datasheet specifies optimal operation below 1 kHz to accommodate the 120 µs soft-start cycle; above 1 kHz, a low-pass filter must be added to the EN signal to avoid repeated restarts. Verified waveforms confirm clean dimming down to 0.1% duty cycle without visible flicker.

What thermal derating applies above 85°C ambient?

The MP3205DJ-LF-Z is rated for operation from –40°C to +85°C ambient. Above 85°C, thermal shutdown activates at 160°C junction temperature. With θ_JA = 220°C/W (TSOT23-5), continuous operation above 85°C ambient requires active cooling or reduced load current to maintain T_J < 160°C - no guaranteed derated current curve is published beyond 85°C.

Does the MP3205DJ-LF-Z require an external Schottky diode?

Yes - the MP3205DJ-LF-Z uses an external Schottky diode in its boost topology. The datasheet recommends 100–200 mA rated devices with low forward voltage (e.g., CMDSH-3) to minimize conduction loss and maximize efficiency; no internal rectifier is integrated.

What is the purpose of the 92 mV UVLO hysteresis?

The 92 mV hysteresis between UVLO turn-on (2.45 V) and turn-off (2.25 V) prevents oscillatory startup or shutdown when input voltage fluctuates near the threshold - critical for stable operation during Li-ion battery discharge or transient load events on shared power rails.