Monolithic Power Systems Inc. MP3205DJ-LF-P

Overview

MP3205DJ-LF-P 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 (2.5–6 V input). It regulates LED current via external sense resistor with 104 mV feedback voltage, integrates power MOSFET, and features UVLO, thermal shutdown, and soft-start. Used in compact portable displays requiring high efficiency (>87%) and low-noise LED backlighting.

For engineers reviewing the MP3205DJ-LF-P datasheet, MP3205DJ-LF-P pinout, MP3205DJ-LF-P application, or MP3205DJ-LF-P equivalent, key selection criteria include its TSOT23-5 package footprint, 1.3 MHz switching frequency for small passive size, 104 mV FB threshold for minimal sense loss, EN-controlled PWM dimming support, and integrated current-limit protection at 350 mA.

Technical Context

The MP3205DJ-LF-P implements a constant-frequency peak-current-mode boost architecture with internal N-channel MOSFET switch and 104 mV precision feedback reference. Its 1.3 MHz oscillator enables use of sub-22 µH inductors and <1 µF ceramic output capacitors, reducing solution size for space-constrained handhelds.

Regulation relies on sensing voltage across an external resistor between FB and GND; error amplifier output controls PWM comparator duty cycle. Soft-start ramps current limit over 120 µs to suppress inrush, while thermal shutdown activates at 160°C and UVLO disables operation below 2.45 V (rising).

Key Specifications

Pinout & Package

MP3205DJ-LF-P is housed in a lead-free TSOT23-5 surface-mount package (2.9 mm × 1.6 mm × 0.87 mm), optimized for thermal dissipation (θ_JA = 220°C/W) and PCB area efficiency in portable designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP3012KTR-G1 and LM3407MMX/NOPB, MP3205DJ-LF-P delivers higher integration (integrated MOSFET), lower sense loss (104 mV vs. 200 mV), and comprehensive protection-making it optimal for space- and efficiency-critical single-string portable backlighting.

Availability

MP3205DJ-LF-P is available at Aetrix Electronics and suitable for cell phones, handheld computers & PDAs, and digital still cameras requiring stable component supply, RoHS-compliant packaging, and long-term production continuity.

Supply support for MP3205DJ-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, headquartered in Kirkland, WA, with global design and support centers.

The MP3205 belongs to MPS's LED backlight driver product line, engineered specifically for ultra-compact, battery-powered portable devices demanding high efficiency, low EMI, and seamless integration with single-cell Li-ion sources.

FAQ

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

The MP3205DJ-LF-P is rated to drive up to 5 white LEDs in series, assuming typical forward voltage of 3.2–3.6 V per LED and input voltage ≥3.6 V. At VIN = 3.6 V, full regulation is maintained for 3–4 LEDs; 5-LED operation requires VIN ≥4.2 V to ensure sufficient headroom for the boost stage and sense resistor drop.

Can the MP3205DJ-LF-P operate with a 2.5 V input supply?

Yes - the MP3205DJ-LF-P supports input voltages down to 2.5 V, enabling operation during deep discharge of Li-ion batteries. However, at 2.5 V input, maximum achievable LED string voltage drops to ~12 V, limiting practical use to ≤3 white LEDs at full current. UVLO releases at 2.45 V (rising), ensuring reliable restart after brownout.

How is LED current set, and what resistor value yields 20 mA?

LED current is set by the external sense resistor (R_SENSE) between FB and GND using I_LED = 104 mV / R_SENSE. For 20 mA, R_SENSE = 104 mV / 20 mA = 5.2 Ω. The datasheet specifies 5.2 Ω (±1%) as the nominal value, yielding 20 mA ±2% at room temperature with proper layout and thermal management.

Does the MP3205DJ-LF-P support analog dimming?

Yes - analog dimming is supported by injecting controlled current into the FB pin via an external resistor network, effectively reducing the effective sense voltage and lowering regulated LED current. Figure 6 in the datasheet shows a DC voltage-controlled implementation; dimming range is linear from 0 mA to full-scale current, limited only by FB pin bias current (±300 nA) and noise immunity.

What is the purpose of the 104 mV feedback voltage specification?

The 104 mV feedback voltage is the precise internal reference used by the error amplifier to regulate LED current. It directly determines the voltage drop across the external sense resistor, enabling accurate current setting with minimal power loss. This low value improves efficiency - e.g., at 20 mA, power dissipated in a 5.2 Ω resistor is only 2.08 mW versus 8 mW for a 400 mV reference.

Is the TSOT23-5 package thermally adequate for continuous 350 mA operation?

The TSOT23-5 package has θ_JA = 220°C/W. Under worst-case conditions (VIN = 2.5 V, V_OUT = 21 V, I_LED = 20 mA × 5 = 100 mA), power dissipation is ~0.5 W; junction rise ≈ 110°C above ambient. With proper copper pour and airflow, continuous operation is viable. For 350 mA current-limit events, thermal shutdown at 160°C provides fail-safe protection.