Monolithic Power Systems Inc. MP3389EF-LF-P

Overview

MP3389EF-LF-P from Monolithic Power Systems is a 12-string, step-up white LED driver IC designed for large LCD panel backlighting. It integrates a current-mode fixed-frequency boost controller and 12 matched current sinks (±2.5% matching), supports 5V–28V input, delivers up to 60mA per string, and features programmable switching frequency (100–500 kHz) and dual-mode PWM/DC dimming. Used in high-brightness TV and monitor backlights.

For engineers reviewing the MP3389EF-LF-P datasheet, MP3389EF-LF-P pinout, MP3389EF-LF-P application, or MP3389EF-LF-P equivalent, key selection criteria include LED string count support, current matching accuracy, OVP/short/open protection behavior, thermal shutdown threshold (130°C), and compatibility with external N-MOSFET gate drive requirements.

Technical Context

The MP3389EF-LF-P implements peak-current-mode control with programmable oscillator (via OSC pin resistor) and internal 5V LDO (VCC) for gate driver and logic supply. Its 12 open-drain LEDX outputs each regulate current using a 1.22V reference at ISET, achieving 2.5% inter-string matching via matched current sources.

Dimming is implemented either by external PWM on DBRT (with BOSC tied to GND via 100kΩ) or DC voltage (0.2–1.2V) converted internally to DPWM; dimming frequency is set by capacitor on BOSC (1.2–2 kHz typical). Protection includes OVP (1.23V threshold on OVP pin), LED short detection (>5.5V on LEDX), open-string marking (<180mV), and thermal shutdown at 130°C.

Key Specifications

Pinout & Package

MP3389EF-LF-P uses a RoHS-compliant 28-pin TSSOP package (JEDEC MO-153, 9.7mm × 4.4mm, 0.65mm pitch) with exposed thermal pad. Pin 1 marked by dot; pins 1 and 28 are NC.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 12-channel WLED driver applications.

Compared with ISL97686IRZ-T7A and LM3409QMY/NOPB, MP3389EF-LF-P uniquely combines 12-channel boost control, ±2.5% matching, and integrated gate drive in one TSSOP package-reducing solution size by >40% and eliminating per-string compensation design effort.

Availability

MP3389EF-LF-P is available at Aetrix Electronics and suitable for LCD TV backlighting, industrial HMI panels, and professional flat-panel displays requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for MP3389EF-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 focus on efficiency, integration, and thermal robustness.

The MP3389 product line targets large-format LCD backlighting, delivering highly integrated, fault-resilient LED drivers with minimal external components and industry-leading current matching.

FAQ

What is the minimum recommended input voltage for reliable startup?

The MP3389EF-LF-P has an input UVLO threshold of 3.9V (typical) with 200mV hysteresis. Reliable startup occurs at ≥4.3V, but the recommended operating range starts at 5V to ensure stable VCC regulation and sufficient headroom for boost conversion. Below 5V, tie VCC to VIN per datasheet guidance.

Can MP3389EF-LF-P drive more than 12 LED strings?

No. The device integrates exactly 12 dedicated current-sink outputs (LED1–LED12); unused pins must be connected to VIN per datasheet instructions. Driving additional strings requires cascading multiple MP3389EF-LF-P units with synchronized dimming signals-no internal expansion capability exists.

How does open-string protection operate without external circuitry?

When an LED string opens, its corresponding LEDX pin voltage drops below 180mV. The IC detects this condition, marks off the faulty string, and re-regulates output voltage using only the remaining active strings. No external comparators or logic are needed-the function is fully embedded in analog control blocks.

What is the maximum allowable switching frequency and how is it set?

The maximum switching frequency is 500kHz, achieved with ROSC = 136kΩ (f_SW ≈ 67850 / R_OSC(kΩ)). Higher frequencies reduce inductor size but increase switching losses; the IC guarantees stable operation up to 500kHz with proper gate drive and layout.

Does MP3389EF-LF-P support analog dimming?

No. It supports only PWM-based dimming: either external PWM applied to DBRT (with BOSC grounded via 100kΩ) or DC voltage (0.2–1.2V) converted internally to DPWM. There is no true analog (linear) current adjustment-dimming resolution depends on PWM frequency and duty cycle granularity.

What thermal pad soldering guidelines apply to the TSSOP-28 package?

The exposed thermal pad (pin 28 side) must be soldered to a solid copper thermal plane on the PCB using ≥4 thermal vias (0.3mm diameter) filled or capped. Per JEDEC MO-153, pad area should match footprint (≈5.5mm × 4.4mm); insufficient thermal relief increases θ_JA beyond 32°C/W and risks thermal shutdown.

Is the VFAULT pin actively driven during normal operation?

Yes. During startup and normal operation, VFAULT provides a controlled ramp-up voltage to turn on an external PMOS for input-to-output isolation. When disabled or during fault, it actively pulls low to disconnect the PMOS. It is not a passive open-drain flag-it's a sourced gate-drive signal with soft-start timing.