Monolithic Power Systems Inc. MP3389EY-LF

Overview

MP3389EY-LF 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 with 12 matched internal current sinks (±2.5% matching), supports 5V–28V input, delivers up to 60mA per string, and regulates LED current via an external ISET resistor (1.22V reference). Used in LCD TVs and flat-panel monitors requiring uniform brightness across high-channel-count WLED arrays.

For engineers reviewing the MP3389EY-LF datasheet, MP3389EY-LF pinout, MP3389EY-LF application, or MP3389EY-LF equivalent, key selection criteria include programmable switching frequency (100–500 kHz), dual PWM/DC dimming control, open/short LED protection, 550mV current-sense voltage headroom, and SOIC-28 thermal performance (θJA = 60°C/W).

Technical Context

The MP3389EY-LF implements peak-current-mode control with programmable oscillator (via OSC pin resistor) and internal 5V LDO (VCC) for gate drive and logic. Its 12 open-drain LEDX outputs operate as current-sink switches with independent dimming control, using either external PWM on DBRT or internally generated DPWM (set by BOSC capacitor).

Protection architecture includes OVP (triggered at 1.23V on OVP pin), LED string fault detection (open: V_LEDX < 180mV; short: V_LEDX > 5.5V), UVLO (3.9V threshold), and thermal shutdown (130°C). The ISENSE pin enables cycle-by-cycle inductor current limiting, while VFAULT controls an external PMOS for input-output isolation during fault conditions.

Key Specifications

Pinout & Package

MP3389EY-LF is housed in a 28-pin SOIC package (body width 7.5mm, pitch 1.27mm), optimized for industrial-grade thermal dissipation (θJA = 60°C/W) and compatibility with standard reflow processes.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP3389EF-LF, MP3389EY-LF trades 28°C/W higher θJA for easier assembly and lower PCB fabrication cost; versus LM3409QMY/NOPB, it delivers 12× integration, ±2.5% matching, and coordinated fault response-reducing BOM count by 11 drivers and eliminating 12× current calibration steps.

Availability

MP3389EY-LF is available at Aetrix Electronics and suitable for LCD TV backlighting, industrial HMI displays, commercial signage, and medical monitor applications requiring stable component supply, RoHS-compliant packaging, and long-term lifecycle support.

Supply support for MP3389EY-LF 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 through authorized partners.

The MP3389 product line targets large-format LCD backlighting, delivering integrated step-up control and precision multi-string current regulation to replace discrete boost + current-source solutions in cost- and space-sensitive displays.

FAQ

What is the minimum recommended input voltage for reliable startup?

The MP3389EY-LF has a 3.9V input UVLO threshold with 200mV hysteresis. Reliable startup requires VIN ≥ 4.1V after accounting for source impedance drop; below this, the internal VCC regulator cannot energize the gate driver or control logic, and the device remains in shutdown.

How does the MP3389EY-LF handle an open LED string during operation?

When an LED string opens, its LEDX pin voltage drops below 180mV. The IC detects this within one switching cycle, marks off that string, and continues regulating remaining strings using the highest-voltage active LEDX pin as feedback reference-maintaining backlight output without full shutdown.

Can the MP3389EY-LF drive LED strings with different forward voltages?

Yes. The IC automatically selects the highest active LEDX pin voltage as the feedback reference, ensuring sufficient bus voltage for all strings. Strings with lower V_F are current-regulated normally; mismatched V_F does not affect current accuracy or matching.

What is the purpose of the VFAULT pin, and how is it used externally?

VFAULT drives the gate of an external PMOS transistor placed between VIN and the boost converter input. During normal operation, it ramps up slowly to limit inrush; during UVLO, OVP, or thermal fault, it pulls low to disconnect input power-preventing backfeed and enabling safe fault containment.

Is the MP3389EY-LF compatible with PWM dimming frequencies above 2kHz?

Yes, but with reduced minimum duty cycle. At 5kHz, the lowest usable dimming duty is 7.5%; at 20kHz, it is 30%. For high-frequency flicker elimination, use DC-input DPWM mode with BOSC capacitor-where dimming frequency is decoupled from system clock and set independently.

Does the ISET pin require a specific capacitor value for stability?

No capacitor is required on ISET. It is a precision voltage reference node (1.22V, ±2.5mV) with 100nA max leakage. Adding capacitance risks phase shift in the current regulation loop; R_SET must be directly connected to GND with minimal trace length to preserve accuracy.

What thermal derating applies to the SOIC-28 package at 85°C ambient?

At T_A = 85°C, maximum continuous power dissipation is 1.05W (calculated as (150°C − 85°C) / 60°C/W). Exceeding this causes thermal shutdown; PCB copper area and airflow must be designed to maintain T_J ≤ 125°C for rated 60mA/string operation.