Monolithic Power Systems Inc. MP3389EF-LF

Overview

MP3389EF-LF from Monolithic Power Systems is a 12-string, step-up white LED driver IC designed for large LCD panel backlighting. It integrates a fixed-frequency current-mode 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 desktop monitors and LCD TVs.

For engineers reviewing the MP3389EF-LF datasheet, MP3389EF-LF pinout, MP3389EF-LF application, or MP3389EF-LF equivalent, key selection criteria include LED string count support, current matching accuracy, external MOSFET gate drive capability, OVP/short-open protection behavior, and dimming frequency programmability via BOSC capacitor.

Technical Context

The MP3389EF-LF implements peak-current-mode control with internal 1.23V oscillator reference and 1.22V ISET regulation voltage, enabling precise per-string current setting via external resistor. Its 12 open-drain LEDX outputs operate as independently controlled current sinks with integrated short/open detection logic.

Protection architecture includes programmable over-voltage protection (OVP threshold set via resistor divider on OVP pin), LED string UVLO (140–220 mV), thermal shutdown at 130°C, and under-voltage lockout (3.4–4.3 V with 200 mV hysteresis). Dimming is implemented either by external PWM signal on DBRT or DC voltage (0.2–1.2 V) converted internally to DPWM using BOSC-timed oscillator.

Key Specifications

Pinout & Package

MP3389EF-LF is housed in a RoHS-compliant, lead-free 28-pin TSSOP package (JEDEC MO-153, 9.7 mm × 4.4 mm, 0.65 mm pitch) with exposed thermal pad for enhanced power dissipation (θ_JA = 32°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ISL97686IRZ-T7A and LM3409QMY/NOPB, MP3389EF-LF provides integrated 12-channel current regulation with external MOSFET drive, programmable boost frequency, and fault-disconnect capability-making it uniquely suited for cost-sensitive, high-channel-count LCD backlight designs where board space and component count are constrained.

Availability

MP3389EF-LF is available at Aetrix Electronics and suitable for desktop LCD monitors, LCD television backlight units, and industrial panel PCs requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP3389EF-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 manufacturing partnerships.

The MP3389 belongs to MPS's WLED backlight driver product line, engineered specifically for large-format LCD panels requiring high channel count, tight current matching, and integrated fault protection in compact form factors.

FAQ

What is the minimum input voltage required for MP3389EF-LF to start up and regulate?

The MP3389EF-LF has an input UVLO rising threshold of 3.4–4.3 V with 200 mV hysteresis. Stable operation begins when VIN exceeds 4.3 V, and the internal 5V LDO (VCC) becomes active above 5.5 V. Below 5.5 V, VCC must be tied to VIN to maintain functionality.

How does the MP3389EF-LF handle an open LED string condition?

When an LED string opens, its corresponding LEDX pin voltage drops below 180 mV. The IC detects this as an open fault, marks off that string, and continues regulating remaining strings using the highest-voltage LEDX pin as feedback reference. If all strings open, the boost converter shuts down.

Can MP3389EF-LF drive more than 12 LED strings?

No. The MP3389EF-LF integrates exactly 12 dedicated current-sink outputs (LED1–LED12). Driving additional strings requires cascading multiple ICs or selecting a different driver architecture; no internal multiplexing or expansion capability is provided.

What is the purpose of the VFAULT pin, and how is it used in system design?

VFAULT controls an external PMOS transistor placed between VIN and the boost converter input. During normal operation, it ramps on slowly for soft-start; during fault or shutdown, it turns off to fully isolate input power, preventing leakage and enabling safe hot-swap or maintenance.

Is the MP3389EF-LF compatible with PWM dimming frequencies above 2 kHz?

Yes - the DBRT pin accepts external PWM signals up to 20 kHz. Table 1 in the datasheet confirms usable duty range down to 7.5% at 5 kHz and 30% at 20 kHz. For >2 kHz, ensure signal rise/fall times <100 ns and low-level voltage <0.4 V to avoid mis-triggering.

Does MP3389EF-LF require external compensation components for loop stability?

Yes. The COMP pin requires an external RC network (typically 1–10 nF capacitor + 10–100 kΩ resistor to GND) to stabilize the boost converter's voltage feedback loop. Component values depend on selected inductor, output capacitance, and load; MPS Application Note AN-107 provides design guidelines.

What thermal derating applies to MP3389EF-LF in TSSOP28 package at 70°C ambient?

With θ_JA = 32°C/W and T_J(MAX) = 150°C, maximum allowable power dissipation at 70°C ambient is (150 − 70) / 32 = 2.5 W. At full 12-string, 60 mA load, typical power dissipation is ~1.8 W - well within safe margin with 2-layer PCB and minimal copper.