Monolithic Power Systems Inc. MP3393EF-LF-P

Overview

MP3393EF-LF-P from Monolithic Power Systems is an 8-string white LED step-up controller IC designed for large-panel LCD backlighting. It drives external NMOS and PNP transistors to regulate up to 300mA per string with 1.2% current matching accuracy, 202mV FB regulation voltage, and programmable 120–160kHz switching frequency. Used in LCD TVs and monitors requiring precise multi-string current control.

For engineers reviewing the MP3393EF-LF-P datasheet, MP3393EF-LF-P pinout, MP3393EF-LF-P application, or MP3393EF-LF-P equivalent, key selection criteria include its external transistor architecture, daisy-chain capability for >8 strings, OVP/short/open protection logic, thermal shutdown behavior, and dual analog/PWM dimming interface compatibility.

Technical Context

The MP3393EF-LF-P implements peak-current-mode control with a fixed-frequency oscillator set via ROSC (115kΩ → 140kHz typ). Its internal 10V LDO powers gate drivers and control circuitry, while eight independent CTLx/FBx pairs regulate LED string current using external PNP transistors and sense resistors.

Protection logic includes open-string detection via CTLx UVLO (210mV threshold), short-string detection via CTLx OV (6.4V threshold), OVP triggered at 1.23V on the OVP pin, and thermal shutdown at 150°C. Fault status is reported through open-drain VFAULT and FF pins.

Key Specifications

Pinout & Package

TSSOP28EP package with exposed thermal pad (connected to GND); 0.65mm pitch, RoHS-compliant lead-free finish.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-channel LED controller applications.

Compared with MPQ3393-AEC1, the MP3393EF-LF-P lacks automotive qualification but offers identical performance at lower cost for industrial/commercial use; compared with RT9397BF, it delivers 7.5× higher per-string current and external FET flexibility at the expense of board space and external component count.

Availability

MP3393EF-LF-P is available at Aetrix Electronics and suitable for LCD TV backlighting, professional monitor design, and industrial HMI development requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for MP3393EF-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 MP3393 product line targets large-format LCD backlight systems, delivering scalable, fault-resilient LED current control with minimal external components and industry-leading current matching.

FAQ

What is the maximum LED string current supported by MP3393EF-LF-P?

The MP3393EF-LF-P supports up to 300mA per string, confirmed by its 1.2% current matching specification across 8 channels and absolute maximum CTLx sink current of 13.5mA - sufficient to drive high-hFE PNP transistors for 300mA loads. This is validated in the Electrical Characteristics table under "Maximum Channel Current Over 350mA" (note: "over 350mA" refers to total system capability with appropriate external components, not per-string).

Can MP3393EF-LF-P operate without an external MOSFET?

No. The MP3393EF-LF-P is a controller-only IC: it requires an external NMOS for the boost switch (driven by GATE pin) and external PNP transistors for LED string current regulation (driven by CTLx pins). It contains no power switches internally - this architecture enables higher voltage/current scalability and thermal separation.

How does open-string protection work on MP3393EF-LF-P?

When an LED string opens, its CTLx pin voltage drops below 210mV (UVLO threshold). The IC detects this condition, disables the affected string, and raises output voltage until the OVP pin reaches 1.23V - triggering shutdown. Remaining functional strings continue regulation, and the FF pin pulls low to signal the fault.

Is daisy-chaining supported between different MP3393 package variants?

Yes. MP3393EF-LF-P (TSSOP28EP) can be daisy-chained with MP3393EY-LF-P (SOIC28) or other MP3393 variants, as pinout and logic are identical. Critical connections - COMP, VCC, EN, DIM, and ISENSE (tied to GND on slave) - function identically across packages per the Application Information section.

What is the purpose of the VFAULT pin?

VFAULT drives the gate of an external PMOS transistor placed between VIN and the boost converter input. During normal operation, VFAULT rises to VIN to turn on the PMOS. During faults (OVP, thermal shutdown, etc.), VFAULT drops to ~0V, turning off the PMOS and physically isolating input power from the faulty stage - enhancing system safety.

Does MP3393EF-LF-P support I²C or SPI communication?

No. The MP3393EF-LF-P is an analog-controlled LED driver with no digital interface. Dimming and configuration are handled exclusively through analog voltage (DIM pin), resistor programming (ROSC, OVP divider), and discrete logic signals (EN). All settings are hardware-defined, not register-configurable.

What is the minimum recommended input capacitor value?

The datasheet recommends a 4.7µF ceramic capacitor in parallel with a 220µF electrolytic capacitor at the VIN pin. This combination provides low-impedance decoupling across high-frequency switching noise (120–160kHz) and low-frequency input ripple, preventing instability and reducing EMI radiation.