Monolithic Power Systems Inc. MP3397EF-LF

Overview

MP3397EF-LF from Monolithic Power Systems is a 4-string, step-up white LED driver IC designed for large-size LCD panel backlighting. It delivers up to 350mA per string with 2.5% current matching accuracy, operates from 5V–28V input, uses external MOSFET control via GATE pin, and supports both external PWM and DC-input burst dimming modes in desktop monitors and 2D/3D TVs.

For engineers reviewing the MP3397EF-LF datasheet, MP3397EF-LF pinout, MP3397EF-LF application, or MP3397EF-LF equivalent, key selection criteria include programmable switching frequency (150–500 kHz), open/short LED protection logic, OVP threshold set via resistor divider on OVP pin, and cascading capability for 8+ string configurations using multiple ICs sharing one boost stage.

Technical Context

The MP3397EF-LF implements a peak-current-mode, fixed-frequency step-up controller with four independent current-regulated open-drain LED sinks (LED1–LED4). Each string's current is set by an external resistor on ISET (regulated at 1.23 V), and matching is maintained within ±2.5% via internal current sources with ≤390 mV regulation voltage.

Dimming is implemented via two distinct paths: DBRT accepts either a 100 Hz–20 kHz external PWM signal (with BOSC tied to GND via 100 kΩ) or a 0.2–1.2 V DC analog input that drives an internal DPWM oscillator (frequency set by capacitor on BOSC). Protection includes OVP (triggered at 1.23 V on OVP pin), LEDX UVLO (196 mV), short-string detection (>6.3 V on LEDX), and thermal shutdown at 150 °C.

Key Specifications

Pinout & Package

MP3397EF-LF is housed in a 16-pin SOIC package (body width 3.90 mm, lead pitch 1.27 mm), RoHS-compliant and lead-free per MPS green status. Thermal resistance θ_JA = 80 °C/W on 4-layer JEDEC board.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP3394GF-Z and LM3409QMY/NOPB, MP3397EF-LF uniquely integrates 4-channel regulation, programmable dimming frequency, and cascading-reducing total solution size and component count for large-panel backlighting.

Availability

MP3397EF-LF is available at Aetrix Electronics and suitable for desktop LCD flat panel displays, 2D/3D LCD TVs, and industrial human-machine interfaces requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP3397EF-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 MP3397 belongs to MPS's WLED backlight driver product line, engineered specifically for energy-efficient, high-accuracy LCD panel illumination in consumer and industrial displays with stringent thermal and reliability requirements.

FAQ

What is the maximum allowable LED string voltage supported by MP3397EF-LF?

The MP3397EF-LF does not impose a fixed maximum string voltage; instead, it regulates output based on the highest forward voltage among the 4 strings. With typical 3.3 V per white LED and up to 14 LEDs in series, the output can reach ~46 V. The OVP threshold is programmable via the OVP pin resistor divider to safely limit this voltage.

Can MP3397EF-LF drive more than 4 LED strings?

Yes-two or more MP3397EF-LF ICs can be cascaded using shared VCC and COMP connections while disabling slave GATE drivers. This configuration supports up to 8 or more strings driven from a single boost inductor and diode, preserving efficiency and reducing component count versus discrete solutions.

How does the MP3397EF-LF handle an open LED string fault?

When an LED string opens, its corresponding LEDX pin voltage drops below 196 mV, triggering open-string detection. The IC marks that string as inactive, continues regulating remaining strings, and maintains output voltage just sufficient for the highest-voltage active string-preventing overvoltage and allowing partial illumination.

What is the minimum recommended input capacitance for stable operation?

MPS recommends a 4.7 µF X5R/X7R ceramic capacitor in parallel with a 220 µF electrolytic capacitor at VIN. This combination suppresses high-frequency switching noise and limits surge current into the boost stage, especially critical at low input voltages (5–7 V) where ripple current is highest.

Is the MP3397EF-LF compatible with 3.3 V logic control signals?

No-the EN pin requires ≥1.8 V to enable and ≤0.6 V to disable, but the DBRT pin expects 0.2–1.2 V for DC dimming or ≥1.2 V amplitude for external PWM. Direct 3.3 V logic must be level-shifted or attenuated; a resistive divider or dedicated buffer is required for safe interface.

Does MP3397EF-LF support analog (DC) dimming without PWM?

No-it does not support true analog current adjustment. Its "DC-input" mode converts a 0.2–1.2 V analog voltage into an internally generated burst-mode PWM signal (DPWM), maintaining digital switching efficiency while enabling smooth brightness control from MCU DAC outputs.

What thermal derating applies above 25°C ambient?

With θ_JA = 80 °C/W, junction temperature rise is 80 × P_D. At 25°C ambient, max power dissipation before reaching 125°C T_J is 1.25 W. Above 25°C, allowable power decreases linearly: P_D(MAX) = (125 − T_A) / 80. Layout with copper pour and thermal vias is strongly advised for >500 mW loads.