Monolithic Power Systems Inc. MP3397EF-LF-Z

Overview

MP3397EF-LF-Z 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, and uses external MOSFET control via GATE pin to boost output up to 28V. Its integrated 6V LDO (VCC), programmable switching frequency (145–600 kHz), and dual-mode PWM dimming support desktop monitors and 2D/3D TVs.

For engineers reviewing the MP3397EF-LF-Z datasheet, MP3397EF-LF-Z pinout, MP3397EF-LF-Z application, or MP3397EF-LF-Z equivalent, key selection criteria include LED string current regulation accuracy, open/short LED protection behavior, cascading capability across multiple ICs, and compatibility with external N-channel MOSFET gate drive requirements.

Technical Context

The MP3397EF-LF-Z implements a peak-current-mode, fixed-frequency boost controller with four independent current-sink channels. Each channel uses an internal current source regulated to 1.23V at ISET, enabling precise per-string current setting via external resistor. The IC features dual dimming control: external PWM applied to DBRT (with BOSC grounded via resistor) or DC-input PWM using a BOSC capacitor to generate internal DPWM.

Protection architecture includes per-string voltage monitoring on LED1–LED4 pins for open-circuit detection (triggered below 196mV) and short-circuit detection (above 6.3V), plus OVP threshold programming via resistor divider on OVP pin (trip at 1.23V), ISENSE-based cycle-by-cycle current limiting, UVLO (4.2V rising), and thermal shutdown at 150°C.

Key Specifications

Pinout & Package

MP3397EF-LF-Z is housed in a 16-pin SOIC package with standard 1.27 mm pitch, 10.0 mm × 6.2 mm body, and exposed pad not present. Thermal resistance θ_JA = 80°C/W (4-layer PCB).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP3397EF-LF-Z, MPQ3326-AEC1 trades string count and current capacity for automotive compliance and integration, while LM3409QMY/NOPB offers topology freedom at the cost of added external components and design effort-making MP3397EF-LF-Z optimal for cost-sensitive, high-channel-count LCD backlighting.

Availability

MP3397EF-LF-Z 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, RoHS-compliant packaging, and long-term production continuity.

Supply support for MP3397EF-LF-Z 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 core expertise in DC/DC conversion, LED drivers, and motor control.

The MP3397 product line targets large-format LCD backlighting systems, delivering high-accuracy current regulation, robust fault handling, and scalable multi-IC architectures for commercial and industrial display applications.

FAQ

What is the maximum LED string voltage the MP3397EF-LF-Z can support?

The MP3397EF-LF-Z does not define a fixed maximum LED string voltage; instead, it regulates current while allowing output voltage to rise as needed-up to the breakdown limit of the external MOSFET and diode. With a 28V input and typical 100V-rated MOSFET, output voltages exceeding 40V are achievable depending on LED count and forward voltage. The OVP pin must be configured to safely clamp this voltage before reaching component limits.

Can MP3397EF-LF-Z drive more than four LED strings?

Yes-MP3397EF-LF-Z supports cascading: two or more ICs can operate in parallel from a single boost inductor and power stage. The master IC drives the MOSFET while slave ICs contribute additional current sinks (e.g., two ICs = 8 strings). COMP pins are tied together for shared voltage regulation, and EN/DBRT signals are applied to all devices for synchronized control.

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

When an LED string opens, its corresponding LEDX pin voltage drops below 196mV, triggering open-string detection. The IC marks that string as faulty and continues regulating remaining strings using the highest active LEDX voltage as feedback reference. If all strings open, the IC disables the boost converter and enters shutdown until reset via EN pin toggle.

What is the minimum recommended input capacitance for stable operation?

The datasheet recommends a 4.7µF X5R/X7R ceramic capacitor in parallel with a 220µF electrolytic capacitor at VIN. This combination suppresses high-frequency switching noise and handles surge current during startup and load transients. Ceramic capacitor ESR must be low (<50 mΩ), and placement must minimize loop area between VIN, GND, and CIN to reduce EMI.

Is the MP3397EF-LF-Z compatible with PWM dimming frequencies above 20 kHz?

No-the MP3397EF-LF-Z specifies external PWM dimming support up to 20 kHz (per Table 1). Frequencies above this range may cause inconsistent dimming response or reduced duty-cycle resolution due to internal sampling limitations. For >20 kHz operation, use DC-input PWM dimming mode with BOSC capacitor to generate internal DPWM at 1–2 kHz, which avoids audible noise while maintaining full 0–100% control range.

Does the MP3397EF-LF-Z require an external Schottky diode?

Yes-an external Schottky diode is required in the boost converter path to prevent reverse current flow and ensure efficient energy transfer from inductor to output capacitor. The diode must have sufficient voltage rating (>1.5× expected VOUT) and current handling capability (>1.5× peak inductor current), with low forward voltage (≤0.5V) to minimize conduction loss and thermal stress.

What is the purpose of the ISENSE pin when not cascading?

When not cascading, the ISENSE pin must be tied directly to GND-not left floating-to disable current-sense functionality and avoid erratic switching behavior. Leaving ISENSE unconnected risks false overcurrent triggering or unstable regulation, as the internal comparator interprets noise or leakage as valid current-sense signals.