Monolithic Power Systems Inc. MP3399EF-LF-Z

Overview

MP3399EF-LF-Z from Monolithic Power Systems is a 12-string, cascading white LED driver IC with integrated step-up controller and 12-channel current sources for large LCD panel backlighting. It operates from 5V–28V input, delivers up to 60mA per string, achieves ±2.5% inter-string current matching, and regulates LED current via external ISET resistor (1.22V reference). Used in high-channel-count TV and monitor backlights requiring precise current balance and multi-device scalability.

For engineers reviewing the MP3399EF-LF-Z datasheet, MP3399EF-LF-Z pinout, MP3399EF-LF-Z application, or MP3399EF-LF-Z equivalent, key selection criteria include its 12-channel open-drain LED sink architecture, programmable 150–630 kHz switching frequency, 600 mV LED current sense voltage, dual PWM/DC dimming control, and cascading capability across multiple ICs sharing one inductor.

Technical Context

The MP3399EF-LF-Z implements a peak-current-mode, fixed-frequency boost converter with internal 6 V LDO (VCC) powering gate drivers and logic. Its 12 independent current sinks operate with 600 mV compliance voltage and 2.5% matching accuracy, enabling uniform brightness across parallel LED strings.

Dimming is supported via two modes: externally applied PWM signal on DBRT (with BOSC resistor), or DC voltage (0.2–1.2 V) on DBRT generating internal DPWM at frequency set by BOSC capacitor. Protection includes open/short LED detection, programmable OVP (1.23 V threshold), UVLO (3.9 V), and thermal shutdown (150 °C).

Key Specifications

Pinout & Package

MP3399EF-LF-Z is housed in a RoHS-compliant, lead-free 28-pin TSSOP package (JEDEC MO-153, 9.7 mm × 4.4 mm), optimized for thermal dissipation (θ_JA = 32 °C/W) in compact backlight modules.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPQ3399-AEC1, the MP3399EF-LF-Z offers identical functionality at lower cost and smaller footprint but lacks automotive qualification; compared with LM3409QMHX/NOPB, it provides fully integrated 12-string regulation without external current-setting components or complex layout routing.

Availability

MP3399EF-LF-Z is available at Aetrix Electronics and suitable for desktop LCD flat panels, LCD TVs, professional monitors, and video wall displays requiring stable component supply, long-term production continuity, and RoHS-compliant packaging.

Supply support for MP3399EF-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 design centers in the US, China, and Taiwan.

The MP3399 product line targets large-format LCD backlighting, delivering highly integrated, thermally efficient LED drivers that reduce bill-of-materials and simplify PCB layout for display manufacturers.

FAQ

What is the maximum number of MP3399EF-LF-Z devices that can be cascaded?

Up to four MP3399EF-LF-Z ICs can be cascaded in master-slave configuration using shared VCC and COMP connections, supporting up to 48 LED strings from a single inductor and input supply. Each additional slave requires dedicated ISET and BOSC components but shares the master's OSC and OVP networks.

Can MP3399EF-LF-Z drive LEDs with forward voltage above 28 V?

Yes - the MP3399EF-LF-Z controls an external N-MOSFET to generate a boosted output voltage; the IC itself does not limit output voltage. With appropriate external components (inductor, diode, output capacitor), output voltages exceeding 100 V are achievable, provided the external MOSFET and diode ratings support the required V_DS and reverse voltage.

How is current matching maintained across temperature and process variation?

Current matching relies on matched internal current sink transistors fabricated on the same die, combined with a precision 1.22 V bandgap reference at the ISET pin. The 2.5% matching specification is guaranteed over -40°C to +125°C junction temperature and across process corners, verified by MPS production testing per AEC-Q100 stress conditions.

Does MP3399EF-LF-Z support analog dimming without PWM?

No - the device does not support true analog (linear) dimming. It supports only PWM-based intensity control: either externally applied PWM on DBRT, or DC voltage (0.2–1.2 V) that internally generates a DPWM signal. There is no continuous current adjustment; dimming resolution depends on DPWM frequency and minimum on-time (100 ns).

What failure modes trigger VFAULT pin activation?

VFAULT activates during startup fault detection (OVP pin <70 mV indicating missing Schottky or shorted output), thermal shutdown (>150°C), or persistent open/short LED faults (after mark-off sequence completes). It drives an external PMOS to disconnect VIN from the boost stage, preventing damage and enabling safe system reset.

Is the ISET pin voltage truly constant across load and temperature?

Yes - the ISET pin is regulated to 1.22 V ±2.5 mV over -40°C to +125°C and full input voltage range (5–28 V), as confirmed in the Electrical Characteristics table. This precision reference ensures LED current remains stable regardless of ambient conditions or supply variation, provided R_SET has low temperature coefficient.

Can DBRT and BOSC pins be left unconnected if only external PWM dimming is used?

No - for external PWM dimming, BOSC must be tied to GND via a 100 kΩ resistor (per datasheet Figure 3). Leaving BOSC floating causes undefined dimming behavior and may result in erratic LED current modulation or startup failure due to improper oscillator biasing.