Monolithic Power Systems Inc. MP3394SGS-Z

Overview

MP3394SGS-Z from Monolithic Power Systems is a step-up white LED driver IC with four independent current-regulated channels, designed for large-size LCD panel backlighting. It operates from 5V to 28V input, delivers up to 200mA per string, achieves 2.5% inter-string current matching, and supports programmable switching frequency (140–670 kHz) via external ROSC resistor. Used in flat-panel TVs and monitors where precise brightness uniformity across multiple LED strings is critical.

For engineers reviewing the MP3394SGS-Z datasheet, MP3394SGS-Z pinout, MP3394SGS-Z application, or MP3394SGS-Z equivalent, key selection considerations include its 4-string current balancing architecture, dual dimming modes (external PWM and DC-input burst PWM), open/short LED fault protection, cascading capability for expanded channel count, and SOIC16 package thermal performance (θJA = 80°C/W).

Technical Context

The MP3394SGS-Z employs peak-current-mode control with fixed-frequency operation, using an external MOSFET driven by a 6.8V-rated gate driver (4Ω sourcing / 2Ω sinking). Its internal error amplifier regulates output voltage by dynamically selecting the highest active LEDX pin voltage to maintain sufficient bus voltage across all strings.

Dimming is implemented via two distinct paths: DBRT accepts either a 100Hz–20kHz external PWM signal (with BOSC grounded via 100kΩ), or a 0.2–1.2V DC analog input that generates an internally synchronized burst-PWM waveform whose frequency is set by CBOSC (f_BOSC = 3.5 / C_BOSC(nF)). Protection includes OVP threshold detection at 1.23V on the OVP pin, LEDX UVLO at 196mV, and thermal shutdown at 150°C.

Key Specifications

Pinout & Package

MP3394SGS-Z uses the SOIC16 package (10.3mm × 6.1mm, 1.27mm pitch) with exposed thermal pad connected to GND. Pin functions are validated per Monolithic Power Systems Rev. 1.03 datasheet (2013).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 4-channel WLED driver applications.

Compared with ISL97694AIRTZ-T7A and LM3409QMY/NOPB, MP3394SGS-Z uniquely combines external MOSFET flexibility (supporting >30V V_DS), wide 5–28V input range, and true 4-string integration in SOIC16-making it optimal for cost-sensitive, thermally demanding large-panel backlighting where reliability and design simplicity are prioritized.

Availability

MP3394SGS-Z is available at Aetrix Electronics and suitable for desktop LCD flat panel displays, 2D/3D LCD TVs, and industrial HMI monitors requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP3394SGS-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 over 20 years of leadership in DC/DC conversion and LED driver technology.

The MP3394 product line targets large-format LCD backlighting applications, emphasizing high-current precision, multi-string synchronization, and robust fault tolerance in thermally challenging environments.

FAQ

What is the maximum allowable LED string voltage for MP3394SGS-Z?

The absolute maximum voltage at any LEDX pin is 55V, but practical string voltage is limited by the external MOSFET's V_DS rating and OVP threshold setting. With a 28V input and typical 10W LED string, output voltages up to 42V are achievable using a 60V-rated MOSFET and properly scaled OVP resistor divider.

Can MP3394SGS-Z drive more than four LED strings?

Yes-two or more MP3394SGS-Z ICs can be cascaded using shared VCC and COMP connections, enabling 8-, 12-, or 16-string configurations from a single boost inductor. The master IC drives the MOSFET while slave units regulate additional strings, maintaining 2.5% current matching across all channels.

How does the MP3394SGS-Z handle an open LED string fault?

When an LED string opens, the corresponding LEDX pin voltage drops below 196mV, triggering open-string detection. The IC disables that string, raises output voltage until the remaining strings reach regulation, and continues operation with reduced total current-ensuring partial backlight functionality rather than full shutdown.

What is the minimum dimming frequency supported in DC-input PWM mode?

In DC-input PWM mode, the internal dimming oscillator frequency is set by CBOSC. Using a 35nF capacitor yields ~100Hz (f_BOSC = 3.5 / C_BOSC), which is the lowest recommended frequency to avoid visible flicker. Frequencies below 100Hz may cause perceptible modulation in static scenes.

Is thermal derating required for continuous 200mA/string operation in SOIC16?

Yes-SOIC16 has θ_JA = 80°C/W. At 200mA/string and 12V input, power dissipation exceeds 1.2W. With 25°C ambient, junction temperature reaches ~125°C. A 2cm² copper pour under the exposed pad reduces θ_JA to ~55°C/W, enabling full 200mA operation without thermal throttling.

Does MP3394SGS-Z require external components for basic operation?

Yes-minimum external components include: input capacitor (4.7μF ceramic + 220μF electrolytic), output capacitor (4.7μF ceramic + 22μF electrolytic), boost inductor, external N-MOSFET, current-sense resistor (R_SENSE), ISET resistor, ROSC resistor, and OVP divider resistors. No internal compensation or power switches are integrated.

How is current matching maintained across LED strings with varying forward voltages?

MP3394SGS-Z uses four matched internal current sources referenced to the same 1.22V ISET voltage. Each LEDX pin operates as a low-dropout current sink (300mV regulation voltage), allowing independent current regulation regardless of string V_F mismatch-achieving 2.5% matching even with ±0.3V V_F variation.