Monolithic Power Systems Inc. MP3394SGY-Z

Overview

MP3394SGY-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 resistor. Used in flat-panel TVs and monitors where precise brightness uniformity across multiple LED strings is critical.

For engineers reviewing the MP3394SGY-Z datasheet, MP3394SGY-Z pinout, MP3394SGY-Z application, or MP3394SGY-Z equivalent, key selection considerations include its SOIC20 package thermal performance (θJA = 72°C/W), dual dimming modes (external PWM and DC-input burst PWM), open/short LED fault protection, cascading capability for 8+ strings, and OVP threshold programmability via resistor divider.

Technical Context

The MP3394SGY-Z employs peak-current-mode control with fixed-frequency operation, using an external MOSFET driven by a 4Ω/2Ω gate driver to boost input voltage to ≥28V output. Its internal 5.8V LDO (VCC) powers gate drive and logic, with UVLO at 3.9V (200mV hysteresis) and thermal shutdown at 150°C.

Four matched current sources regulate LED string current via ISET pin (1.22V reference), achieving 2.5% matching accuracy. Protection includes programmable OVP (1.23V threshold), LEDX UVLO (196mV), short-string detection (>6.1V on LEDx), and open-string marking-ensuring stable operation even with partial string failure.

Key Specifications

Pinout & Package

MP3394SGY-Z is housed in a 20-pin SOIC package with exposed pad (not electrically connected per datasheet; pin 4, 6, 15, 16 are NC). The SOIC20 footprint provides improved thermal performance over TSSOP16EP/SOIC16 variants, supporting higher continuous power delivery in backlight applications.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multi-string WLED driver applications.

Compared with MP3394SGY-Z, the TSSOP16EP variant offers superior thermal performance in compact layouts but demands rigorous PCB thermal design, while the SOIC16 version trades thermal headroom for lower BOM cost - making the SOIC20 the balanced choice for mainstream TV and monitor designs requiring reliability and manufacturability.

Availability

MP3394SGY-Z is available at Aetrix Electronics and suitable for desktop LCD flat panel displays, 2D/3D LCD TVs, and professional broadcast monitors requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP3394SGY-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 MP3394S product line targets large-format LCD backlighting, delivering integrated step-up control, precision current regulation, and robust fault protection in a single IC to replace discrete LED driver solutions.

FAQ

What is the maximum LED string voltage supported by MP3394SGY-Z?

The MP3394SGY-Z does not define a fixed maximum LED string voltage; instead, it regulates output based on the highest forward voltage among active strings. With 28V input and typical boost efficiency (~85%), output can exceed 40V depending on inductor, diode, and capacitor selection - limited only by external MOSFET V_DS rating and OVP programming.

Can MP3394SGY-Z drive more than four LED strings?

Yes - two or more MP3394SGY-Z ICs can be cascaded: tie COMP and VCC pins together, use one IC's GATE to drive the shared boost inductor, and route LED strings across all devices. This configuration supports up to 8 strings with synchronized dimming and unified voltage regulation.

How does the MP3394SGY-Z handle a single open LED string?

When one string opens, the corresponding LEDx pin voltage drops below 196mV, triggering open-string detection. The IC marks that string OFF, continues regulating remaining strings, and maintains output voltage at the level required by the highest-voltage active string - preserving partial backlight functionality.

What is the minimum recommended DBRT input voltage for dimming control?

The DBRT pin accepts 0.2V–1.2V for DC-input PWM dimming, where 0.2V yields 0% duty cycle and 1.2V yields 100%. Voltages below 0.2V are clamped to 0%, and above 1.2V are clamped to 100%; the linear relationship enables precise analog brightness control without external DAC scaling.

Is external current-sense resistor (RSENSE) required for normal operation?

No - RSENSE is only required if using the ISENSE pin for peak-current-mode control in custom boost topologies. For standard operation, ISENSE must be tied to GND (not left floating), as the IC relies on internal current sensing through the LEDx sinks for regulation and protection.

Does MP3394SGY-Z support I²C or other digital interfaces?

No - MP3394SGY-Z uses only analog and PWM control signals (EN, DBRT, BOSC, OSC, ISET, OVP). It has no digital communication interface; brightness and protection thresholds are set entirely through external passive components and voltage levels.

What is the purpose of the NC pins in the SOIC20 package?

Pins 1, 2, 3, 4, 19, and 20 are designated NC (no connect) in the SOIC20 variant - they have no internal connection and must remain unconnected. These pins exist for package compatibility and mechanical stability, not functional expansion.