Monolithic Power Systems Inc. MP3394SGF-Z

Overview

MP3394SGF-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 MP3394SGF-Z datasheet, MP3394SGF-Z pinout, MP3394SGF-Z application, or MP3394SGF-Z equivalent, key selection considerations include its TSSOP16EP package thermal performance (θJA = 45°C/W), dual dimming modes (external PWM or DC-input burst PWM), open/short LED fault protection, cascading capability for 8+ strings, and OVP threshold programmability via resistor divider.

Technical Context

The MP3394SGF-Z employs peak-current-mode control with fixed-frequency operation, using an external MOSFET driven by a 6.8V-tolerant gate driver (4Ω sourcing / 2Ω sinking). Its internal 5.8V LDO (VCC) powers control circuitry and the gate driver, with UVLO activation at 3.9V (200mV hysteresis).

Current regulation relies on four matched internal current sources referenced to a 1.22V ISET pin voltage, enabling 32mA typical string current with ±2.5% matching. Dimming is implemented either via external PWM applied to DBRT (with BOSC grounded through 100kΩ) or DC analog voltage (0.2–1.2V) on DBRT paired with a timing capacitor on BOSC to generate internal burst PWM (1–2 kHz typical).

Key Specifications

Pinout & Package

TSSOP16EP package with exposed thermal pad (must be connected to GND for optimal thermal performance); 4.4mm × 5.0mm footprint, 1.2mm height, lead-free RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP3394SGF-Z, MPQ3394-AEC1 adds automotive qualification but offers no performance gain in standard environments, while LM3409QMY requires additional components and layout effort to achieve basic 4-string functionality - making MP3394SGF-Z the optimal choice for integrated, production-ready LCD backlight designs.

Availability

MP3394SGF-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, consistent parametric performance, and long-term manufacturing continuity.

Supply support for MP3394SGF-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 solutions.

The MP3394S product line targets large-format LCD backlighting applications, delivering integrated multi-string current regulation, robust fault protection, and flexible dimming to replace discrete solutions in display electronics.

FAQ

What is the maximum allowable LED string voltage when using MP3394SGF-Z?

The MP3394SGF-Z does not directly regulate output voltage; it controls LED current while allowing the boost converter to generate whatever voltage is needed to forward-bias the connected LED strings. The absolute maximum voltage at LED1–LED4 pins is +55V, and the OVP pin can be configured to trigger shutdown before reaching hazardous levels - typically set to 1.1–1.2× the nominal output voltage using the external resistor divider.

Can MP3394SGF-Z drive more than four LED strings?

Yes - two or more MP3394SGF-Z ICs can be cascaded in parallel using shared VCC, COMP, EN, and DIM signals, with only the master IC driving the external MOSFET. This configuration supports up to 8 or more strings while maintaining current matching and synchronized dimming, as confirmed in the datasheet's "Expanding LED Channels" section.

What is the purpose of the ISENSE pin, and can it be left unconnected?

The ISENSE pin monitors the voltage across the external current-sense resistor (RSENSE) to implement peak-current-mode control and cycle-by-cycle current limiting. It must not be left floating: for non-cascaded operation, tie ISENSE directly to GND; for cascaded configurations, connect the slave IC's ISENSE to GND while the master IC uses it for sensing.

How does open-string protection operate in MP3394SGF-Z?

When an LED string opens, its corresponding LEDx pin is pulled to GND. The IC detects this condition and marks that string as inactive after confirming the OVP pin voltage exceeds 1.23V. Remaining active strings continue regulation, and the output voltage adjusts to meet the highest-voltage string's requirement - ensuring at least one string remains lit unless all strings fail.

Is external PWM dimming compatible with the TSSOP16EP package?

Yes - external PWM dimming is fully supported on MP3394SGF-Z regardless of package. Apply the PWM signal (100Hz–20kHz, >1.2V amplitude, <0.4V low level) to the DBRT pin while grounding BOSC through a 100kΩ resistor. No package-specific limitations affect dimming functionality or timing accuracy.

What thermal derating applies to MP3394SGF-Z in TSSOP16EP at 85°C ambient?

With θJA = 45°C/W and TJ(MAX) = 150°C, the maximum allowable power dissipation at TA = 85°C is (150 − 85)/45 = 1.44W. At full load (4 × 200mA, VIN = 12V), typical power dissipation is ~0.9W - well within limit. However, ensure the exposed pad is soldered to ≥2 cm² copper area with ≥4 thermal vias to maintain safe junction temperature.