Monolithic Power Systems Inc. MP3394SGS-P

Overview

MP3394SGS-P 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. It drives an external N-MOSFET to boost output voltage and regulates LED current using internal current sources with 300mV regulation voltage.

For engineers reviewing the MP3394SGS-P datasheet, MP3394SGS-P pinout, MP3394SGS-P application, or MP3394SGS-P equivalent, key selection criteria include its 4-string WLED architecture, DC/PWM dimming flexibility, open/short LED protection, cascading capability for expanded channel count, and SOIC16 package thermal performance (θJA = 80°C/W).

Technical Context

The MP3394SGS-P employs peak-current-mode control with fixed-frequency operation, where switching frequency is set by an external resistor on the OSC pin (140–670 kHz range). Its internal error amplifier compares ISET pin voltage (regulated at 1.22V) against a reference to control LED current via four matched current sinks.

Dimming is implemented via two modes: external PWM applied to DBRT pin (with BOSC grounded), or DC analog input (0.2–1.2V) on DBRT with BOSC capacitor setting internal dimming frequency (1–2 kHz typical). Protection includes OVP (1.23V threshold), LED open/short detection (196mV UVLO / 6.1V OV threshold), and thermal shutdown at 150°C.

Key Specifications

Pinout & Package

MP3394SGS-P is housed in a SOIC16 package (10.3mm × 6.1mm, 1.27mm pitch) with exposed pad connected to GND for thermal enhancement. Pin 1 is marked with dot; pin numbering follows standard SOIC convention.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP3394SGS-P, the MP3394SGF-P offers superior thermal performance in compact layouts, while the MPQ3394-AEC1 adds automotive qualification at the expense of cost and availability - neither is pin-compatible without PCB redesign due to differing package footprints and qualification-specific test limits.

Availability

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

Supply support for MP3394SGS-P 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, flexible dimming, and robust fault protection in compact packages.

FAQ

What is the maximum total output power supported by MP3394SGS-P?

The MP3394SGS-P does not specify a fixed maximum output power, but its 200mA/string limit across 4 strings and 28V max output implies up to 22.4W (4 × 200mA × 28V) under ideal conditions. Real-world power is constrained by thermal limits: SOIC16 package dissipation is capped at 1.56W at 25°C ambient, requiring careful thermal design to sustain high-output operation.

Can MP3394SGS-P drive more than 4 LED strings?

Yes - MP3394SGS-P supports cascading: two or more units can operate in parallel from a single boost inductor and output capacitor. The master unit drives the MOSFET and regulates COMP voltage; slave units connect COMP, EN, and DIM lines to the master while grounding their ISENSE pins. This expands capacity to 8+ strings without additional inductors.

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

The DBRT pin requires ≥0.2V to initiate dimming; below this, output is fully off. For linear dimming, 0.2V yields 0% duty cycle and 1.2V yields 100%. Input below 0.2V risks undefined behavior - ensure DAC or microcontroller output has rail-to-rail capability and noise immunity to avoid unintended blanking.

How does open-string protection behave when only one LED string fails?

When one string opens, its LEDX pin voltage drops below 196mV, triggering automatic disable of that channel. The remaining three strings continue operating at full current, and the output voltage self-adjusts to the highest forward voltage among active strings - ensuring uninterrupted backlighting with minimal luminance reduction.

Is external MOSFET selection critical for short-circuit protection?

Yes - the MP3394SGS-P's LEDX pins tolerate only up to 6.1V. If output voltage exceeds this (e.g., >24V with 4× LEDs), external N-MOSFETs must be added per string to isolate the IC from overvoltage stress during short events. MPS recommends selecting MOSFETs with VDS > 1.5× VOUT and RDS(ON) < 100mΩ for minimal conduction loss.

Does MP3394SGS-P support analog (current) dimming in addition to PWM?

No - MP3394SGS-P supports only PWM-based dimming: either externally generated PWM applied to DBRT, or internally generated burst PWM controlled by a DC voltage on DBRT. It does not provide analog current scaling; LED current magnitude is fixed by the ISET resistor, and brightness is varied solely via duty cycle modulation.

What is the purpose of the ISENSE pin in non-cascaded operation?

In standalone operation, the ISENSE pin must be tied to GND - leaving it floating violates absolute maximum ratings and may cause erratic switching or damage. It is only used in cascaded configurations to synchronize current limiting between master and slave ICs; no external component connects to it unless implementing multi-IC boost sharing.