Monolithic Power Systems Inc. MP3387LGRT-P

Overview

MP3387LGRT-P from Monolithic Power Systems is a 6-string white LED driver IC with step-up DC-DC conversion, analog+PWM mixed dimming, and ±3% current matching across strings. It delivers up to 45mA per string from a 3V–26V input, regulates output up to 45V, and integrates six open-drain current sinks for LCD backlighting in notebook PCs and mid-size displays.

For engineers reviewing the MP3387LGRT-P datasheet, MP3387LGRT-P pinout, MP3387LGRT-P application, or MP3387LGRT-P equivalent, key selection criteria include its 24–27.5kHz audible-noise-free PWM dimming frequency translation, programmable OVP via resistor divider, 500mV LED current-sink regulation voltage, and TQFN-24 (4×4mm) thermal performance with θJA = 42°C/W.

Technical Context

The MP3387LGRT-P employs peak-current-mode PWM control with externally programmable switching frequency (532–1.43MHz via FREQ pin resistor). Its internal 5V LDO (VCC) powers gate drivers and logic, with UVLO hysteresis of 200mV and shutdown quiescent current of 1μA.

It implements dual-dimming architecture: when MIX pin is high (default), it switches between analog dimming (≥25% PWM duty) and scaled PWM dimming (<25%), translating 100Hz–20kHz input signals to 24–27.5kHz output to eliminate audible noise. Each LEDX pin serves as an open-drain current sink with 400–600mV regulation voltage and short/open fault detection.

Key Specifications

Pinout & Package

TQFN-24 (4mm × 4mm) package with exposed thermal pad connected to PGND; 0.5mm pitch, JEDEC MO-220 WGGD-compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar white LED driver applications.

Compared with MP3389GQ-Z and LM3409QMY/NOPB, the MP3387LGRT-P uniquely combines 6-string integration, ±3% matching, programmable dimming mode, and automatic 24–27.5kHz noise suppression-making it optimal for cost-sensitive, space-constrained LCD backlight designs demanding silent, uniform illumination.

Availability

MP3387LGRT-P is available at Aetrix Electronics and suitable for notebook PC backlighting, small LCD TV power management, and automotive infotainment display systems requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for MP3387LGRT-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 focus on efficiency, integration, and thermal robustness.

The MP3387L product line targets LCD backlight applications requiring multi-string LED current regulation, mixed dimming, and comprehensive fault protection in compact form factors.

FAQ

What is the minimum input voltage required for MP3387LGRT-P to operate?

The MP3387LGRT-P requires a minimum input voltage of 3V to enable internal circuitry and sustain regulated LED current. Below this, the EN pin UVLO prevents startup, and the internal VCC LDO cannot maintain 5V output-ensuring reliable turn-on only within its specified 3V–26V range.

How does the MIX pin affect dimming behavior?

When MIX is high (default), the IC uses combined analog+PWM dimming with a 25% transfer point: analog dimming above 25% duty reduces power loss, while PWM dimming below 25% extends dimming ratio and shifts frequency to 24–27.5kHz. Pulling MIX low disables analog dimming and forces pure PWM control.

Can MP3387LGRT-P drive more than 6 LED strings?

No-the MP3387LGRT-P integrates exactly six dedicated current-sink channels (LED1–LED6) with matched regulation. Driving additional strings would require external current mirrors or parallel ICs, compromising accuracy, thermal balance, and fault coverage. For >6 strings, consider MP3389GQ-Z (8-string) instead.

What is the purpose of the two LX pins (LX1 and LX2)?

LX1 and LX2 are paralleled drains of internal power MOSFETs, designed to reduce conduction loss and improve thermal distribution. They must be shorted externally on PCB and connected jointly to the boost inductor and rectifier-an essential layout requirement to maintain current sharing and prevent uneven switching stress.

How is over-voltage protection configured?

OVP is set using a resistor divider from V_OUT to the OVP pin, targeting 1.2V at the pin. The threshold is programmable between 1.16V and 1.24V; typical design uses 1.1–1.2× nominal V_OUT to allow margin for ripple while preventing false trips during transient load steps.

Does MP3387LGRT-P support I²C or other digital interfaces?

No-the MP3387LGRT-P uses only analog and PWM control signals (EN, PWMI, MIX, ISET, OVP) with no digital communication interface. Dimming, frequency, and protection thresholds are set entirely through external resistors and logic pins-simplifying design but requiring hardware-level configuration.

What is the maximum allowable LED string voltage drop?

Each LEDX pin supports up to 45V cathode-to-ground voltage, enabling strings with total forward voltage ≤45V. With typical white LED V_F ≈ 3.2V, this supports up to 14 LEDs in series per string while maintaining regulation margin and OVP headroom.