Monolithic Power Systems Inc. MP3378GY-P

Overview

MP3378GY-P from Monolithic Power Systems is a dual-function integrated WLED backlight controller and synchronous buck converter for LCD monitor power systems. It delivers 4-channel, up to 350 mA/string constant-current LED driving with 2.5% current matching accuracy, plus a 5 V/3 A buck regulator with 144 mΩ/58 mΩ internal MOSFETs, operating from 5–24 V input. Used in desktop LCD flat-panel displays to simultaneously power LED backlights and internal logic rails.

For engineers reviewing the MP3378GY-P datasheet, MP3378GY-P pinout, MP3378GY-P application, or MP3378GY-P equivalent, key selection criteria include independent PWM/analog dimming support per string, integrated OVP/OTP/LED short-open protection, SOIC-28EP package thermal performance (θJA = 62.5°C/W), and synchronized buck switching (250 kHz–2 MHz).

Technical Context

The MP3378GY-P integrates two independent control loops: a peak-current-mode boost controller for WLED strings (programmable 150–590 kHz via OSC resistor) and a fixed-frequency (235 kHz typ.) current-mode buck converter with AAM light-load mode. Both sections share isolated ground domains (GND1/GND2/AGND) and feature separate enable, feedback, and protection inputs.

Its architecture supports simultaneous operation: the WLED section regulates cathode current via external N-MOSFET gate drive (GATE pin), while the buck section regulates output voltage via FB divider and internal HS/LS MOSFETs. Protection logic includes cycle-by-cycle ISENSE limiting (230 mV threshold), latch-off thermal shutdown (150°C), and per-string LEDX voltage monitoring for open/short detection.

Key Specifications

Pinout & Package

MP3378GY-P is housed in a 28-pin SOIC package with exposed thermal pad (SOIC-28EP), rated for 2 W continuous power dissipation at TA = 25°C (θJA = 62.5°C/W). The exposed pad must be soldered to PCB ground plane for thermal integrity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar WLED controller + buck converter applications.

Compared with MPQ3378-AEC1, MP3378GY-P offers lower cost and standard industrial qualification but lacks automotive reliability testing; versus RT8542GSP, it reduces total solution size by 35% and improves current matching by 1.0%, enabling higher-end display uniformity.

Availability

MP3378GY-P is available at Aetrix Electronics and suitable for desktop LCD flat panel displays, flat panel video displays, and 2D/3D LCD TVs requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP3378GY-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 over 20 years of expertise in DC/DC conversion and LED driver technology.

The MP3378 product line targets cost-sensitive, space-constrained LCD backlight systems requiring integrated WLED control and auxiliary power generation in a single SOIC package.

FAQ

What is the maximum input voltage supported by MP3378GY-P?

The MP3378GY-P supports up to 24 V on VIN1 (WLED section) and VIN2 (buck section), with absolute maximum ratings of 28 V. Operation above 24 V risks exceeding recommended conditions and may trigger OVP or UVLO protection.

How does the AAM pin affect buck converter efficiency?

The AAM pin sets the threshold for entering pulse-frequency modulation (PFM) mode. When COMP_BUCK falls below the AAM voltage (set by external resistor), the controller skips switching cycles, reducing quiescent current to 200 µA and improving light-load efficiency by up to 15% at 100 mA output.

Can MP3378GY-P drive more than 4 LED strings?

No. The device has exactly four dedicated open-drain LEDX outputs (LED1–LED4) and associated current-sense circuitry. Driving additional strings would require external multiplexing or a second MP3378GY-P, as no internal channel expansion capability exists.

What is the purpose of the exposed pad on the SOIC-28EP package?

The exposed thermal pad must be soldered to a solid PCB ground plane to dissipate heat. It reduces θJA from 62.5°C/W to approximately 45°C/W in typical layouts, enabling safe operation at 1.8 W dissipation without forced airflow.

How is LED current matching accuracy achieved?

Matching is achieved through laser-trimmed internal references and matched current-sense amplifier paths. At 32 mA per string, the ±2.5% specification means the difference between highest and lowest string current is ≤1.6 mA, verified across process, voltage, and temperature.

Does MP3378GY-P support I²C or other digital interfaces?

No. All configuration is analog: LED current via ISET resistor, dimming via ADIM/PWM voltage levels, OVP threshold via resistor divider on OVP pin, and buck output via FB divider. No digital communication interface is integrated.

What happens during an LED open-circuit fault?

When an LED string opens, its LEDX pin voltage drops below 190 mV. After >4 µs, the controller marks that string as faulty, disables its dimming switch, and continues regulating remaining strings using the highest-voltage LEDX as feedback reference to maintain output stability.