Monolithic Power Systems Inc. MP3385GF-P

Overview

MP3385GF-P from Monolithic Power Systems is a 4-string, 80V-rated WLED controller with I²C interface, designed for LCD panel backlighting in mid-to-large displays. It delivers up to 300mA per string with 1.8% current matching, supports 4.5–33V input, and regulates output via external MOSFET boost stage. Used in desktop monitors and all-in-one PCs for precise brightness control.

For engineers reviewing the MP3385GF-P datasheet, MP3385GF-P pinout, MP3385GF-P application, or MP3385GF-P equivalent, key selection criteria include programmable 100–900kHz switching frequency, 8-bit full-scale current tuning (2–100%), 10-bit internal dimming resolution, and cascading capability across multiple controllers sharing one power source.

Technical Context

The MP3385GF-P implements peak-current-mode PWM control for the step-up converter, using an external N-MOSFET driven by the DRV pin. Its internal 6V LDO (VCC) powers gate drive and logic, with UVLO at 4.0V (340mV hysteresis). The I²C interface (400kHz compliant) configures dimming mode, OVP threshold (18–74V), OCP level (150–500mV), and switching frequency.

Four open-drain LED current sinks (LED1–LED4) enable independent string regulation; unused strings are auto-detected at startup to prevent OVP trip. Protection includes recoverable thermal shutdown (150°C/125°C hysteresis), latch-off/recoverable OCP, LED short/open detection, and inductor/diode short sensing via IS pin.

Key Specifications

Pinout & Package

TSSOP20-EP package (4.4mm × 6.5mm, 0.65mm pitch) with exposed thermal pad connected to GND for enhanced heat dissipation in high-current backlight applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP3385GR-Z, the MP3385GF-P offers identical electrical performance but trades thermal efficiency for easier hand-soldering and rework via TSSOP leads; versus RT8542GSP, it adds full digital configurability and higher voltage margin at modest BOM cost increase.

Availability

MP3385GF-P is available at Aetrix Electronics and suitable for desktop LCD flat panel displays, all-in-one PCs, and industrial HMI displays requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for MP3385GF-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 design centers in the US, China, and Taiwan.

The MP3385 product line targets energy-efficient, digitally configurable backlight solutions for mid-to-large LCD panels - emphasizing precision current matching, thermal resilience, and seamless integration with system microcontrollers.

FAQ

What is the maximum LED string voltage the MP3385GF-P can safely regulate?

The MP3385GF-P has an absolute maximum rating of 80V per LED string, with programmable over-voltage protection (OVP) thresholds ranging from 18V to 74V in 2V steps. This allows safe operation with up to 14-series white LEDs (typical VF ≈ 5.7V) while maintaining margin against transients. The OVP threshold is set via I²C register 05H bits OVP0–OVP4 and triggers shutdown if exceeded.

How does the MP3385GF-P achieve 1.8% current matching between strings?

The 1.8% current matching is achieved through matched on-chip current sink circuitry and precision reference design, verified across process, voltage, and temperature (PVT) corners. Each LEDX output uses identical transistor sizing and biasing, with VISET reference voltage tightly controlled at 1.98V ±25mV. Matching is measured at 200mA per string and remains stable across -40°C to +125°C junction temperature.

Can the MP3385GF-P operate without an external microcontroller?

Yes - the MP3385GF-P supports standalone operation using external PWM and analog inputs. In INTERFACE=0 mode (default), brightness is controlled directly by the PWM pin, and dimming mode is selected via MODE bits set by hardwired logic or pull-up/down resistors. I²C is optional for advanced configuration like OVP threshold or cascading setup.

What is the purpose of the LPF pin, and when should its capacitor be omitted?

The LPF pin outputs a low-pass filtered version of the PWM input for analog and mixed dimming modes. A capacitor (typically 100nF–1μF) between LPF and GND sets the filter cutoff. It must be omitted in direct PWM dimming mode (MODE=00, INTERFACE=0) to prevent interference with fast PWM edge timing - leaving it connected would distort dimming response and reduce effective resolution.

Does the MP3385GF-P support daisy-chaining multiple controllers from one boost stage?

Yes - the MP3385GF-P supports cascading: one device acts as master (DRV active), while others operate as slaves (DRV disabled, IS tied to GND). All share the same inductor and Schottky diode, reducing component count and board area. Cascading requires I²C coordination to synchronize dimming and fault reporting, with slave devices configured via unique I²C addresses.

What failure modes trigger the FT (fault flag) pin, and how is recovery handled?

The FT pin goes low for OVP, OCP (latch-off mode), OTP, LED open/short, and inductor/diode short faults. Recovery depends on fault type: thermal and OCP (recoverable mode) self-clear when condition normalizes; OVP and latch-off OCP require EN toggle or VIN cycle. Fault status is latched in register 03H bits DIM0–DIM1 and cleared only by I²C write or power reset.