Monolithic Power Systems Inc. MP3373GM-Z

Overview

MP3373GM-Z from Monolithic Power Systems is an 8-channel step-up WLED controller with external transistor drive architecture, designed for large LCD panel backlighting. It operates from 9V–40V input, delivers 1.2% current matching across strings, supports programmable 100kHz–1MHz switching frequency via ROSC, and integrates open/short LED protection with fault flag output - deployed in 2D/3D TV backlight systems.

For engineers reviewing the MP3373GM-Z datasheet, MP3373GM-Z pinout, MP3373GM-Z application, or MP3373GM-Z equivalent, key selection criteria include its external MOSFET gate drive capability (10V VCC LDO), phase-shift PWM dimming (45°–90° adjustable), 200mV LED current sense threshold, CTLx-based current sink control, and TSSOP-28 package thermal performance (θJA = 80°C/W).

Technical Context

The MP3373GM-Z implements a fixed-frequency, peak-current-mode boost converter with independent 8-channel constant-current regulation using external NPN/PNP transistors controlled via CTL1–CTL8 pins. Each channel's current is set by FBx feedback (200mV typical reference) and matched to ±1.2% accuracy.

It features programmable over-voltage protection (2.5V OVP threshold, 100mV hysteresis), thermal shutdown at 150°C (25°C hysteresis), and fault reporting via open-drain FAULT pin. Phase shift timing is dynamically adjusted based on active string count (45° for 8 strings, 60° for 6, 90° for 4), reducing inrush current and audible noise.

Key Specifications

Pinout & Package

TSSOP-28 package with exposed thermal pad (θJA = 80°C/W, θJC = 30°C/W); RoHS-compliant, lead-free construction.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP3372GM-Z, the MP3373GM-Z adds two current channels and enhanced thermal robustness for larger displays; versus RT8546GQW, it trades integrated drivers for higher voltage tolerance, external transistor flexibility, and multi-IC scalability.

Availability

MP3373GM-Z is available at Aetrix Electronics and suitable for LCD TV backlighting, commercial display panels, medical imaging monitors, and industrial HMI systems requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for MP3373GM-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 design centers in the US, China, and Taiwan.

The MP3373 product line targets high-efficiency, high-precision LED backlight control for large-format displays, emphasizing current matching, fault resilience, and thermal reliability in demanding visual applications.

FAQ

What is the function of the PSEN pin on MP3373GM-Z?

The PSEN pin enables or disables the phase-shift PWM dimming feature. When left floating, it activates automatic phase shifting (45°–90° depending on active string count) to reduce input ripple and audible noise. Pulling PSEN to GND disables phase shift, synchronizing all 8 channels to the same PWM edge.

How is LED string current set on MP3373GM-Z?

Each string's current is set by the external current-sense resistor connected between the FBx pin and the emitter of the external transistor. With a 200mV internal reference, current is calculated as I_LED ≈ 200mV / R_SENSE. For example, a 2Ω resistor sets ~100mA per string. The FB pin must never be left open.

Can MP3373GM-Z operate with fewer than 8 LED strings?

Yes. Unused strings are disabled by connecting their corresponding CTLx pin to GND. During startup, the IC automatically detects grounded CTL pins and excludes those channels from the closed-loop regulation and phase-shift timing, adjusting delay accordingly (e.g., 6 active strings → 60° phase shift).

What protections does MP3373GM-Z provide for LED string faults?

It provides open-string detection via OVP monitoring and short-string detection via CTLx pin voltage thresholds. Open strings trigger OVP latching at 2.5V; shorted strings are marked off if CTLx exceeds 6V for 4096 clock cycles. Both conditions pull the FAULT pin low and disable affected channels while maintaining regulation on healthy strings.

Is MP3373GM-Z compatible with both analog and PWM dimming?

Yes. Analog dimming uses a 0.4V–1.5V DC voltage on the DIM pin to linearly scale LED current from 0% to 100%. PWM dimming accepts signals ≥1.6V high / ≤0.3V low on either EN/PWMI or DIM pins, chopping the regulated current at the applied duty cycle without affecting regulation accuracy.

What is the role of the ISENSE pin in MP3373GM-Z?

The ISENSE pin monitors inductor current for peak-current-mode control and overcurrent protection. In standard single-IC operation, it connects to the current-sense resistor between the MOSFET source and PGND. In multi-IC shared-power configurations, only the master IC uses ISENSE; slaves tie it to GND.

How does MP3373GM-Z handle thermal overload?

It integrates a die-temperature sensor that triggers thermal shutdown at 150°C. Once tripped, the IC halts switching and pulls FAULT low. Operation resumes only after die temperature falls below 125°C (25°C hysteresis), preventing repeated cycling and ensuring safe cooldown before restart.