Monolithic Power Systems Inc. MP3398AGF-Z

Overview

MP3398AGF-Z from Monolithic Power Systems is a 4-string white LED step-up controller with analog and PWM dimming, designed for large LCD panel backlighting. It delivers up to 350mA per string, achieves ±2.5% current matching between strings, supports 5V–28V input, and regulates output via external MOSFET switching at programmable frequencies (150–621 kHz). Used in flat-panel TV and monitor backlight systems.

For engineers reviewing the MP3398AGF-Z datasheet, MP3398AGF-Z pinout, MP3398AGF-Z application, or MP3398AGF-Z equivalent, key selection criteria include its dual-dimming capability, cascading support across multiple ICs sharing one boost stage, integrated OVP/OTP/UVP/LED open-short protection, and TSSOP16-EP thermal performance (θJA = 45°C/W).

Technical Context

The MP3398AGF-Z implements peak-current-mode control with fixed-frequency operation set by an external resistor on the OSC pin (1.23V regulated reference). Its internal 6V LDO (VCC) powers gate drive and logic, with UVLO hysteresis of 200mV and soft-start enabled on EN assertion.

Four independent current sources regulate LED string currents using ISET-resistor programming (1.22V reference), while open-drain LEDx pins enable per-string dimming control. Protection includes latch-off OVP (1.23V threshold), recoverable thermal shutdown (150°C trip, 25°C hysteresis), and 4096-cycle short-string detection based on LEDx voltage >6.3V.

Key Specifications

Pinout & Package

TSSOP16-EP package with exposed thermal pad (connected to GND), optimized for thermal dissipation (θJA = 45°C/W, θJC = 10°C/W) in space-constrained backlight designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP3398AGS-Z and MP3398AGY-Z, the MP3398AGF-Z offers superior thermal management in compact form factor, making it optimal for space-constrained, high-current backlight modules where sustained 350mA/string operation is required without heatsinking.

Availability

MP3398AGF-Z 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 manufacturing.

Supply support for MP3398AGF-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 power management ICs, with design centers in the US, China, and Taiwan.

The MP3398A product line targets large-format LCD backlighting, delivering high-efficiency, multi-string LED control with integrated protection and flexible dimming for consumer and industrial displays.

FAQ

What is the maximum LED string voltage supported by MP3398AGF-Z?

The MP3398AGF-Z does not define a fixed maximum string voltage; instead, it regulates based on the highest forward voltage among the four strings. The boost output is limited by the OVP threshold set via the OVP pin resistor divider, with typical maximum bus voltage reaching up to 55V (per absolute max rating for V_LED1–4). System-level limit depends on external MOSFET V_DS(max) and diode rating.

Can MP3398AGF-Z operate with only two LED strings connected?

Yes - the MP3398AGF-Z automatically detects active strings via LEDx pin voltages and regulates only the connected strings. Unused LEDx pins must be left unconnected (not tied high/low); the IC maintains current matching and protection functionality across active channels without modification.

How is the switching frequency calculated from the OSC resistor value?

The switching frequency is calculated using f_SW(kHz) = 67320 / R_OSC(kΩ). For example, a 374kΩ resistor yields 180kHz (67320 ÷ 374 ≈ 180). The OSC pin maintains a regulated 1.23V, so the resistor sets current into the oscillator, directly determining frequency.

Does MP3398AGF-Z support I²C or SPI interface for digital dimming control?

No - the MP3398AGF-Z provides only analog (DC voltage or filtered PWM on ADIM) and direct PWM (on PWM pin) dimming interfaces. It lacks any digital communication interface; brightness control is implemented entirely through voltage-level or pulse-width signals.

What happens during an LED open-circuit fault on one string?

When an LED string opens, its corresponding LEDx pin voltage drops below 196mV. The IC marks that string as faulty, disables its current path, and continues regulating the remaining strings. Output voltage rises until OVP triggers (if no other strings remain), then latches off after 4µs OVP violation.

Is the VCC pin intended for external load connection?

No - VCC is an internal 6V LDO output solely for powering the IC's gate driver and internal circuitry. It is rated for ≤10mA continuous load and must be bypassed with a ceramic capacitor to GND; connecting external loads risks regulation failure and thermal overstress.

How does the MP3398AGF-Z handle inductor short-circuit faults?

It uses dual detection: (1) COMP voltage clamping above threshold for >512 cycles indicates loss of output energy; (2) ISENSE voltage exceeding 720mV for 4 consecutive cycles triggers immediate latch-off. Both methods protect the external MOSFET and IC from destructive current surge.