Monolithic Power Systems Inc. MP3398BGF-P

Overview

MP3398BGF-P from Monolithic Power Systems is a 4-string white LED step-up controller with analog and PWM dimming support, designed for large LCD panel backlighting. It delivers up to 350mA per string, achieves ±2.5% current matching between strings, operates from 5V–28V input, and regulates LED current via external ISET resistor (1.22V reference). Used in desktop monitors and 2D/3D TVs where precise multi-string current balance and dual-dimming flexibility are required.

For engineers reviewing the MP3398BGF-P datasheet, MP3398BGF-P pinout, MP3398BGF-P application, or MP3398BGF-P equivalent, this page provides verified technical context on its peak-current-mode boost architecture, cascading capability with shared inductive source, OVP/OTP/UVP/LED short-open protection, and TSSOP16-EP thermal performance (θJA = 45°C/W).

Technical Context

The MP3398BGF-P implements fixed-frequency peak-current-mode control with programmable switching frequency (150–621 kHz) set by an external resistor on the OSC pin. Its internal 6V LDO (VCC) powers gate driver and logic, with UVLO at 4.0V (200mV hysteresis) and recoverable thermal shutdown at 150°C (25°C hysteresis).

It integrates four matched current sinks (LED1–LED4) with 800mV regulation voltage at 330mA, enabling tight string current matching (2.5% max deviation). Protection includes latch-off overcurrent (VLMT = 640mV), LED open/short detection (OVP threshold = 1.23V, LEDX_OV = 6.3V), and inductor/diode short detection via ISENSE blanking and cycle-by-cycle limiting.

Key Specifications

Pinout & Package

TSSOP16-EP package with exposed pad thermally connected to GND; 16-pin surface-mount footprint optimized for thermal management in high-current LED driver applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP3398AGF-P, the MP3398BGF-P offers improved thermal hysteresis consistency and enhanced OVP tolerance margin; versus RT9397BF, it delivers +33% string count, +133% per-string current, and integrated cascading-making it the sole fit for large-panel, high-luminance backlight systems.

Availability

MP3398BGF-P is available at Aetrix Electronics and suitable for desktop LCD flat panel displays, 2D/3D LCD TVs, and flat panel video displays requiring stable component supply, long-term lifecycle continuity, and RoHS-compliant packaging.

Supply support for MP3398BGF-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, and global manufacturing partnerships.

The MP3398B series belongs to MPS's LED backlight controller product line, engineered specifically for large-format LCD panel backlighting with emphasis on current matching accuracy, dual-dimming flexibility, and robust fault protection in high-reliability display systems.

FAQ

What is the minimum recommended ISET resistor value for MP3398BGF-P?

The ISET pin regulates current using a 1.22V reference. Minimum resistor is determined by max current: R_MIN = 1.22V / 0.35A ≈ 3.49kΩ. MPS recommends ≥4.7kΩ for thermal margin and noise immunity. Values below 3kΩ risk exceeding internal current sink capability and degrading matching accuracy.

Can MP3398BGF-P drive LED strings with different forward voltages?

Yes. The IC automatically selects the highest active LEDX pin voltage to regulate the boost output, ensuring sufficient headroom for all strings. If one string has significantly higher V_F, the others operate in saturation but retain current regulation accuracy within ±2.5% due to internal current-source matching.

How does the OVP protection interact with open-string faults?

During open-string fault, the affected LEDX pin pulls low, causing the boost output to rise until the OVP pin reaches 1.23V. After >4μs, the IC disables switching and marks that string. Remaining strings continue regulation using the next-highest LEDX voltage, maintaining partial backlight operation.

Is the ADIM pin compatible with microcontroller GPIO outputs?

Yes - ADIM accepts DC voltages from 0.4V to 1.5V for linear dimming, matching typical MCU DAC or filtered PWM output ranges. For PWM input, ensure frequency >20kHz and amplitude >1.5V high / <0.4V low to leverage internal RC filtering and avoid unintended dimming steps.

What is the maximum allowable voltage on the LED1–LED4 pins?

Per Absolute Maximum Ratings, LED1–LED4 tolerate −1V to +55V. In normal operation, voltage equals LED string forward drop (typically 20–40V for 6–10 LEDs). During open-fault conditions, voltage rises to OVP threshold (e.g., ~60V) before shutdown - staying within safe operating area.

Does MP3398BGF-P support spread-spectrum frequency modulation?

No. The MP3398BGF-P uses fixed-frequency peak-current-mode control with resistor-programmed oscillator. Spread-spectrum is not implemented; EMI reduction relies on optimized PCB layout, input/output capacitor selection, and selectable switching frequency (150–621 kHz) to avoid sensitive bands.

How is thermal performance affected by the exposed pad connection?

The TSSOP16-EP exposed pad must be soldered to a solid GND copper pour. With 4-layer PCB per JESD51-7, θJA = 45°C/W is achieved. Omitting thermal vias or undersized pad increases θJA to >60°C/W, risking thermal shutdown at >2.2W dissipation - well below the rated 2.78W.