Monolithic Power Systems Inc. MP3398AGF-P

Overview

MP3398AGF-P 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 LED current via external ISET resistor (VISET = 1.22V). Used in flat-panel TVs and monitors where precise brightness control and multi-string reliability are critical.

For engineers reviewing the MP3398AGF-P datasheet, MP3398AGF-P pinout, MP3398AGF-P application, or MP3398AGF-P equivalent, key selection criteria include its TSSOP16-EP package thermal performance (θJA = 45°C/W), dual-dimming flexibility (ADIM/PWM pins), OVP/OTP/LED open-short protection, and cascading capability using shared inductive power sources.

Technical Context

The MP3398AGF-P implements peak-current-mode control with fixed-frequency switching (programmable 150–621 kHz via OSC resistor) and internal 6V LDO (VCC) for gate driver and logic supply. It uses four matched internal current sinks (LED1–LED4) referenced to 1.22V at ISET to achieve 2.5% inter-string current regulation.

Protection architecture includes recoverable thermal shutdown (TST = 150°C, 25°C hysteresis), latch-off LED short detection (4096 cycles at >6.3V on LEDX), and programmable over-voltage protection (OVP threshold set via resistor divider to 1.23V on OVP pin).

Key Specifications

Pinout & Package

MP3398AGF-P is housed in a thermally enhanced TSSOP16-EP package with exposed pad tied to GND for improved heat dissipation (θJC = 10°C/W, θJA = 45°C/W). The 16-pin layout supports compact, high-power-density 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, the MP3398AGF-P offers superior thermal management via its exposed-pad TSSOP package-critical for sustained 350mA/string operation-while MPQ3398-AEC1 adds automotive qualification at the expense of cost and availability, making MP3398AGF-P the optimal choice for industrial and consumer display applications demanding performance and supply stability.

Availability

MP3398AGF-P is available at Aetrix Electronics and suitable for desktop LCD flat panel displays, 2D/3D LCD TVs, and industrial human-machine interfaces requiring stable component supply, consistent parametric performance, and long-term production continuity.

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

The MP3398A product line targets large-format LCD backlighting, delivering high-efficiency, multi-string LED control with integrated protection and flexible dimming-designed specifically for display manufacturers needing reliable, scalable, and thermally optimized solutions.

FAQ

What is the maximum allowable LED string voltage when using MP3398AGF-P?

The MP3398AGF-P does not impose a fixed maximum LED string voltage; instead, it regulates output based on the highest forward voltage among active strings. Its OVP threshold is programmable up to ~60V (via resistor divider), and absolute maximum rating for LEDX pins is +55V. Practical limit depends on external MOSFET VDS rating and boost diode selection-typically configured for 30–45V output in 4-string TV applications.

Can MP3398AGF-P drive more than 4 LED strings?

Yes-MP3398AGF-P supports cascading: two or more ICs can share a single inductive power source and output rail. Each IC independently regulates its 4 strings, while current matching remains within ±2.5% per device. This enables 8-, 12-, or 16-string configurations without sacrificing regulation accuracy or adding complex master-slave signaling.

How does the ADIM pin handle PWM versus DC input signals?

The ADIM pin accepts both: for DC input (0.4–1.5V), LED current scales linearly from 0% to 100%; for PWM input, an internal 10MΩ/100pF RC filter converts it to a DC-equivalent voltage-requiring ≥20kHz frequency to avoid ripple and ensure accurate dimming. If unused, ADIM must be pulled above 1.54V to disable analog dimming.

What happens during an LED open-string fault?

When an LED string opens, its corresponding LEDX pin voltage drops below 196mV. After OVP timeout (>4µs), the IC marks that string as faulty, disables its current sink, and continues regulating remaining strings using the highest active LEDX voltage as feedback reference-ensuring uninterrupted backlight operation with reduced total current.

Is external compensation required on the COMP pin?

Yes-COMP requires an external ceramic capacitor (typically 1nF–10nF) from COMP to GND to stabilize the voltage-mode feedback loop. Some designs add a series RC network for phase margin tuning. Leaving COMP unconnected causes instability, oscillation, or failure to regulate; the capacitor value directly affects transient response and loop bandwidth.

Does MP3398AGF-P support synchronous rectification?

No-MP3398AGF-P drives only the high-side N-channel MOSFET switch (via GATE pin) and relies on an external Schottky diode for the boost rectifier path. It does not provide a second gate driver or control logic for synchronous rectification; efficiency optimization must therefore focus on diode selection (low VF, fast recovery) and MOSFET RDS(ON).

What is the minimum recommended ISET resistor value?

The minimum ISET resistor is determined by max current (350mA) and VISET (1.22V): RMIN ≈ 1.22V / 0.35A = 3.49kΩ. However, MPS recommends ≥4.7kΩ to maintain accuracy under temperature drift and noise. Values below 3kΩ risk exceeding internal current-sink capability and degrading regulation precision.