Monolithic Power Systems Inc. MP3398EGS-Z

Overview

MP3398EGS-Z from Monolithic Power Systems is a 4-string, step-up WLED controller with 400mA/string current capability, 80V absolute string rating, and peak-current-mode control. It drives white LED arrays for large LCD backlighting using an external N-channel MOSFET, regulates string current via ISET resistor (2.0V reference), and achieves 2.3% inter-string current matching. Used in desktop monitors and all-in-one PCs requiring high-voltage, multi-string LED biasing.

For engineers reviewing the MP3398EGS-Z datasheet, MP3398EGS-Z pinout, MP3398EGS-Z application, or MP3398EGS-Z equivalent, key selection criteria include its 4.5–33V input range, programmable 305–460kHz switching frequency, direct PWM/ADIM dimming support, cascading capability for >4 strings, and integrated OVP/OCP/OTP/LED open-short protection.

Technical Context

The MP3398EGS-Z implements fixed-frequency peak-current-mode control with cycle-by-cycle current limiting at 202mV on ISENSE, enabling stable regulation across varying LED forward voltages up to 80V per string. Its internal 5.9V LDO powers gate drive and logic, with UVLO hysteresis of 350mV and thermal shutdown at 130°C.

It supports dual dimming: direct PWM on PWM pin (chopping I_LED = I_SET × D_DIM) and analog dimming via ADIM pin with integrated 10MΩ/100pF RC filter. Cascading uses COMP and ISENSE tie-offs between master/slave ICs sharing one boost stage.

Key Specifications

Pinout & Package

MP3398EGS-Z is packaged in SOIC-16 with exposed pad (SOIC16 per ordering table), featuring 16 pins in standard SOIC footprint with GND-connected thermal pad for enhanced thermal 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 RT8532GQW and LM3409QMY/NOPB, MP3398EGS-Z uniquely delivers 4-string integration, 80V string tolerance, and <2.3% current matching in SOIC-16EP - making it optimal for large-panel, high-reliability LCD backlight systems where string count, voltage margin, and brightness uniformity are critical.

Availability

MP3398EGS-Z is available at Aetrix Electronics and suitable for desktop LCD monitors, all-in-one PCs, and commercial digital signage requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP3398EGS-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 MP3398E product line targets large-format LCD backlighting, delivering integrated step-up control, multi-string current regulation, and comprehensive fault protection in industry-standard packages.

FAQ

What is the function of the ISENSE pin on MP3398EGS-Z?

The ISENSE pin monitors the voltage across the external current-sense resistor (RSENSE) to implement peak-current-mode control and cycle-by-cycle overcurrent protection. During normal operation, it feeds the current error signal to the PWM comparator; during cascading, the slave IC's ISENSE must be tied to GND to disable its current sensing.

Can MP3398EGS-Z drive more than four LED strings?

Yes - two or more MP3398EGS-Z ICs can be cascaded using COMP and VCC pin connections to drive up to eight or more strings while sharing a single boost converter. The master IC controls switching; slave ICs provide only current regulation and dimming control without active gate drive.

How does the ADIM pin differ from the PWM pin in dimming operation?

The ADIM pin accepts a PWM signal (≥20kHz) that is internally filtered by a 10MΩ/100pF RC network to produce a DC voltage controlling LED current amplitude. The PWM pin directly chops the LED current at the applied duty cycle without filtering - enabling higher-frequency, flicker-free dimming but requiring clean external signal routing.

What is the purpose of the OVP pin, and how is it configured?

The OVP pin sets the overvoltage protection threshold using a resistor divider from the boost output to GND. When the sensed voltage exceeds the internal 2.0V reference, the IC disables switching to protect LEDs and components during open-string faults. The recommended setting is 1.1–1.2× normal output voltage.

Does MP3398EGS-Z require an external Schottky diode, and what are its voltage requirements?

Yes - an external Schottky diode is required in the boost path. Its reverse voltage rating must exceed the maximum expected output voltage (e.g., >80V for worst-case string open condition), and its forward current rating must handle peak inductor current. Low forward voltage (VF < 0.5V) and fast recovery are essential for efficiency.

What thermal considerations apply to the SOIC-16EP package of MP3398EGS-Z?

The SOIC-16EP package has θJA = 80°C/W and θJC = 35°C/W. With 1.56W max power dissipation at TA = 25°C, PCB layout must include adequate copper area under the exposed pad, connected to GND, and thermal vias to inner/secondary ground planes to maintain TJ < 125°C in continuous operation.

Is MP3398EGS-Z compatible with both ceramic and electrolytic output capacitors?

Yes - the datasheet recommends a 4.7μF X7R ceramic capacitor in parallel with a 22–47μF electrolytic capacitor at the output. The ceramic provides low-ESR high-frequency ripple suppression, while the electrolytic handles bulk energy storage and low-frequency stability; both are necessary for loop stability and EMI compliance.