Monolithic Power Systems Inc. MP3398EGS-P

Overview

MP3398EGS-P from Monolithic Power Systems is a 4-string step-up WLED controller with peak-current mode control, 4.5V–33V input range, 80V absolute string rating, 2.3% inter-string current matching, and programmable 305–460kHz switching frequency via external resistor. It drives external N-channel MOSFETs to regulate up to 400mA per string for large LCD panel backlighting.

For engineers reviewing the MP3398EGS-P datasheet, MP3398EGS-P pinout, MP3398EGS-P application, or MP3398EGS-P equivalent, key selection criteria include its 4-channel independent current regulation, cascading capability for >4 strings, dual PWM/analog dimming support, and integrated protections including OVP, OTP, LED open/short detection, and cycle-by-cycle current limiting.

Technical Context

The MP3398EGS-P implements fixed-frequency peak-current mode control with an internal 5.9V LDO (VCC) powering gate driver and logic. Its four open-drain LEDX outputs each sink up to 400mA with 430mV typical regulation voltage at 200mA, minimizing conduction loss. The COMP pin provides error amplifier output for loop compensation using external RC networks.

Dimming is supported via two dedicated inputs: PWM pin enables direct current chopping with duty-cycle proportional average current, while ADIM accepts filtered PWM (≥20kHz) for analog amplitude control using an integrated 10MΩ/100pF RC filter. Cascading uses shared COMP and tied VCC between master/slave ICs, with slave ISENSE grounded.

Key Specifications

Pinout & Package

MP3398EGS-P is supplied in SOIC-16 package with exposed pad (SOIC16 per ordering table), featuring 16 pins with GND-referenced signal layout optimized for boost converter stability and thermal dissipation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 4-channel WLED controller applications.

Compared with RTQ2133-GQW and LM3409QMYX/NOPB, MP3398EGS-P uniquely delivers 4-channel integration with cascading, 80V string tolerance, and dual dimming-reducing component count by ≥30% and enabling scalable backlight architectures without redesign.

Availability

MP3398EGS-P is available at Aetrix Electronics and suitable for desktop LCD flat panel displays, all-in-one PCs, and 2D/3D LCD TVs requiring stable component supply, long-term production continuity, and RoHS-compliant packaging.

Supply support for MP3398EGS-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 core expertise in DC/DC conversion, LED drivers, and motor control.

The MP3398E product line targets large-format LCD backlighting, delivering high-efficiency, multi-string WLED control with robust fault protection and flexible dimming for commercial and consumer display systems.

FAQ

What is the maximum number of LED strings supported by MP3398EGS-P in a single IC?

MP3398EGS-P supports exactly four independent LED strings via its LED1–LED4 open-drain outputs. Each string is regulated to the same current set by the ISET resistor, with 2.3% matching accuracy between strings. Cascading with additional MP3398E ICs enables expansion beyond four strings using shared COMP and VCC connections.

Can MP3398EGS-P operate with an input voltage below 4.5V?

No. The absolute minimum input voltage is 4.5V per the Recommended Operating Conditions table. Below this, the internal 5.9V LDO (VCC) cannot regulate, causing UVLO lockout and disabling the controller. The VCC UVLO rising threshold is 3.7–4.3V, but VIN must remain ≥4.5V to sustain operation and meet specified current regulation accuracy.

How does the MP3398EGS-P handle an open LED string fault?

When an LED string opens, the corresponding LEDX pin voltage drops below 200mV. The IC detects this within milliseconds, marks the faulty string as disabled, and continues regulating the remaining strings. Output voltage rises until OVP threshold is reached, then switching halts. Recovery requires power cycle or EN toggle - no automatic retry to prevent repeated stress.

Is external compensation required on the COMP pin?

Yes. COMP is the error amplifier output and must be connected to GND via an RC network (e.g., 10kΩ + 1nF) to stabilize the control loop. Omitting compensation causes oscillation or poor transient response. The exact values depend on output capacitance, inductance, and desired phase margin - refer to MPS AN-107 for design guidelines.

What is the purpose of the ISENSE pin in normal operation versus cascading mode?

In normal single-IC operation, ISENSE monitors the voltage across the external current-sense resistor for peak-current-mode control and cycle-by-cycle limiting. In cascading mode, the slave IC's ISENSE must be tied to GND to disable its current sensing, allowing the master IC to control the shared boost stage while slave ICs only regulate their respective LED strings.

Does MP3398EGS-P support analog dimming without an external filter?

Yes. MP3398EGS-P integrates a 10MΩ resistor and 100pF capacitor on the ADIM pin, forming a first-order RC filter that converts incoming PWM signals (≥20kHz) into a DC control voltage. No external components are required for basic analog dimming - though higher-frequency PWM improves filtering fidelity and reduces residual ripple.

What thermal derating applies to the SOIC-16 package at 85°C ambient?

With θ_JA = 80°C/W, the maximum allowable power dissipation at T_A = 85°C is (150°C − 85°C) / 80°C/W = 0.81W. This limits continuous operation under high-current/high-V_OUT conditions. For sustained 400mA/string operation, forced air or copper pour is recommended to maintain junction temperature ≤125°C.