Monolithic Power Systems Inc. MP3398EGF-P

Overview

MP3398EGF-P from Monolithic Power Systems is a 4-string, step-up WLED controller with peak-current mode control, programmable switching frequency (305–460 kHz), 4.5V–33V input range, and 80V absolute string rating. It delivers up to 400mA per string with 2.3% current matching accuracy and supports direct PWM and analog dimming via ADIM/PWM pins for large LCD panel backlighting in desktop monitors and all-in-one PCs.

For engineers reviewing the MP3398EGF-P datasheet, MP3398EGF-P pinout, MP3398EGF-P application, or MP3398EGF-P equivalent, key selection criteria include its TSSOP-16EP package thermal performance (θJA = 45°C/W), 202mV cycle-by-cycle current limit threshold, cascading capability for 8+ LED strings, and integrated open/short-string protection with 130°C latch-off thermal shutdown.

Technical Context

The MP3398EGF-P implements fixed-frequency peak-current mode control using an external ROSC resistor to set switching frequency between 305–460 kHz. Its internal 5.9V LDO (VCC) powers gate drivers and logic, with UVLO at 4.0V (350mV hysteresis) and EN logic thresholds at 1.5V (high) and 0.6V (low).

Four independent open-drain LEDX outputs drive cathodes of WLED strings, each regulated by internal current sources achieving 2.3% matching at 200mA. Protection includes programmable OVP (1.9–2.1V reference), LEDX UVLO (200mV), short-inductor/diode detection (8-cycle latch), and OTP at 130°C.

Key Specifications

Pinout & Package

TSSOP-16EP package with exposed thermal pad (θJA = 45°C/W, θJC = 10°C/W); 4.4mm × 5.0mm footprint, 1.2mm height, RoHS-compliant lead-free finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPQ3398-AEC1, the MP3398EGF-P lacks automotive qualification but matches all electrical and thermal specs for commercial displays; versus LM3409QMH/NOPB, it integrates four channels and current matching, reducing BOM count and PCB area by >60%.

Availability

MP3398EGF-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 lifecycle support, and RoHS-compliant packaging.

Supply support for MP3398EGF-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 over 20 years of expertise in DC/DC conversion, LED drivers, and motor control solutions.

The MP3398E product line targets large-format LCD backlighting applications, delivering high-efficiency, multi-string WLED control with integrated protection and dimming flexibility for commercial and industrial displays.

FAQ

What is the maximum number of LED strings supported by MP3398EGF-P in a single IC?

The MP3398EGF-P supports exactly four independent LED strings via its LED1–LED4 pins. Each string is driven by a dedicated open-drain current sink with internal regulation. Cascading two or more ICs allows expansion to eight or more strings while sharing one boost converter and COMP node.

How does the MP3398EGF-P handle open-string faults?

When an LED string opens, the corresponding LEDX pin voltage drops below 200mV, triggering open-string detection. The IC marks off that string, continues regulating remaining strings, and maintains output voltage via the highest-voltage active LEDX pin. If all strings open, the boost converter shuts down.

Can MP3398EGF-P operate with input voltages below 4.5V?

No. The absolute minimum input voltage is 4.5V per datasheet specifications. Below this, the internal VCC LDO cannot sustain 5.9V output, causing UVLO lockout and disabling gate drive and control logic. Input must remain ≥4.5V for functional operation.

What is the purpose of the ISENSE pin, and what happens if it's left floating?

The ISENSE pin monitors voltage across the external current-sense resistor for peak-current-mode control and cycle-by-cycle overcurrent protection. Leaving it floating violates the datasheet requirement and may cause erratic switching, failed OCP response, or latch-off due to undefined comparator input-always tie to GND or the sense resistor.

Does MP3398EGF-P support analog dimming without an external PWM signal?

No. Analog dimming requires a PWM signal applied to the ADIM pin. An internal 10MΩ/100pF RC filter converts the PWM into a DC voltage proportional to duty cycle. No true DC analog voltage input is supported; the ADIM pin expects a ≥20kHz PWM waveform for accurate filtering.

What thermal derating applies to MP3398EGF-P in TSSOP-16EP package at 85°C ambient?

With θJA = 45°C/W, junction temperature rise at 2.78W dissipation is 125°C, exceeding the 150°C max. At 85°C ambient, max allowable power is (150−85)/45 = 1.44W. Derate linearly above 25°C ambient using the 45°C/W slope to avoid thermal shutdown.

Is the OSC pin compatible with capacitive loading for frequency tuning?

No. The OSC pin requires only an external resistor to GND for frequency setting; capacitive loading disrupts the internal current-source oscillator and causes frequency instability or startup failure. Do not add capacitors or other reactive elements to the OSC node.