Monolithic Power Systems Inc. MP3393EY-LF

Overview

MP3393EY-LF from Monolithic Power Systems is an 8-channel step-up white LED driver controller with external NMOS gate drive and PNP transistor current regulation, designed for large-panel LCD backlighting. It operates from 9V–32V input, delivers up to 300mA per string with 1.2% inter-string current matching, and uses fixed-frequency peak-current-mode control with programmable switching frequency (120–160 kHz). Its 202mV FB regulation voltage minimizes power loss in high-current LED arrays.

For engineers reviewing the MP3393EY-LF datasheet, MP3393EY-LF pinout, MP3393EY-LF application in LCD TV backlighting, or MP3393EY-LF equivalent for multi-string WLED control, this page provides verified technical context, real-world dimming interface behavior, fault flag signaling logic, thermal shutdown thresholds, and daisy-chain expansion capability - all confirmed from Monolithic Power's Rev. 1.05 datasheet.

Technical Context

The MP3393EY-LF implements a peak-current-mode step-up controller with internal 10V LDO (VCC) powering gate drivers and analog circuitry, and uses an external NMOS switch driven by the GATE pin. Each of its eight CTLx pins sinks up to 13.5mA to bias external PNP transistors, while corresponding FBx pins sense 202mV ±7mV reference voltage across external current-sense resistors.

It integrates open/short LED protection via CTLx voltage monitoring (UVLO at 210mV, OV at 6.4V), OVP threshold set by resistor divider on OVP pin (1.23V trip), and fault reporting through open-drain VFAULT and FF pins. Daisy-chaining is supported via COMP and VCC pin tying between master/slave ICs without requiring additional power stages.

Key Specifications

Pinout & Package

MP3393EY-LF is packaged in SOIC28 (300 mil width) with exposed pad connected to GND for thermal performance. Pin functions are validated per Monolithic Power's Rev. 1.05 datasheet, Figure 1 and Pin Functions table (pp. 6–7).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-channel WLED step-up controller applications.

Compared with MP3393EY-LF, MPQ3393-AEC1 adds automotive qualification without altering functionality, while RT9397B trades external FET flexibility and expandability for integration - making MP3393EY-LF optimal for industrial/TV designs needing scalability and 32V headroom.

Availability

MP3393EY-LF is available at Aetrix Electronics and suitable for LCD TV backlighting, large-monitor direct-lit panels, and medical imaging display applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP3393EY-LF 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 mixed-signal ICs for power management, LED lighting, and motor control.

The MP3393 product line targets large-format LCD backlighting with scalable, high-efficiency step-up LED drivers featuring precision current matching and robust fault protection - optimized for TV, monitor, and professional display markets.

FAQ

What is the minimum recommended current-sense resistor value for 300mA LED string operation?

The FB regulation voltage is 202mV ±7mV. For 300mA, R_SET = 202mV / 0.3A = 0.673Ω. Minimum practical value is 0.68Ω (standard E24), yielding 297mA. Lower values increase power dissipation and reduce accuracy due to tolerance stacking; 1% metal-film or thick-film resistors are recommended.

Can MP3393EY-LF operate without an external MOSFET?

No. The MP3393EY-LF is a step-up controller only - it lacks integrated power switches. The GATE pin drives an external NMOS, and CTLx pins drive external PNP transistors. Operation requires both external MOSFET and PNP devices per string; omitting either causes failure to regulate or immediate fault triggering.

How does the daisy-chain mode affect thermal performance compared to single-IC operation?

In daisy-chain mode, only the master IC drives the boost converter; the slave IC draws power from master's VCC and shares COMP loop. This reduces total power dissipation by ~45% versus two independent controllers, lowering junction temperature and improving reliability in thermally constrained enclosures.

What is the maximum allowable duty cycle and how does it relate to input/output voltage ratio?

The maximum duty cycle is 90%. For a given input (VIN) and output (VOUT) voltage, D ≈ (VOUT − VIN)/VOUT. At VIN = 9V and VOUT = 60V, D ≈ 85%, staying within limit. Exceeding 90% triggers current-limit protection via ISENSE pin, halting switching until reset - design must ensure worst-case D < 90% across operating range.

Is the FF pin active-high or active-low during fault conditions?

The FF pin is open-drain and active-low during faults. In normal operation, it is pulled high externally (typically to VCC or 3.3V). During thermal shutdown, LED open/short, or OVP, the internal NMOS turns on and pulls FF to GND - enabling direct connection to microcontroller GPIO with internal pull-up.

Does MP3393EY-LF support analog dimming and PWM dimming simultaneously?

No. Analog dimming (0.4–1.5V DC on DIM pin) and external PWM dimming are mutually exclusive modes. The IC detects DIM pin voltage level at startup: ≤0.4V enables PWM mode; ≥0.4V enables analog mode. Mixing signals causes undefined current regulation and potential instability.

What is the purpose of the ISENSE pin and can it be left unconnected?

The ISENSE pin senses inductor current for peak-current-mode control and cycle-by-cycle limiting. If not daisy-chained, it must be tied to GND - leaving it floating violates Absolute Maximum Ratings and may cause erratic switching or damage. In daisy-chain mode, it connects to the master IC's ISENSE node.