Monolithic Power Systems Inc. MP3310EQ-LF-Z

Overview

MP3310EQ-LF-Z from Monolithic Power Systems is a monolithic step-up white LED driver IC with true PWM dimming, 47V output capability, 1.3A internal switch current limit, and adjustable 300kHz–1.2MHz switching frequency. It regulates LED current via external ISET resistor (e.g., 76.8mA at RISET = 60.4kΩ), supports up to 12-series/4-parallel WLED arrays, and integrates OVP, UVLO, thermal shutdown, and 0.3Ω internal MOSFET for LCD backlighting in portable displays.

For engineers reviewing the MP3310EQ-LF-Z datasheet, MP3310EQ-LF-Z pinout, MP3310EQ-LF-Z application, or MP3310EQ-LF-Z equivalent, this page delivers verified technical context on current-mode boost architecture, 500mV LED current sense reference, 10-pin QFN-3×3mm package layout, and design-critical parameters including VSW max = +47V, fSW programmability, and true PWM dimming control via EN/DIM pin.

Technical Context

The MP3310EQ-LF-Z implements fixed-frequency peak-current-mode control with internal 5V LDO (VCC) powering gate drivers and logic. Its error amplifier compares LED current-sense voltage against a precise 500mV reference, generating COMP voltage that modulates switch duty cycle to maintain regulation.

OVP threshold is set by external resistor divider on OVP pin (trip point = 1.24V), latching shutdown until enable reset; EN/DIM pin accepts 200Hz–2kHz square wave for true PWM dimming without color shift; FSET pin sets switching frequency via resistor (20kΩ–100kΩ yields 300kHz–1.2MHz), while ISET pin programs total LED current using ILED = 4605V / RISET.

Key Specifications

Pinout & Package

MP3310EQ-LF-Z uses a thermally enhanced 10-pin QFN package (3mm × 3mm, 0.5mm pitch) with exposed thermal pad connected to GND for optimal power dissipation (θ_JA = 50°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-up white LED driver applications.

Compared with RT9397BZSP and LM3409QMYX/NOPB, MP3310EQ-LF-Z uniquely combines programmable frequency, true PWM dimming, integrated 5V LDO, and 47V/1.3A capability in a 3×3mm QFN-making it optimal for space-constrained, multi-string LCD backlight designs requiring robust fault protection and ambient-adaptive brightness control.

Availability

MP3310EQ-LF-Z is available at Aetrix Electronics and suitable for LCD panel backlighting, digital picture frame illumination, and handheld computer display applications requiring stable component supply, RoHS-compliant packaging, and long-term production continuity.

Supply support for MP3310EQ-LF-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 core expertise in DC-DC conversion, LED drivers, and motor control solutions.

The MP3310 belongs to MPS's white LED backlight driver product line, engineered specifically for energy-efficient, compact, and reliable boost-based constant-current sources in portable and embedded display systems.

FAQ

What is the minimum input voltage required for MP3310EQ-LF-Z to start switching?

The MP3310EQ-LF-Z begins operation when VIN exceeds the under-voltage lockout (UVLO) rising threshold of 3.6V to 4.2V (typ. 3.9V). Below this, the IC remains in shutdown with quiescent current <1µA. Startup occurs only after VCC reaches UVLO threshold and COMP voltage rises to ~750mV.

Can MP3310EQ-LF-Z drive more than 12 series white LEDs?

No-its absolute maximum output voltage is +47V, and typical forward voltage for white LEDs is 2.8–3.6V. At 3.3V per LED, 12-series yields 39.6V, leaving 7.4V margin for diode drop, ripple, and tolerance. Driving 13-series (≥42.9V) risks exceeding VSW rating under transient conditions and violates safe operating area limits.

How does the true PWM dimming function differ from analog dimming on this IC?

True PWM dimming on MP3310EQ-LF-Z fully turns off the LED current path via the internal open-drain LED pin during low phase of EN/DIM signal-preserving LED forward voltage and chromaticity. Analog dimming (not supported) would vary ISET reference, causing color shift and reduced efficiency at low brightness.

Is the exposed thermal pad electrically isolated or must it connect to GND?

The exposed pad is internally connected to GND and must be soldered to a PCB GND plane. It serves both thermal dissipation (reducing θ_JA by ~30%) and electrical grounding-floating or connecting to other nets causes functional failure and thermal runaway.

What happens during an open LED string condition?

When an LED string opens, the feedback voltage at the LED pin drops to zero, causing the boost converter to increase output voltage until the OVP comparator senses ≥1.24V at the OVP pin. The IC then latches off the SW pin and holds shutdown until EN/DIM is cycled low-high.

Does MP3310EQ-LF-Z require external compensation components on the COMP pin?

Yes-COMP is the error amplifier output and requires an external RC network (e.g., 100pF capacitor + 10kΩ resistor to GND) to stabilize the current-mode control loop. Omitting compensation causes oscillation, poor transient response, or failure to regulate LED current accurately.

Can VCC be left unconnected if VIN exceeds 5.5V?

No-VCC must always be bypassed with a ceramic capacitor (e.g., 1µF X7R) to GND, even when VIN > 5.5V. The internal LDO supplies gate drive and logic; missing bypass causes erratic switching, increased noise, and potential thermal shutdown due to unstable VCC rail.