Monolithic Power Systems Inc. MP3309GQG-Z

Overview

MP3309GQG-Z from Monolithic Power Systems is a synchronous boost white LED driver IC operating from 2.7V–5.5V input, delivering up to 35V output with ±1% 200mV feedback reference, programmable 300kHz–1.2MHz switching frequency, and dual analog/PWM dimming support. It regulates LED current via external low-side sense resistor in portable displays requiring compact, high-efficiency backlighting.

For engineers reviewing the MP3309GQG-Z datasheet, MP3309GQG-Z pinout, MP3309GQG-Z application, or MP3309GQG-Z equivalent, key selection criteria include its 200mV FB accuracy, QFN-10 (1.4mm×1.8mm) footprint, integrated thermal/UVLO/OVP protections, and dual-dimming interface compatibility with smartphone and tablet display designs.

Technical Context

The MP3309GQG-Z employs peak-current mode control with internal ramp compensation to ensure stable operation at duty cycles >50%, using a 200mV precision reference to regulate LED current through an external sense resistor. Its synchronous rectification architecture integrates both high-side and low-side MOSFETs, eliminating external diode losses.

Dimming is implemented via two independent paths: EN/PWML accepts 200Hz–2kHz PWM for coarse brightness control with shutdown capability on >20ms low pulse, while PWMH supports >20kHz analog dimming via internal RC filtering. Open-string protection triggers at 35.5V OVP with 2.5V hysteresis, and startup limits inrush current to 0.8A for 5ms.

Key Specifications

Pinout & Package

MP3309GQG-Z is housed in a thermally enhanced QFN-10 package (1.4mm × 1.8mm, 0.5mm pitch) with exposed thermal pad for efficient heat dissipation in thin-profile portable devices.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar white LED boost driver applications.

Compared with RT9397BZSP and TPS61165DRVR, MP3309GQG-Z uniquely balances analog+PWM dimming in a 1.4mm×1.8mm footprint with 200mV ±1% FB accuracy - ideal for space-constrained, high-uniformity portable displays where dual-dimming simplifies firmware and eliminates external DACs.

Availability

MP3309GQG-Z is available at Aetrix Electronics and suitable for smartphone backlighting, tablet display drivers, and portable media player designs requiring stable component supply, long-lifecycle availability, and RoHS-compliant packaging.

Supply support for MP3309GQG-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 power management ICs, with design centers in the US, China, and Taiwan, and global manufacturing partnerships.

The MP3309 belongs to MPS's WLED boost driver product line, engineered specifically for compact, high-efficiency backlighting in battery-powered consumer displays where thermal performance, dimming fidelity, and PCB area are critical constraints.

FAQ

What is the minimum recommended input capacitance for MP3309GQG-Z?

A 4.7μF X5R/X7R ceramic capacitor is recommended at VIN, placed as close as possible to pins 2 (VIN) and 6 (GND). This value ensures low impedance at 600kHz switching frequency, suppresses input surge current, and prevents coupling of switching noise into the power rail - critical for stable LED current regulation and EMI compliance.

How does the MP3309GQG-Z handle open LED string faults?

The IC monitors VOUT and enters OVP shutdown when voltage exceeds 35.5V (typical), with 2.5V hysteresis. During an open condition, the error amplifier drives COMP high, charging the output capacitor until OVP threshold is reached. Switching halts immediately, protecting downstream components - recovery occurs automatically once VOUT drops below 33V.

Can MP3309GQG-Z operate without the BST capacitor?

No. The BST pin requires a 10nF ceramic capacitor connected between BST and SW to bootstrap the gate drive voltage for the internal high-side MOSFET. Omitting this capacitor prevents proper high-side switch turn-on, causing failure to regulate output voltage and potential thermal overstress of the low-side switch.

What is the maximum LED string voltage supported by MP3309GQG-Z?

The absolute maximum VOUT rating is +40V, but the functional overvoltage protection threshold is 35.5V. For reliable operation, the LED string forward voltage must remain ≤33V to maintain 2.5V hysteresis margin below OVP - supporting up to 10 white LEDs (3.3V each) at room temperature with adequate headroom.

How does the internal soft-start function during enable?

Upon EN/PWML assertion, the MP3309GQG-Z limits peak inductor current to 0.8A for 5ms before ramping to full 1.5A current limit. This controlled startup prevents inrush current spikes that could destabilize the input supply or trigger upstream current-limiting circuits in battery-powered systems.

Is the FREQ pin internally pulled down or should it be externally terminated?

The FREQ pin has no internal pull-down and must be externally connected to GND via a resistor to set switching frequency. Leaving it floating causes undefined oscillator behavior and unstable regulation - the datasheet explicitly warns against floating this pin.

What thermal derating applies above 25°C ambient?

With θ_JA = 140°C/W, power dissipation must be reduced linearly above 25°C: P_D(MAX) = (150°C − T_A) / 140°C/W. At 70°C ambient, max continuous power drops to 0.57W - requiring careful layout and thermal pad soldering to sustain full-load operation in enclosed handheld enclosures.