Monolithic Power Systems Inc. MP3309CGQG-P

Overview

MP3309CGQG-P from Monolithic Power Systems is a white LED step-up converter IC with I²C interface, designed for backlighting in compact portable displays. It operates from 2.7V–5.5V input, delivers up to 38V output, supports programmable switching frequency (300–1200 kHz), regulates LED current via 200mV ±1% feedback voltage, and integrates synchronous rectification with selectable non-synchronous mode for efficiency optimization in smartphones and tablets.

For engineers reviewing the MP3309CGQG-P datasheet, MP3309CGQG-P pinout, MP3309CGQG-P application, or MP3309CGQG-P equivalent, key selection criteria include its I²C-programmable OVP thresholds (13.5V/24V/35.5V), dual dimming support (analog via register + PWM on EN/PWML), thermal shutdown at 150°C, cycle-by-cycle current limit of 1.5A, and QFN-10 (1.4×1.8mm) package for space-constrained PCB layouts.

Technical Context

The MP3309CGQG-P uses peak-current-mode control with internal ramp compensation to stabilize operation above 50% duty cycle. Its error amplifier compares FB voltage against a digitally adjustable 200mV reference (31-step I²C-controlled range: 0–200mV), enabling precise analog dimming without external DACs.

Switching frequency is resistor-programmed (FREQ pin) from 300kHz to 1.2MHz, directly impacting inductor size and EMI performance. The I²C interface (400kHz, address 0x17) configures protection thresholds (OVP0/OVP1), dimming mode (DIMS), synchronous mode (SYNC), and enables/disables the IC-enabling dynamic system-level fault response and adaptive power management.

Key Specifications

Pinout & Package

MP3309CGQG-P is housed in a thermally enhanced 10-pin QFN package (1.4mm × 1.8mm, 0.4mm pitch) with exposed thermal pad for efficient heat dissipation in high-density mobile PCBs.

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, the MP3309CGQG-P provides superior flexibility through its 300–1200kHz programmable fSW, three-point OVP selection, and full I²C register access-including fault status readback-making it optimal for adaptive, safety-critical, or space-constrained portable display systems.

Availability

MP3309CGQG-P is available at Aetrix Electronics and suitable for smartphone backlighting, tablet display modules, feature phone keypad illumination, and portable medical display backlighting requiring stable component supply across production lifecycles.

Supply support for MP3309CGQG-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 mixed-signal ICs for power management, motion control, and automotive applications.

The MP3309CGQG-P belongs to MPS's WLED boost driver product line, engineered specifically for energy-efficient, digitally configurable backlighting in space- and thermal-constrained portable electronics.

FAQ

What is the maximum LED string voltage supported by MP3309CGQG-P?

The MP3309CGQG-P supports up to 38V output, verified by absolute maximum rating (VOUT ≤ +40V) and typical application validation with 8-series white LEDs (~28V nominal). This enables driving longer LED strings than competitors limited to 28–30V, reducing the need for parallel strings and associated current-matching complexity.

How does the I²C interface configure LED current without an external DAC?

The MP3309CGQG-P uses a 5-bit internal reference register (D0–D4) to set the feedback reference voltage from 0mV to 200mV in 31 discrete steps. Since LED current is calculated as I_LED = V_REF/R_FB, writing to this register digitally adjusts current amplitude-eliminating external DACs while maintaining ±1% accuracy at room temperature.

Can MP3309CGQG-P operate in non-synchronous mode, and why would I choose it?

Yes-setting the SYNC bit to '0' disables the internal synchronous MOSFET, requiring an external Schottky diode between SW and VOUT. This mode is preferred when LED string voltage is high (large duty cycle) or switching frequency exceeds 800kHz, where synchronous gate driver losses dominate efficiency. It trades BOM simplicity for thermal and efficiency optimization in specific operating points.

What protection features are readable via I²C, and how are they used?

The MP3309CGQG-P exposes three read-only fault bits via I²C register 0x01: LEDO (open-string), OTP (over-temperature), and VOS (VOUT-to-GND short). Host MCUs can poll these bits to distinguish fault causes-e.g., triggering different recovery sequences (cool-down delay for OTP vs. LED replacement alert for LEDO)-enabling robust system-level diagnostics without additional sensors.

What is the minimum recommended input capacitance, and why is dielectric type important?

A minimum 2.2μF X5R or X7R ceramic capacitor is recommended at VIN. These dielectrics maintain stable capacitance under DC bias and temperature-critical because input capacitor impedance at the switching frequency must stay below source impedance to prevent noise coupling. Using Y5V or Z5U types risks >50% capacitance loss at rated voltage, degrading ripple suppression and EMI performance.

How does the soft-start sequence prevent inrush current during power-up?

The MP3309CGQG-P implements a 32-step reference voltage ramp (320μs per step, total 10.24ms) from 0 to 200mV, combined with a reduced 0.7A cycle-by-cycle current limit active for the first 5ms. This coordinated approach limits peak inductor current and output capacitor charging surge-preventing voltage droop on shared rails and avoiding false UVLO triggers in multi-rail systems.

Is the thermal pad on the QFN-10 package required to be soldered, and what is its electrical role?

Yes-the exposed thermal pad must be soldered to a dedicated PCB copper pour connected to GND. It serves both thermal and electrical functions: lowering θ_JA from 140°C/W to ~45°C/W in standard layouts, and providing the primary return path for internal power MOSFET currents. Omitting this connection risks thermal shutdown at <50% load and violates JEDEC MO-220 mechanical compliance.