Monolithic Power Systems Inc. MP3430GQ-Z

Overview

MP3430GQ-Z from Monolithic Power Systems is a monolithic 90V step-up converter with integrated high-side avalanche photodiode (APD) current monitoring, designed for optical receiver biasing. It delivers up to 90V output from 2.7–5.5V input, features 1.3MHz fixed-frequency current-mode control, and provides two precision APD monitor outputs with 1:10 and 1:2 current-mirror ratios for real-time optical power management in fiber-optic modules.

For engineers reviewing the MP3430GQ-Z datasheet, MP3430GQ-Z pinout, MP3430GQ-Z application, or MP3430GQ-Z equivalent, this device is selected for high-voltage, low-noise APD biasing where fast transient response, ±5% APD current monitoring tolerance, programmable over-current protection, and thermal shutdown are critical design requirements.

Technical Context

The MP3430GQ-Z implements a constant-frequency, current-mode boost architecture with internal compensation and soft-start, enabling stable regulation under wide input/output voltage ratios (e.g., 3.3V → 50V). Its PWM comparator compares a ramp-modulated current-sense signal against a 0.8V reference derived from the FB pin, delivering cycle-by-cycle current limiting and fast load transient recovery.

It integrates a dedicated high-side APD current mirror with dual buffered outputs (MON1, MON2), each clamped to ≤3.5V and capable of sourcing 0.1mA/mA (1:10) and 0.5mA/mA (1:2) mirrored current. The RLIM pin enables resistor-programmable APD over-current threshold from 0.36mA to 4.3mA, with 50ns response time to APD current transients.

Key Specifications

Pinout & Package

MP3430GQ-Z is housed in a thermally enhanced 3mm × 3mm QFN-16 package with exposed thermal pad (EP), optimized for high-voltage isolation and efficient heat dissipation in space-constrained optical modules.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar APD biasing and monitoring applications.

Compared with MAX3864E and TSM108, MP3430GQ-Z uniquely integrates high-voltage boost, dual-ratio APD monitoring, and programmable current limiting in a single 3mm×3mm QFN, reducing system footprint by >40% and enabling real-time optical safety compliance in next-gen fiber and LiDAR systems.

Availability

MP3430GQ-Z is available at Aetrix Electronics and suitable for fiber-optic transceivers, PON optical line terminals, LiDAR receiver modules, and medical pulse oximetry sensors requiring stable component supply and guaranteed long-term availability.

Supply support for MP3430GQ-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 over two decades of leadership in DC/DC conversion, motor drivers, and optical power management solutions.

The MP3430 product line targets high-voltage optical front-ends, specifically engineered to replace discrete APD bias supplies and external current monitors in fiber, LiDAR, and biomedical sensing applications.

FAQ

What is the maximum safe APD voltage that MP3430GQ-Z can deliver?

The MP3430GQ-Z is rated for up to 90V output and supports APD cathode connections up to 90V. Absolute maximum ratings specify MONIN, SW, and APD pins tolerate 100V transient stress, but continuous operation above 90V violates specification limits and risks instability or reliability degradation.

How does the RLIM pin set the APD over-current threshold?

The RLIM pin accepts a resistor to ground that sets the APD current limit per the equation I_APD = −122 × V_RLIM + 48 (mA), where V_RLIM is the voltage at RLIM. With typical RLIM values (13.7kΩ–137kΩ), the threshold ranges from 0.36mA to 4.3mA, enabling precise optical surge protection calibration.

Can MON1 and MON2 be used simultaneously without interference?

Yes - MON1 and MON2 are independently buffered current-source outputs with separate gain paths (1:10 and 1:2). They share AGND but drive separate external resistors (RMON1, RMON2); proper star grounding at AGND prevents crosstalk, and both outputs respond within 50ns/7μs respectively.

Why does MP3430GQ-Z require operation in discontinuous conduction mode (DCM)?

Due to its high voltage conversion ratio (e.g., 3.3V → 90V), the boost converter develops a right-half-plane zero that causes instability in continuous conduction mode (CCM). DCM eliminates this zero, ensuring phase margin >45° across all operating conditions - enforced by inductor selection per K-factor analysis in the datasheet.

Is the exposed thermal pad (EP) electrically connected internally?

Yes - the exposed pad is internally connected to PGND (pins 1 and 16). It must be soldered to a solid PCB ground plane with ≥4 thermal vias (0.3mm diameter) to achieve θ_JA = 60°C/W and sustain full 2.1W power dissipation at +25°C ambient.

Does MP3430GQ-Z support synchronization to an external clock?

No - the MP3430GQ-Z uses an internal 1.3MHz oscillator with no external sync capability. For systems requiring clock alignment (e.g., multi-channel LiDAR), interleaved operation must be achieved via EN pin sequencing or external timing controllers.

What is the minimum recommended output capacitor value and voltage rating?

A 0.1µF ceramic capacitor rated ≥100V is recommended. This value ensures ≤0.1% output ripple at full load and withstands worst-case voltage stress (e.g., 90V output + 10% margin). Lower capacitance increases ripple; lower voltage rating risks dielectric breakdown during transients.