Monolithic Power Systems Inc. MP3430HQ-LF-P

Overview

MP3430HQ-LF-P from Monolithic Power Systems is a monolithic 90V step-up converter with integrated high-side avalanche photodiode (APD) current monitoring, featuring 1.3MHz fixed-frequency current-mode control, 1:10 and 1:2 APD current mirror outputs, and programmable APD over-current protection via RLIM pin. It delivers precise APD biasing in optical receivers requiring stable high-voltage generation and real-time photocurrent feedback.

For engineers reviewing the MP3430HQ-LF-P datasheet, MP3430HQ-LF-P pinout, MP3430HQ-LF-P application, or MP3430HQ-LF-P equivalent, this device is selected for fiber-optic transceiver designs where fast APD current monitoring (<50ns response), ±5% high-side monitor tolerance, and 90V output capability are critical to signal integrity and dynamic range.

Technical Context

The MP3430HQ-LF-P employs a constant-frequency, current-mode PWM architecture with internal ramp compensation and cycle-by-cycle current limiting, enabling fast transient response and stable regulation across wide input (2.7–5.5V) and output (up to 90V) ranges. Its integrated APD current mirror uses dedicated MON1 (1:10 ratio) and MON2 (1:2 ratio) outputs with <±5% gain tolerance and 2.2–3.5V clamped voltage compliance.

Control logic includes EN pin with 0.8–1.6V enable threshold and 150mV hysteresis, FB pin regulated at 0.77–0.824V reference, and RLIM-programmable APD current limit (0.36–4.3mA). Thermal shutdown activates at 160°C with 10°C hysteresis, and the 100V/0.9A internal NFET supports discontinuous conduction mode (DCM) operation essential for stability at high conversion ratios.

Key Specifications

Pinout & Package

MP3430HQ-LF-P is housed in a thermally enhanced 3mm × 3mm QFN-16 package with exposed thermal pad (EP), optimized for high-voltage isolation and low-inductance APD current sensing paths.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX3272EASA+ and LT3482EDD-1, MP3430HQ-LF-P uniquely integrates dual-ratio APD monitoring, programmable over-current protection, and 90V capability in a single 3×3mm QFN-reducing BOM count by ≥4 components and enabling tighter optical power control loops.

Availability

MP3430HQ-LF-P is available at Aetrix Electronics and suitable for fiber-optic transceivers, PON optical line terminals, and LiDAR receiver modules requiring stable component supply, RoHS-compliant packaging, and guaranteed long-term availability.

Supply support for MP3430HQ-LF-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 power ICs, with core expertise in DC-DC conversion, motor drivers, and optical power management.

The MP3430 product line targets high-voltage optical receiver subsystems, designed specifically to simplify APD biasing and photocurrent monitoring in fiber-optic, LiDAR, and medical sensing applications.

FAQ

What is the maximum APD cathode voltage supported by MP3430HQ-LF-P?

The MP3430HQ-LF-P supports up to 90V on the APD pin under normal operation, with absolute maximum rating of 100V. This enables direct biasing of high-gain APDs used in long-haul optical receivers and time-of-flight sensors without external voltage clamping.

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

The RLIM pin accepts an external resistor to ground, establishing a voltage that linearly programs the APD current limit between 0.36mA and 4.3mA. For example, a 27.2kΩ resistor sets a 2.5mA limit per the equation I_APD,MAX = 68 / R_RLIM (R_RLIM in kΩ, I in mA).

Can MON1 and MON2 be used simultaneously without interference?

Yes-MON1 and MON2 operate independently with separate current mirrors (1:10 and 1:2) and share only the APD current source. Their outputs are internally clamped to 2.2–3.5V and can drive separate external resistors (R_MON1, R_MON2) without crosstalk or loading effects.

What is the purpose of the MONIN pin, and how should it be decoupled?

MONIN supplies bias current to the internal APD monitor circuitry. It must be decoupled with a low-pass RC filter (e.g., 10Ω + 100nF) referenced to AGND to suppress switching noise from SW node coupling, ensuring <±5% monitor gain accuracy across temperature and load.

Does MP3430HQ-LF-P require external compensation components?

No-the MP3430HQ-LF-P features fully internal compensation, eliminating the need for external Type-II or Type-III compensation networks. This simplifies layout and improves reliability in space-constrained optical modules while maintaining phase margin >45° across operating conditions.

How does the device ensure stability at high conversion ratios (e.g., 3.3V to 90V)?

Stability is ensured by enforcing discontinuous conduction mode (DCM) operation via inductor selection criteria (K < K_CRIT). The IC's current-mode control and internal ramp compensation suppress right-half-plane zero effects inherent in high-ratio boost converters.

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

Yes-the exposed pad is internally connected to PGND and must be soldered to a large PCB copper plane. It serves both thermal dissipation (θ_JA = 60°C/W) and electrical grounding; floating or isolated connection degrades thermal performance and increases noise susceptibility.