Monolithic Power Systems Inc. EV3924-U-00A

Overview

EV3924-U-00A from Monolithic Power Systems is an evaluation board designed to demonstrate the MP3924 quad-port IEEE 802.3af/at Power Sourcing Equipment (PSE) controller IC. It supports full PoE detection, 1-event/2-event classification, current limiting, and DC load disconnect detection across four independent ports, with I²C programmability and 9-bit ADC-based voltage/current monitoring. The board enables validation of Class 0–4 Powered Device (PD) handshaking under 44–57 V input.

For engineers reviewing the EV3924-U-00A datasheet, EV3924-U-00A pinout, EV3924-U-00A application, or EV3924-U-00A equivalent, this board provides hardware-level verification of MP3924's automatic mode operation, isolated I²C interface timing, thermal protection response, and per-port power shutdown behavior under overcurrent and over-power conditions.

Technical Context

The EV3924-U-00A implements the MP3924's complete PSE control stack on a single PCB, including four FDMC3612 N-channel MOSFETs for port switching, BSS123 gate drivers, SMBJ58A TVS diodes for surge protection, and precision 0.25 Ω current-sense resistors per channel. It interfaces via 3-wire I²C (SDAI, SDAO, SCL) with interrupt prioritization using two dedicated INT pins.

Board-level functionality mirrors MP3924's dual-mode operation: fully autonomous IEEE 802.3af/at compliance in automatic mode, or granular software control via I²C register access-including programmable current limits (e.g., 49.9 W max), VCC self-generation, and instantaneous ADC readouts of port voltage and current.

Key Specifications

Availability

EV3924-U-00A is available at Aetrix Electronics and suitable for PoE switch development, midspan injector qualification, and surveillance NVR/DVR system integration requiring stable component supply and repeatable IEEE 802.3af/at interoperability testing.

Supply support for EV3924-U-00A 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 emphasis on efficiency, integration, and reliability in power management solutions.

The MP3924 product line targets enterprise and industrial PoE infrastructure, delivering quad-port PSE control with integrated diagnostics and robust fault handling for next-generation networked power systems.

FAQ

What PoE standards does the EV3924-U-00A support?

The board demonstrates full IEEE 802.3af (Type 1) and 802.3at (Type 2) compliance through the MP3924 IC, including 1-event and 2-event classification, signature detection, and power negotiation up to Class 4 (30 W per port). It does not support 802.3bt (Type 3/4).

Does the EV3924-U-00A require external firmware or drivers?

No. The board operates autonomously in automatic mode without host intervention. For software control, MPS provides the MP3924 GUI software and EVKT-USBI2C-02 interface-no custom drivers are needed; it uses standard USB CDC/ACM enumeration on Windows/macOS/Linux.

Can the EV3924-U-00A power multiple PDs simultaneously?

Yes. All four ports operate independently and concurrently. Test results confirm simultaneous Class 4 PD connection with coordinated current limiting and priority-based shutdown when total input power exceeds 49.9 W.

What is the role of the two INT pins on the board?

INT1 and INT2 provide configurable interrupt priority signaling to the host controller. They indicate port-specific events (e.g., PD connect/disconnect, overcurrent, thermal warning) and support daisy-chained or multiplexed interrupt handling in multi-board systems.

Is isolated I²C communication implemented on the board?

Yes. The board uses separate SDAI (I²C input) and SDAO (I²C output) lines with optocoupler-ready routing, enabling galvanic isolation between host and PSE controller-critical for noise immunity in high-voltage PoE environments.

How is thermal protection verified on this evaluation board?

Thermal shutdown is triggered when the MP3924GU die temperature exceeds 150°C, causing immediate port disablement. Board layout includes thermal vias under the QFN-32 package and copper pour areas to replicate real-world heatsinking behavior during sustained 30 W/port operation.