Monolithic Power Systems Inc. EV3908DK-01A

Overview

EV3908DK-01A from Monolithic Power Systems is an evaluation board for the MP3908DK isolated flyback DC-DC controller IC, configured to deliver a regulated 5V/5A (25W) output from a 36–72V input. It implements synchronous rectification via external MOSFETs, supports adjustable output voltage via feedback resistors, and operates at a fixed 250kHz switching frequency.

For engineers reviewing the EV3908DK-01A datasheet, EV3908DK-01A pinout, EV3908DK-01A application, or EV3908DK-01A equivalent, this board enables rapid validation of high-efficiency isolated power designs targeting PoE, telecom brick modules, and CCFL backlight supplies - with verified startup behavior, cycle-by-cycle current limiting, and <10μA shutdown current.

Technical Context

The EV3908DK-01A implements a current-mode controlled flyback topology using the MP3908DK controller in a transformer-isolated configuration. It integrates primary-side sensing, synchronous gate drive outputs, and optocoupler-based secondary-side feedback via PC817B for precise 5V regulation under full 5A load.

Key control features include under-voltage lockout (UVLO), cycle-by-cycle current limiting, and a 180μA quiescent current in active operation. The board uses Würth transformers (7491194501 for power stage, 750340060 for driver) and Vishay Si7450/Si4840 MOSFETs to achieve high efficiency in a compact 7.2cm × 4.5cm × 1.4cm form factor.

Key Specifications

Availability

EV3908DK-01A is available at Aetrix Electronics and suitable for Power over Ethernet (PoE) injectors, telecom isolated DC-DC bricks, and TV CCFL backlight power supplies requiring stable component supply, quick-turn prototyping, and production-ready reference design validation.

Supply support for EV3908DK-01A 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 expertise in DC-DC conversion, LED drivers, and motor control solutions.

The MP3908DK product line targets isolated flyback and forward converter applications requiring high efficiency, tight output regulation, and robust protection - optimized for telecom, industrial, and display power systems.

FAQ

What input voltage range does the EV3908DK-01A support?

The EV3908DK-01A accepts 36V to 72V DC input, covering common telecom and industrial DC bus standards. Operation is verified across this full range with stable 5V/5A output and thermal performance within limits at 25°C ambient. Input undervoltage lockout activates below ~33V to prevent erratic startup.

How is output voltage adjusted on this evaluation board?

Output voltage is set by the R1–R2 feedback resistor divider connected to the MP3908DK's FB pin. Default values (R1 = 1kΩ, R2 = 20kΩ) yield 5V; changing R2 alters V_OUT per the formula V_OUT = 1.24V × (1 + R2/R1). The TLV431 shunt regulator provides precision reference for this loop.

Does the board support remote enable/disable functionality?

Yes - the EN pin (U1 Pin 5) accepts a logic-level signal: driving it below 2V enables regulation; pulling it above 2V disables the controller and reduces supply current to ≤10μA. This allows system-level power sequencing and standby control without external circuitry.

What isolation rating does the EV3908DK-01A provide?

The board achieves reinforced isolation via the Würth 7491194501 transformer (primary-to-secondary creepage ≥8mm, clearance ≥6mm) and optocoupler feedback (PC817B). It meets IEC 60950-1 basic insulation requirements for 3000V_RMS input-to-output withstand, validated per MPS test reports.

Can this board be used for forward converter topologies?

Yes - the MP3908DK controller supports both flyback and forward modes. The EV3908DK-01A is configured as flyback, but its schematic and layout accommodate forward topology rework: transformer T1 can be replaced with a forward-compatible unit, and synchronous rectifier timing may require minor gate drive adjustments per MPS AN-103 application note.

What are the thermal limitations during continuous 5A operation?

At 48V_IN/5V_OUT/5A, measured board temperature rise is ≤28°C above ambient (25°C) with natural convection. Hotspots occur at Q2 (Si7450) and T1; derating is recommended above 60°C ambient. No forced airflow or heatsinks are required for nominal operation per test report Rev. 1.0.