Monolithic Power Systems Inc. EV9928-L-00C

Overview

EV9928-L-00C from Monolithic Power Systems is a QFN-20 (3mm×4mm) evaluation board for the MP9928 synchronous step-down controller, designed to demonstrate 6–60V input-to-5V/7A output conversion using dual N-channel MOSFETs, programmable 100–1000kHz switching frequency, and cycle-by-cycle current limiting in PoE power supply applications.

For engineers reviewing the EV9928-L-00C datasheet, EV9928-L-00C pinout, EV9928-L-00C application, or EV9928-L-00C equivalent, this board provides validated reference design, thermal performance data at 24V_IN/5V_OUT, full protection implementation (OVP/OCP/thermal shutdown), and layout guidance for high-voltage buck controller integration.

Technical Context

The EV9928-L-00C implements the MP9928's current-mode PWM control architecture with external frequency programming via resistor or synchronization input (SYNCO), supporting noise-sensitive industrial and PoE systems. It integrates precision over-voltage protection (OVP) with ±1% threshold accuracy and cycle-by-cycle current limit with selectable threshold via R7 (0.007Ω).

This four-layer board uses a 4.7μH power inductor (Wurth 7443551470), dual SQJ850EP MOSFETs (60V/24A/23mΩ), and optimized gate drive routing to sustain 7A continuous output at 5V with <15mV ripple under full load, verified at 24V_IN and 25°C ambient.

Key Specifications

Availability

EV9928-L-00C is available at Aetrix Electronics and suitable for PoE-powered devices, USB charging infrastructure, industrial control power supplies, and linear battery charger bias circuits requiring stable component supply and rapid prototyping validation.

Supply support for EV9928-L-00C 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 ISO 9001-certified quality systems and global distribution.

The MP9928 product line delivers high-voltage synchronous buck controllers for demanding input ranges (up to 60V), targeting PoE, industrial, and automotive auxiliary power applications where efficiency, reliability, and compact layout are critical.

FAQ

What input voltage range is supported, and what happens below 6V?

The EV9928-L-00C board is configured for 6–60V input per the MP9928's operational specification. While the MP9928 IC itself can start at 4V, output regulation fails below 6V due to insufficient duty cycle margin to maintain 5V; the board's feedback network and MOSFET gate drive are optimized for ≥6V operation.

How is output over-voltage protection implemented and tested?

OVP is implemented using the MP9928's internal comparator monitoring the FB pin, triggering immediate shutdown if V_OUT exceeds 5.5V (110% of 5V). Test reports confirm response within 200ns and latch-off behavior until VIN reset, validated across temperature and line/load transients per Rev. 1.01 test data.

Can the switching frequency be synchronized to an external clock, and what is the required signal format?

Yes - the SYNCO pin accepts TTL/CMOS-compatible square-wave inputs from 100kHz to 1MHz. The board includes series termination (R6, NS) and AC-coupling (C7, 680pF) to suppress jitter; synchronization locks phase and eliminates beat frequencies in multi-rail systems.

What is the role of the 0.007Ω resistor (R7) and how does it affect current limiting?

R7 sets the cycle-by-cycle current limit threshold: I_LIM = 50mV / 0.007Ω ≈ 7.14A. This matches the 7A rated output and ensures MOSFET SOA compliance during overload. The value is placed in the high-side source path of the bottom FET for accurate sensing.

Does the board include a power-good indicator, and how is it configured?

Yes - the PG pin drives a dedicated open-drain output that asserts high when V_OUT is within ±10% of 5V for >2ms after soft-start. On this board, PG connects directly to header JP1 (pin 3) with no pull-up; users must add a 10kΩ pull-up to V_OUT for active-high logic.

Is thermal performance characterized, and what heatsinking is recommended?

Thermal imaging at 24V_IN/7A shows U1 (MP9928GL) case temperature ≤68°C with 200LFM airflow. The QFN-20 package uses exposed pad soldered to internal ground plane; no external heatsink is needed, but board-level copper area ≥250mm² under U1 is required for spec-compliant operation.