Monolithic Power Systems Inc. MEZS84801A

Overview

mEZS84801A from Monolithic Power Systems is a fully assembled, IEEE 802.3af-compliant PoE power supply module delivering 12V/1A (12W) from a 37–57V PSE input, featuring primary-side regulation, no optocoupler feedback, and integrated over-current/over-temperature/over-voltage protection. It targets midspan and endpoint PoE-powered devices requiring compact, certified DC-DC conversion.

For engineers reviewing the mEZS84801A datasheet, mEZS84801A pinout, mEZS84801A application, or mEZS84801A equivalent, key selection criteria include its 140kHz switching frequency, ±4% output voltage accuracy, 180mV ripple at 1A, 84.5% efficiency with input bridge included, and native support for 802.3af Class 3 power classification.

Technical Context

The mEZS84801A implements a primary-side regulated flyback topology using the MP8007 controller (QFN-28), eliminating optocoupler dependency via auxiliary winding sensing. It accepts standard PoE input (37–57V) and delivers tightly regulated 12V output with line regulation of ±0.5% and load regulation of ±0.2%.

Its protection architecture includes cycle-by-cycle current limiting, thermal shutdown at ~150°C, and output overvoltage clamping. Start-up time is 110ms from VIN application to regulated VOUT, and minimum load requirement is 10mA to maintain regulation.

Key Specifications

Availability

mEZS84801A is available at Aetrix Electronics and suitable for IEEE 802.3af-compliant IP telephony systems, low-power wireless access points, and networked security cameras requiring stable component supply and pre-certified PoE power conversion.

Supply support for mEZS84801A 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 power management ICs and modules for industrial, computing, and communications applications.

The mEZS84801A belongs to MPS's mEZ™ series of plug-and-play PoE power supply modules, designed to accelerate development of IEEE 802.3af/at-compliant powered devices by integrating magnetics, protection, and regulation into a single surface-mount assembly.

FAQ

Is mEZS84801A compatible with IEEE 802.3at (PoE+)?

No. The mEZS84801A is explicitly designed and certified for IEEE 802.3af (Class 3, up to 12.95W). Its input voltage range (37–57V), output power (12W), and internal MP8007 configuration do not support 802.3at's higher power classes or extended voltage range. For PoE+, consider MPS's mEZS84802A or similar 802.3at modules.

Does mEZS84801A require external feedback components?

No. It uses primary-side regulation with auxiliary winding sensing on T2, eliminating the need for optocouplers, TL431 shunt regulators, or secondary-side feedback resistors. All compensation and regulation are handled internally by the MP8007 controller.

What is the role of J1, J3, and J4 connectors?

J1 is an 18-pin RJ45-style jack accepting PoE input (pins 1–4 for PSE LAN pair, pins 13–16 for 12V/GND output); J3 and J4 are 4-pin header blocks providing direct access to VOUT, GND, VDD, and VSS for test or integration into custom enclosures.

Can mEZS84801A operate without forced airflow?

Yes. Designed for natural convection cooling, it sustains full 1A output at +85°C ambient when mounted on a standard FR4 PCB with recommended copper pour. Derating is not required below 85°C, and MTBF is calculated at 4185×10³ hours per MIL-HDBK-217F.

How is over-current protection implemented?

Over-current protection is achieved via cycle-by-cycle peak current limiting in the MP8007 controller, monitored through the R7 sense resistor (20Ω) in series with the primary switch. Fault triggers hiccup-mode restart after thermal recovery, preventing latch-up during sustained overload.

What safety certifications does mEZS84801A hold?

The module complies with IEEE 802.3af and meets reinforced insulation requirements per IEC 60950-1 and UL 60950-1. It incorporates creepage/clearance design per EN 62368-1, including 8mm spacing between primary and secondary sides and reinforced isolation on T1/T2 transformers.