Analog Devices Inc./Maxim Integrated MAX5984AETI+

Overview

MAX5984AETI+ from Maxim Integrated is a single-port IEEE 802.3af/at Power Sourcing Equipment (PSE) controller with integrated 0.5Ω MOSFET and sense resistor, delivering up to 40W per port. It performs automatic PD discovery, classification (including Class 5 and 2-event), DC/AC load-disconnect detection, and features input UVLO/OVLO, thermal shutdown, and LED status indication - deployed in PoE midspan injectors and endpoint switches.

For engineers reviewing the MAX5984AETI+ datasheet, MAX5984AETI+ pinout, MAX5984AETI+ application, or MAX5984AETI+ equivalent, this page delivers verified technical context, exact pin functions, real-world PoE system integration constraints, and validated alternative PSE controllers for Class 5-compliant 40W power delivery.

Technical Context

The MAX5984AETI+ implements fully autonomous PSE control logic without firmware: its central state machine executes IEEE-mandated two-phase detection (3.8–4.2V / 9–9.6V probe), classification (16–20V probe), and 2-event mark-event sequencing. It integrates analog sensing (DET current, OUT voltage, OSC triangle wave), digital configuration (ILIM1/ILIM2 for Class 5 thresholds), and protection circuitry (foldback current limit, thermal shutdown at +150°C, DC/AC disconnect timers).

Its architecture combines a high-side analog supply (AGND referenced) with low-side digital logic (VEE_DIG/VEE), enabling direct connection to PoE transformer secondary windings. The integrated MOSFET (R_DS(ON) = 0.5Ω typ @ +25°C) and internal sense resistor eliminate external power components, while the 28-pin TQFN-EP package supports thermal dissipation up to 2758.6mW at +70°C ambient.

Key Specifications

Pinout & Package

MAX5984AETI+ uses a 28-pin Thin Quad Flat No-lead Exposed Pad (TQFN-EP) package measuring 5mm × 5mm, with the exposed pad thermally and electrically connected to AGND per layout guidelines.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PSE controller applications.

Compared with MAX5982AETI+, the MAX5984AETI+ delivers 33% more power (40W vs. 30W) and eliminates 3 external components; versus NCP1095DR2G, it reduces PCB area by 45% and removes FET selection, layout, and thermal management complexity.

Availability

MAX5984AETI+ is available at Aetrix Electronics and suitable for single-port PoE midspan injectors, enterprise VoIP switches, industrial IoT gateways, and wireless LAN access point power systems requiring stable component supply and full IEEE 802.3af/at compliance.

Supply support for MAX5984AETI+ 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

Maxim Integrated (now part of Analog Devices) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, communications, and computing applications.

The MAX5984AETI+ belongs to Maxim's PoE PSE controller product line, designed specifically to simplify IEEE 802.3af/at-compliant single-port power delivery with integrated power stages and autonomous operation - targeting space- and cost-sensitive networking equipment.

FAQ

What is the maximum power delivery capability of the MAX5984AETI+?

The MAX5984AETI+ delivers up to 40W per port when Class 5 operation is enabled via ILIM1/ILIM2 configuration. This is achieved using its integrated 0.5Ω MOSFET and programmable current limit (up to 950mA). At nominal 54V input, the device sustains continuous 40W output while maintaining thermal stability within its –40°C to +85°C operating range. The MAX5984AETI+ meets IEEE 802.3at Amendment 1 requirements for high-power PDs.

How does the MAX5984AETI+ implement 2-event classification for Class 5 PDs?

The MAX5984AETI+ implements 2-event classification through dedicated hardware logic triggered when the 2-EVENT pin is pulled low at reset. During classification, it applies two sequential voltage probes to DET and measures current response to distinguish Class 5 signatures from legacy classes. This handshake is mandatory per IEEE 802.3at Annex 33D and is executed autonomously - no firmware or host processor involvement is required for the MAX5984AETI+ to complete the sequence.

Can the MAX5984AETI+ operate in both end-point and midspan PoE configurations?

Yes, the MAX5984AETI+ supports both configurations via the MIDSPAN pin. When MIDSPAN is left unconnected (internally pulled high), the device enters midspan mode with 2.2s detection retry timing and cadence-based collision avoidance. When MIDSPAN is forced low, it operates in end-point mode with immediate detection retries. The MAX5984AETI+ automatically adapts its timing, voltage probing, and disconnect behavior to match the selected topology without external reconfiguration.

What protection features are built into the MAX5984AETI+?

The MAX5984AETI+ integrates six key protections: input undervoltage lockout (28.5V), overvoltage lockout (62.5V), overtemperature shutdown (+150°C), short-circuit response (<10µs), current foldback (activates below 27V V_AGND–V_OUT), and dual-mode load disconnect (DC threshold: 7.5mA; AC threshold: 130µA). All are implemented in analog hardware with no software dependency, ensuring fail-safe operation during fault conditions.

Is an external MOSFET required when using the MAX5984AETI+?

No, the MAX5984AETI+ includes an integrated 0.5Ω power MOSFET rated for continuous 40W delivery. Its ON-resistance is specified at 0.5Ω (typ) @ +25°C and 0.6Ω (typ) @ +85°C, eliminating the need for external switching elements, gate drivers, or current-sense resistors. This integration reduces solution size, simplifies layout, and improves thermal performance compared to discrete PSE controller + FET implementations.