Analog Devices Inc./Maxim Integrated MAX5922BEUI+T

Overview

MAX5922BEUI+T from Maxim Integrated is a single-port IEEE 802.3af-compliant power-sourcing equipment (PSE) controller with integrated 0.45Ω N-channel MOSFET, operating from +32V to +60V input, featuring programmable UVLO (28V), 100µA PD leakage tolerance, and zero-current detection with ZC output. It enables PoE midspan or endpoint power injection in switches/routers and network adapters.

For engineers reviewing the MAX5922BEUI+T datasheet, MAX5922BEUI+T pinout, MAX5922BEUI+T application, or MAX5922BEUI+T equivalent, key selection criteria include IEEE 802.3af compliance, detection disable (DET_DIS) support, 28-pin TSSOP package, -40°C to +85°C operation, and midspan-compatible current-limit foldback with fault management.

Technical Context

The MAX5922BEUI+T implements full IEEE 802.3af PD detection (19kΩ–26.5kΩ resistive signature, ≤0.6µF capacitance), classification (Class 0–4), and power delivery with integrated 0.45Ω MOSFET. It supports both endpoint (signal-pair) and midspan (spare-pair) topologies, with DET_DIS input enabling immediate power-on bypassing detection/classification.

Its analog/digital ground separation (±4V offset), 1.8V–5V logic-compatible inputs, and dual fault signaling (FAULT for overcurrent/overtemperature, ZC for zero-current) enable robust system-level integration. Startup slew-rate control (100 V/ms, 35 A/ms) minimizes EMI during power-up.

Key Specifications

Pinout & Package

MAX5922BEUI+T is housed in a 28-pin TSSOP package (4.4mm × 9.7mm, 0.65mm pitch), with exposed pad for thermal dissipation. Analog and digital grounds are separated but require single-point connection per layout guidelines.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar power-sourcing equipment applications.

Compared with MAX5922AEUI+T and MAX5922CEUI+T, the MAX5922BEUI+T uniquely offers DET_DIS control without DCA circuitry - optimizing flexibility for endpoint PSEs or deterministic midspan systems where collision avoidance is managed externally or unnecessary.

Availability

MAX5922BEUI+T is available at Aetrix Electronics and suitable for switch/router inline power, midspan injectors, single-port PoE adapters, and computer telephony systems requiring stable component supply across industrial temperature ranges and long production lifecycles.

Supply support for MAX5922BEUI+T 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) designs precision analog, mixed-signal, and power management ICs for industrial, communications, and computing applications.

The MAX5922 product line delivers fully integrated IEEE 802.3af PSE controllers targeting cost-sensitive, space-constrained PoE infrastructure equipment - emphasizing single-chip simplicity, robust fault handling, and seamless interoperability.

FAQ

What is the UVLO threshold for MAX5922BEUI+T?

The MAX5922BEUI+T features a fixed undervoltage lockout threshold of 28V (typical), with hysteresis of 2.5V. This ensures the device remains in shutdown until the IN supply exceeds 28V, preventing unstable operation during brownout conditions. The threshold is internally set and not adjustable - unlike the MAX5922A variant which allows external resistor programming. This value is confirmed in the Electrical Characteristics table under "Default VIN UVLO" for MAX5922B/MAX5922C.

Does MAX5922BEUI+T support detection collision avoidance (DCA)?

No, the MAX5922BEUI+T does not support detection collision avoidance. Unlike the MAX5922A (which has a dedicated DCA pin) or MAX5922C (with DCA permanently enabled), the MAX5922B variant omits DCA functionality entirely. Instead, it provides DET_DIS (Pin 24) to bypass detection/classification - offering deterministic control for known-good PDs without relying on randomized back-off timing.

How is current limiting configured on MAX5922BEUI+T?

Current limiting on the MAX5922BEUI+T is configured using an external sense resistor (R_SENSE) connected between DRAIN and IN. With a typical sense voltage threshold of 212mV, a 0.5Ω ±1% resistor sets a nominal current limit of 424mA. The device monitors (VIN – VDRS) continuously and enters regulated current limit within 1µs of overload detection, supporting foldback and duty-cycle limiting for sustained fault conditions.

What are the key differences between MAX5922BEUI+T and MAX5922AEUI+T?

The MAX5922BEUI+T and MAX5922AEUI+T differ in UVLO threshold (28V vs. 38V), DCA support (none vs. pin-controlled), and DET_DIS availability (present vs. absent). The MAX5922BEUI+T adds DET_DIS for detection bypass - a feature absent in the MAX5922AEUI+T - while omitting DCA. Both share identical 28-pin TSSOP packaging, -40°C to +85°C rating, and core IEEE 802.3af compliance.

Can MAX5922BEUI+T be used in midspan PoE applications?

Yes, the MAX5922BEUI+T is explicitly designed for midspan PoE applications, delivering power over spare pairs (pins 4–5, 7–8). Its DET_DIS pin allows immediate power-on when PD identity is pre-verified - eliminating reliance on detection collision avoidance. The device meets all IEEE 802.3af requirements for midspan PSEs, including PD signature validation (19kΩ–26.5kΩ), classification (Class 0–4), and current-limit foldback during fault conditions.