Analog Devices Inc./Maxim Integrated MAX5922BEUI+

Overview

MAX5922BEUI+ 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. It performs PD detection (19kΩ–26.5kΩ signature), classification (Class 0–4), programmable current limit (via external R_SENSE), and provides POK/ZC/FAULT status outputs for PoE midspan or switch/router applications.

For engineers reviewing the MAX5922BEUI+ datasheet, MAX5922BEUI+ pinout, MAX5922BEUI+ application, or MAX5922BEUI+ equivalent, this page delivers verified technical context, exact pin functions, real-world timing values (e.g., 191–230ms total detection/classification delay), fault management modes (latch vs. autorestart), and validated alternatives for PoE PSE design validation and BOM optimization.

Technical Context

The MAX5922BEUI+ implements full IEEE 802.3af PSE functionality in three sequential phases: detection (VPBI = 4V, VPBII = 8V, t_DET = 88ms), classification (V_CLASS = 28V, t_CLASS = 15–26ms), and power delivery with slew-rate control (dV_OUT/dt ≤ 100 V/ms, dI_OUT/dt ≤ 35 A/ms). Its analog/digital ground separation (±4V offset) and 100µA PD leakage tolerance ensure robust operation in noisy LAN environments.

It features detection disable (DET_DIS pin), zero-current detection (V_ZCTH = 2.7–4.8mV, t_ZCDEL = 300–400ms), and overcurrent protection with foldback (V_FBSTOP = 18V, t_OC = 50–75ms). The UVLO threshold is fixed at 28V (rising), and fault response supports either latch-off (LATCH = high) or autorestart (LATCH = low, t_RESTART = 1.60–2.24s).

Key Specifications

Pinout & Package

MAX5922BEUI+ is housed in a 28-pin TSSOP package (JEDEC MO-153, 4.4mm × 9.7mm body, 0.65mm pitch), rated for -40°C to +85°C ambient operation. Thermal pad exposed on underside requires solder connection to PCB ground plane for thermal management.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX5922AEUI+ and MAX5922CEUI+, the MAX5922BEUI+ provides identical detection/classification timing and current-limit accuracy but excludes DCA functionality-making it optimal for endspan switches or midspan injectors where only DET_DIS-controlled startup is needed, reducing pin count and simplifying layout.

Availability

MAX5922BEUI+ is available at Aetrix Electronics and suitable for power-over-LAN infrastructure, enterprise VoIP deployments, and industrial IP camera networks requiring stable component supply, long-term lifecycle support, and guaranteed IEEE 802.3af compliance.

Supply support for MAX5922BEUI+ 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 demanding industrial, communications, and computing applications.

The MAX5922BEUI+ belongs to Maxim's PoE PSE controller product line, engineered specifically for IEEE 802.3af-compliant single-port power sourcing in endspan and midspan network equipment with integrated MOSFET and comprehensive fault management.

FAQ

What is the UVLO threshold for MAX5922BEUI+?

The MAX5922BEUI+ has a fixed undervoltage lockout (UVLO) threshold of 28V (rising), with 2.5V hysteresis. This means the device remains in shutdown until the IN supply rises above 28V, and does not exit shutdown until VIN exceeds that threshold. The MAX5922BEUI+ does not support external UVLO adjustment - unlike the MAX5922AEUI+, which uses the UVLO pin for programmability.

Does MAX5922BEUI+ support detection collision avoidance (DCA)?

No, the MAX5922BEUI+ does not implement detection collision avoidance circuitry. While the MAX5922AEUI+ uses the DCA pin to enable back-off timing (t_DCA = 2.8s), and the MAX5922CEUI+ has DCA permanently enabled, the MAX5922BEUI+ omits this function entirely. Its DCA pin is non-functional - confirmed by datasheet Figure 2 note and electrical characteristics table exclusions.

How is current limiting configured on MAX5922BEUI+?

Current limiting on the MAX5922BEUI+ is set by an external sense resistor (R_SENSE) connected between DRAIN and IN. With the standard 0.5Ω±1% resistor, the device limits output current to 406–442mA, based on its fixed 203–221mV current-sense threshold (V_ILIM). The MAX5922BEUI+ also provides foldback (V_{ILIM_fb} = 64–76mV) and overcurrent timeout (t_OC = 50–75ms) for robust short-circuit protection.

What is the role of the DET_DIS pin on MAX5922BEUI+?

The DET_DIS pin on MAX5922BEUI+ disables both PD detection and classification when driven high, causing the device to power on immediately after EN goes high - bypassing the full 191–230ms IEEE 802.3af sequence. When DET_DIS is low, detection and classification proceed normally. This pin is exclusive to MAX5922B/C variants and is not present in the MAX5922AEUI+.

What package type and temperature rating does MAX5922BEUI+ use?

The MAX5922BEUI+ is supplied in a 28-pin TSSOP package (4.4mm × 9.7mm, 0.65mm pitch) with exposed thermal pad, rated for operation from -40°C to +85°C ambient temperature. This package matches the MAX5922AEUI+ and MAX5922CEUI+, ensuring footprint compatibility across the MAX5922 family for design reuse and variant selection.