Analog Devices Inc./Maxim Integrated MAX5953AUTM+

Overview

The MAX5953AUTM+ from Maxim Integrated is an IEEE 802.3af-compliant Powered Device (PD) interface IC with integrated two-switch voltage-clamped DC-DC PWM controller and dual high-voltage power MOSFETs (0.4Ω R_DS(ON)). It delivers up to 15W output power across 11V–76V input, supports programmable inrush current control and adjustable UVLO, and operates in forward/flyback configurations for IP phones, wireless access nodes, security cameras, and computer telephony systems.

For engineers reviewing the MAX5953AUTM+ datasheet, MAX5953AUTM+ pinout, MAX5953AUTM+ application, or MAX5953AUTM+ equivalent, this page provides verified technical context, confirmed pin functions, real-world design meanings of key specs, and validated alternative options for PoE PD system design and qualification.

Technical Context

The MAX5953AUTM+ integrates a complete IEEE 802.3af PD front-end-including detection signature (<10µA offset), classification (Class 0–4), and isolation switch-with a voltage-mode PWM controller driving two internal 0.4Ω MOSFETs in a clamped two-switch topology. It supports synchronous rectification via look-ahead PPWM signal and features feed-forward control for fast input transient rejection.

Its dual-domain architecture separates PD interface (VEE-referenced) and DC-DC controller (GND-referenced) sections, with dedicated bias regulation (REGOUT: 8.75–11.0V), programmable soft-start (CSS), and fault-integration protection (FLTINT). The device guarantees glitch-free mode transitions using long deglitch time (0.32ms) and wide UVLO hysteresis (7.1V for MAX5953A).

Key Specifications

Pinout & Package

Package: 48-pin TQFN (7mm × 7mm), thermally enhanced, lead-free, exposed paddle connected to VEE.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Powered Device interface and DC-DC controller applications.

Compared with MAX5969B and NCP1095, the MAX5953AUTM+ uniquely combines IEEE 802.3af PD interface, clamped two-switch DC-DC controller, and dual 0.4Ω power MOSFETs in one 7mm × 7mm package-delivering 15W with minimal external components and >90% efficiency using synchronous rectification.

Availability

MAX5953AUTM+ is available at Aetrix Electronics and suitable for IP phones, wireless access nodes, security cameras, and computer telephony applications requiring stable component supply, long-term lifecycle support, and guaranteed 802.3af compliance.

Supply support for MAX5953AUTM+ 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 high-performance analog and mixed-signal ICs for power management, interface, sensing, and RF applications in industrial, communications, and consumer markets.

The MAX5953AUTM+ belongs to Maxim's Power-over-Ethernet PD controller product line, engineered to simplify 802.3af-compliant powered device implementation with monolithic integration of detection, classification, isolation, and DC-DC conversion.

FAQ

What is the UVLO configuration difference between MAX5953AUTM+ and MAX5953BUTM+?

The MAX5953AUTM+ features an adjustable undervoltage lockout threshold (default 38.6V) set via external resistor divider on the UVLO pin, enabling customization for nonstandard PSEs while maintaining IEEE 802.3af compliance. In contrast, MAX5953BUTM+ has a fixed lower UVLO threshold (35.4V) optimized for legacy pre-802.3af power-sourcing equipment. This makes MAX5953AUTM+ more flexible in modern deployments where PSE voltage tolerance varies.

Does MAX5953AUTM+ support synchronous rectification, and how is it implemented?

Yes, MAX5953AUTM+ supports synchronous rectification via its dedicated PPWM pin (pin 21), which outputs a look-ahead signal leading internal FET switching by ~100ns. This signal drives external gate drivers for secondary-side MOSFETs, reducing conduction losses and enabling >90% system efficiency. The timing is internally calibrated and does not require external compensation-simplifying design versus controllers requiring manual dead-time adjustment.

What is the maximum continuous power dissipation of MAX5953AUTM+ in its TQFN package?

The MAX5953AUTM+ in its 48-pin 7mm × 7mm thermally enhanced thin QFN package (T4877-6) delivers 2.22W continuous power dissipation at +70°C ambient, with a thermal resistance θ_JA of 36°C/W. Derating is 27.8mW/°C above +70°C, supporting reliable operation in compact enclosures typical of IP cameras and access points without forced airflow.

How does MAX5953AUTM+ handle inrush current limiting during power-up?

MAX5953AUTM+ implements programmable inrush current limiting via its GATE pin (pin 9): connecting a ceramic capacitor from GATE to OUT sets the slew rate of the internal isolation MOSFET's gate voltage, thereby controlling input current rise time. This prevents tripping of upstream PSE current limits and avoids voltage droop on shared PoE cables-critical for multi-port switches powering multiple devices simultaneously.

Can MAX5953AUTM+ operate in both forward and flyback DC-DC topologies?

Yes, MAX5953AUTM+ supports both forward and flyback configurations using its clamped two-switch topology. The internal high- and low-side MOSFETs (0.4Ω R_DS(ON)) and dedicated XFRMRH/XFRMRL pins allow direct connection to either topology's transformer windings. When configured as a buck converter using the high-side FET, it enables non-isolated 12V-to-5V conversion-extending flexibility beyond traditional isolated PoE applications.