Texas Instruments LM5071EVAL/NOPB

Overview

LM5071EVAL/NOPB from Texas Instruments is a Power over Ethernet (PoE) Powered Device (PD) evaluation board supporting IEEE 802.3af compliance, integrated auxiliary power interface, and current-mode PWM control for flyback/forward DC-DC converters. It features an internal 80V/400mA MOSFET, programmable classification (Class 0–4), UVLO with hysteresis, and soft-start. Designed for validating PoE-powered IP phones, wireless access points, and network cameras.

For engineers reviewing the LM5071EVAL/NOPB datasheet, LM5071EVAL/NOPB pinout, LM5071EVAL/NOPB application, or LM5071EVAL/NOPB equivalent, this evaluation platform enables rapid validation of PoE PD interface timing, auxiliary power handover, inrush current limiting, thermal shutdown behavior, and SMPS loop stability under real-world 48V PoE and 12V AC adapter inputs.

Technical Context

The LM5071EVAL/NOPB implements full IEEE 802.3af detection (1.8–10V), classification (12.5–25V), and powered operation (>25V) using dedicated RSIG/RCLASS pins and internal signature resistor disconnect logic. Its dual-input architecture supports seamless switchover between PoE (+48V) and auxiliary AC adapter (12V) via the AUX pin's 2.5V threshold with 0.5V hysteresis.

Onboard circuitry replicates the LM5071's internal 80V startup regulator, current-mode PWM controller (200 kHz typical, adjustable via RT), 0.5V cycle-by-cycle current limit, 1.25V FB reference, and thermal shutdown at 165°C. The board exposes all critical signals-including CS, COMP, FB, SS, and RT-for oscilloscope probing and loop compensation tuning.

Key Specifications

Availability

LM5071EVAL/NOPB is available at Aetrix Electronics and suitable for PoE-powered IP telephony, enterprise Wi-Fi access points, industrial IoT gateways, and networked surveillance systems requiring stable component supply and validated reference design integration.

Supply support for LM5071EVAL/NOPB 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

Texas Instruments is a global semiconductor company headquartered in Dallas, Texas, delivering analog and embedded processing solutions across industrial, automotive, and communications markets.

The LM5071 product line delivers integrated PoE PD controllers with auxiliary power interface, targeting cost-sensitive, space-constrained networked devices needing dual-input resilience and IEEE-compliant power negotiation.

FAQ

What is the primary function of the LM5071EVAL/NOPB evaluation board?

The LM5071EVAL/NOPB is a fully assembled and tested evaluation platform for the LM5071 PoE PD controller IC. It demonstrates IEEE 802.3af-compliant detection, classification, and power delivery while enabling validation of auxiliary power handover, current-mode DC-DC converter stability, and thermal protection behavior. Engineers use LM5071EVAL/NOPB to verify system-level timing, measure inrush profiles, tune compensation networks, and confirm interoperability with standard PSEs before final PCB layout.

Does LM5071EVAL/NOPB support both PoE and auxiliary AC adapter inputs simultaneously?

Yes - LM5071EVAL/NOPB implements true dual-input operation: PoE power is applied across the RJ45 jack (±48V), while auxiliary 12V DC is routed to the AUX input. The board's LM5071 IC automatically prioritizes auxiliary power when present (via AUX pin >2.5V), disabling PoE interface functions and enabling the PWM controller directly. When auxiliary power is removed, the LM5071EVAL/NOPB re-engages PoE detection and classification sequences without manual reset.

How is the classification current configured on LM5071EVAL/NOPB?

LM5071EVAL/NOPB provides jumpers and test points to configure RCLASS externally per IEEE 802.3af Class 0–4 requirements. For example, a 54.9Ω resistor between RCLASS and VEE sets Class 3 (26–30 mA). The board includes pre-populated resistors for Class 0 (open) and Class 2 (82.5Ω), with solder pads for user-defined values. Classification current is verified by measuring voltage drop across a precision sense resistor placed in series with the RCLASS path on the evaluation board.

Can LM5071EVAL/NOPB be used to evaluate non-isolated DC-DC topologies?

Yes - LM5071EVAL/NOPB supports both isolated (flyback) and non-isolated (buck-derived) converter implementations. Its FB pin connects directly to the output voltage divider, and the internal 1.25V reference enables direct feedback in non-isolated designs. The board includes test points for COMP, CS, and OUT to facilitate loop gain measurement, current-sense signal integrity analysis, and gate drive waveform capture - all essential for stabilizing non-isolated SMPS designs using LM5071EVAL/NOPB.

What thermal management features are implemented on LM5071EVAL/NOPB?

LM5071EVAL/NOPB incorporates thermal monitoring via the LM5071's built-in 165°C shutdown with 25°C hysteresis. The board uses 2-oz copper on power layers, thermal vias under the LM5071 TSSOP-16 package, and exposed pad grounding to dissipate heat during sustained 390mA current-limit events. Temperature profiling is supported through a dedicated thermistor test point near the IC, allowing correlation of junction temperature rise with load conditions and ambient airflow - critical for validating thermal margin in final enclosure designs using LM5071EVAL/NOPB data.