TPS2371PWR

Specialized Overview

The TPS2371PWR is a legacy IEEE 802.3af compatible power interface switch for Powered Devices (PDs) in the Power over Ethernet (PoE) ecosystem. It integrates detection, classification, and an internal 0.3-Ω low-side FET to manage power delivery from Power Sourcing Equipment (PSE). The device operates within a recommended input voltage range of 48 V to 57 V and supports Class 0 through Class 4 PD classifications. Key electrical parameters include a typical sleep current of 250 mA during startup, a thermal shutdown threshold at 144°C with 20°C hysteresis, and a programmable inrush current limit ranging from 50 mA to 449 mA via an external resistor. It features a 20-ms UVLO off-time delay and interfaces directly with DC/DC converter soft-start circuits.

Specialized Feature Summary

• Integrates precision undervoltage lockout thresholds and a 20-ms delay timer to ensure reliable Legacy IEEE 802.3af PoE compatibility.
• Provides full detection and classification signature generation for Classes 0 through 4 using a single external resistor.
• Features a programmable inrush current limit that allows the use of load capacitors exceeding standard 180 µF limits.
• Includes an EN_DC output pin that actively sinks current to hold off downstream DC/DC converter soft-start until stable voltage is reached.

Specialized Applications

• VoIP Phones
• Internet Appliances
• Wireless LAN Access Points
• Bluetooth Access Points

Specialized Procurement Notes

Verify the specific ordering suffix against the manufacturer's official documentation to confirm package type and reel configuration. The 'PW' suffix indicates an 8-pin Plastic TSSOP package, while 'D' denotes an 8-pin Plastic SOIC. Ensure the selected variant matches the required thermal impedance and board layout specifications for the target application environment.

Specialized Selection Notes

Select this component when designing a Powered Device requiring strict compliance with Legacy IEEE 802.3af standards. It is suitable for applications needing integrated hot-swap capabilities and simplified DC/DC controller interfacing. Consider the thermal dissipation ratings based on the chosen package and ambient temperature conditions to ensure operation remains within the specified junction temperature limits.

Specialized Part Context

The TPS2371 serves as a dedicated interface between the Ethernet cabling and the internal power conversion stage of a Powered Device. It handles the complex handshake protocols defined by the IEEE 802.3af standard, including probing for valid signatures and managing power ramp-up. This integration reduces the external component count compared to discrete solutions, streamlining the design of PoE-enabled network equipment.

Specialized Replacement Considerations

Public confirmed substitute part numbers: TPS2371DR, TPS2371DG4, TPS2371PWRG4.

Specialized FAQ

How is the inrush current limit programmed?

The inrush current is set by connecting an external resistor (RLIM) between the ILIM pin (Pin 1) and the VEE pin (Pin 4). The value determines the limit between 50 mA and 449 mA.

What is the function of the EN_DC pin?

The EN_DC pin acts as a control output for the downstream DC/DC converter. It sinks 80 µA to keep the converter disabled during startup and releases it once the load voltage is within 1.5 V of the final value.

How does the device handle overload conditions?

In the event of a short circuit or overload, the device enters thermal shutdown, turning off the internal FET. It retries automatically; if the fault persists, it cycles seven times before latching off, requiring a power cycle to reset.