TPS2371PW

Specialized Overview

The TPS2371PW is a legacy IEEE 802.3af compatible power interface switch for Powered Devices (PDs), manufactured by Texas Instruments in an 8-pin Plastic TSSOP package. It operates within an input voltage range of 44 V to 57 V and supports an operating junction temperature from 0°C to 70°C. The device incorporates a precision UVLO with a 20-ms off-time delay, programmable inrush current limiting ranging from 50 mA to 449 mA via an external resistor, and an internal 0.3-Ω low-side FET. It provides detection and classification signatures (Class 0–4) and interfaces directly with DC/DC converter soft-start circuits.

Specialized Feature Summary

• Performs complete detection, classification, and inrush current limiting protocols required for Legacy/IEEE 802.3af PoE compatibility.
• Integrates a low-side pass FET that activates at 36 V and disconnects below 30 V, managing the return path to the load.
• Features a dedicated output pin that acts as a current sink to control the soft-start timing of downstream DC/DC converters.

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 latest documentation to confirm the package type and tape-and-reel availability. Confirm the thermal performance requirements match the specified junction-to-ambient impedance for the TSSOP-8 configuration under your intended ambient conditions.

Specialized Selection Notes

Select this component when designing a Powered Device requiring strict compliance with the legacy IEEE 802.3af standard. Ensure the application utilizes an external resistor on the ILIM pin if the load capacitance exceeds 180 µF to maintain inrush current limits below 400 mA during startup.

Specialized Part Context

This part belongs to the TPS237x family of PoE interface switches. While functionally similar to newer standards like 802.3at, the TPS2371 is specifically engineered for legacy 15.4 W power budgets. It serves as the primary front-end controller between the Ethernet media and the internal power conversion stages.

Specialized Replacement Considerations

The TPS2371D is the equivalent device housed in an 8-pin SOIC package. For reel packaging variants, check for suffixes such as 'R' (e.g., TPS2371PWR). Verify pinout compatibility before substitution.

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 current limit between 50 mA and 449 mA.

What is the function of the EN_DC pin?

The EN_DC pin sinks 80 µA during startup to hold off the soft-start capacitor of a connected DC/DC converter. It becomes high-impedance once the load voltage reaches within 1.5 V of its final value, allowing the converter to start.

How does the device handle thermal protection?

If the junction temperature reaches the thermal shutdown threshold, the internal FET disconnects the load. The device will retry automatically after cooling; if the fault persists, it latches off after seven cycles until power is cycled.