TPS2370D

Specialized Overview

The TPS2370D is an integrated power interface switch for IEEE 802.3af Powered Devices (PDs). It provides PD detection and classification signatures, features a programmable inrush current limit, and includes an internal 0.3-Ω low-side FET. The device interfaces with DC/DC soft-start circuits and incorporates internal thermal protection to disconnect the load. Operating within a temperature range of 0°C to 70°C, it supports input voltages up to 57 V. Key electrical parameters include a sleep current of 180 µA to 300 mA during startup, a thermal shutdown threshold at 144°C, and a typical supply offset current of 3 µA.

Specialized Feature Summary

• Integrated compliance with IEEE 802.3af standards for powered devices
• Internal 0.3-ohm low-side pass FET for maximum power delivery
• Programmable inrush current limiting via external resistor
• Direct interface to DC/DC converter enable or soft-start pins

Specialized Applications

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

Specialized Procurement Notes

Verify the specific package variant required, as the 'D' suffix denotes an 8-pin SOIC package. Confirm that the standard commercial operating temperature range of 0°C to 70°C meets the environmental requirements of the target deployment. Ensure the design accommodates the necessary external components for detection resistance and inrush current programming as specified in the official datasheet.

Specialized Selection Notes

Select this component when designing a PoE-powered device requiring strict adherence to the IEEE 802.3af standard. It is suitable for applications needing minimal external part counts and integrated thermal protection. Consider the 0.3-ohm internal FET resistance when calculating total power dissipation and efficiency. Verify compatibility with the downstream DC/DC converter's soft-start timing requirements.

Specialized Part Context

The TPS2370 belongs to Texas Instruments' legacy portfolio of Power-over-Ethernet controllers designed specifically for the 802.3af standard. It serves as a front-end interface between the Ethernet cable and the local DC/DC conversion stage. This family focuses on simplifying PD implementation by integrating detection, classification, and switching logic into a single compact package.

Specialized Replacement Considerations

The TPS2376 series offers enhanced performance with lower on-resistance and support for higher power classes. Designers upgrading from the TPS2370 should evaluate pinout compatibility and verify that the new controller meets the specific power budget and thermal management requirements of the application.

Specialized FAQ

How is the inrush current limited?

The inrush current is programmed using an external resistor connected between the ILIM pin and the VEE pin. This allows designers to accommodate larger load capacitances while staying within IEEE 802.3af limits.

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 hold the converter off during startup and releases it once the load voltage is within 1.5 V of the final value, enabling a controlled soft-start.

How does the device handle thermal overload?

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