CCS/TPS23880: TPS23880 legacy-AT PD device support?

Hi Ken!

The TPS23880 can support pre-BT PD devices! You do not need to configure any special registers in order to recognize older devices. The IEEE802.3bt standard is backwards compatible, and interoperable with, IEEE802.3af and IEEE802.3at PD controllers.

More information about the .bt standard can be found here --> training.ti.com/power-over-ethernet-getting-started-new-standard

This portal has a lot of useful PoE information and a great white paper co-written by our Design Manager, and IEEE802bt standard comment editor, David Abramson.

Here is a direct link to that white paper --> ethernetalliance.org/.../WP_EA_Overview8023bt_FINAL.pdf

The VPWR minimum shutdown voltage is ~26.5 V and there is no corresponding maximum shutdown voltage. When VPWR falls below this value, the VPUV bit is set and the device enters an "undervoltage lockout" state. The absolute maximum rating for VPWR is from -0.3 V to 70 V (voltage levels beyond these values could permanently damage the device.) The recommended operating range for VPWR is from 44 V to 57 V. More information about the lockout state and VPWR ratings can be found in the TPS23880 datasheet in sections 6.1, 6.3, 6.4 (Specifications), 8.6.2.7 (Supply and Fault Event Register), and 10.2 (Power Supply Recommendations).

The datasheet can be downloaded from this page --> http://www.ti.com/product/TPS23880/technicaldocuments

Thank you for reaching out to us and don't hesitate to let us know if you have any more questions!

Aidan Davidson