Artem Rogachev
With the publication of the new Institute of Electrical and Electronics Engineers 802.3bt standard, the power range of Power over Ethernet (PoE) loads continues to expand. If you are designing systems that provide PoE, this presents a challenge. You may need to provide 5 W of power to a low-end Internet Protocol camera or 70 W to a high-end wireless access point (WAP). An enterprise switch with 48 ports that can simultaneously support 90 W on all ports would require a 4.3-kW supply.
You probably want to enable the full functionality of the high-end WAP, but do you really want to pay for the giant power supply? Knowing the typical use case of your system, you can choose a smaller power supply that would be sufficient in most situations. But, how do you prevent the supply from overloading in the rare event that all loads draw full power?
Port power management (PPM) algorithms can come to your rescue. When a new device is plugged in, the system will only turn the device on if there is enough remaining power. A system that supports priority and exceeds its power budget will actually shut down a lower-priority load when a higher-priority load is plugged in.
At a high level, PPM is a simple concept, but it can have multiple flavors, and its implementation can be tricky. Typically, there are multiple power sourcing equipment (PSE) devices, thus requiring a central microcontroller (MCU) to manage the system. Also, the system could have slots for multiple power supplies, which can get plugged in or unplugged during operation.
TI’s FirmPSE ecosystem can give you a huge head start in implementing PPM in your end equipment by removing the burden of writing low-level code to control the PSEs. Figure 1-1 shows the evaluation board of TI’s FirmPSE, which is implemented using an MSP430™ MCU and TPS23881 PSE. TI provides a binary image that you can load directly into the MSP430F5234. You will need to write code that interfaces between the host central processing unit (CPU) and the MSP430F5234 to configure the system and monitor the port status.
TI’s ecosystem features:
To learn more about PPM and ways to reduce your power supply consider watching our FirmPSE system firmware GUI offline mode or online mode training videos.
TI PROVIDES TECHNICAL AND RELIABILITY DATA (INCLUDING DATASHEETS), DESIGN RESOURCES (INCLUDING REFERENCE DESIGNS), APPLICATION OR OTHER DESIGN ADVICE, WEB TOOLS, SAFETY INFORMATION, AND OTHER RESOURCES “AS IS” AND WITH ALL FAULTS, AND DISCLAIMS ALL WARRANTIES, EXPRESS AND IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT OF THIRD PARTY INTELLECTUAL PROPERTY RIGHTS.
These resources are intended for skilled developers designing with TI products. You are solely responsible for (1) selecting the appropriate TI products for your application, (2) designing, validating and testing your application, and (3) ensuring your application meets applicable standards, and any other safety, security, or other requirements. These resources are subject to change without notice. TI grants you permission to use these resources only for development of an application that uses the TI products described in the resource. Other reproduction and display of these resources is prohibited. No license is granted to any other TI intellectual property right or to any third party intellectual property right. TI disclaims responsibility for, and you will fully indemnify TI and its representatives against, any claims, damages, costs, losses, and liabilities arising out of your use of these resources.
TI’s products are provided subject to TI’s Terms of Sale (www.ti.com/legal/termsofsale.html) or other applicable terms available either on ti.com or provided in conjunction with such TI products. TI’s provision of these resources does not expand or otherwise alter TI’s applicable warranties or warranty disclaimers for TI products.
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2023, Texas Instruments Incorporated