System Description
2
SLVUBN3A – May 2019 – Revised October 2019
Copyright © 2019, Texas Instruments Incorporated
24-Port (4 Pair) Power Sourcing Equipment Reference Design for Multi-port
Applications
An IMPORTANT NOTICE at the end of this TI reference design addresses authorized use, intellectual property matters and other
important disclaimers and information.
1
System Description
This reference design provides a competitive and alternative solution.
In a multiport PSE system, the system-level software is the biggest challenge. The software handles
complicated situations and addresses the following challenges:
•
The power supply is usually not able to support all ports with a full load due to size and cost
constraints. The system software manages the port power with priority to keep the total power
consumption below the power budget.
•
There are multiple power supplies in the system. These power supplies could be in sharing mode or
backup mode. The system software shuts down low-priority ports fast enough to keep the total power
consumption below the remaining power budget.
•
There are some legacy PD devices that do not present the standard PoE PD signature. The system
software finds a way to supply power to these devices.
•
System software limits the port power based on the PD class levels or host configuration.
•
When there are load-step changes on multiple ports, the system software acts quickly enough to keep
the power consumption below the power budget.
1.1
Key System Specifications
Table 1. Key System Specifications
PARAMETER
SPECIFICATIONS
DETAILS
Input voltage
44 V–57 V
Port power limit
2 W–120 W
> 90 W is considered as nonstandard power
Compliance
IEEE 802.3bt Type 3 and Type 4
PD class level supported
Class 0 to class 8
Number of power supply supported
1–2
In sharing mode and redundant mode
Max port number supported
48
Referred to RJ45 ports
1.2
Description
This reference design features the TPS23881 daughtercard, the octal channel, the TPS23881 device, and
the IEEE802.3bt ready PoE PSE controller. When paired with the PSE motherboard PSEMTHR24-081
(sold separately) and MCU daughtercard PSEMCUDAUEVM-082 (sold separately), users can evaluate
the TPS23881 device and PSE system firmware solution.
The full PoE evaluation ecosystem includes the following:
•
PSEMTHR24EVM-081: motherboard for 24-port PoE PSE applications (sold separately)
•
PSEMCUDAUEVM-082: MSP430 daughtercard for 24-port PoE PSE applications (sold separately)
•
TPS23881EVM-083: TPS23881 daughtercard for 24 port Type 3 and Type 4 PSE applications (sold
separately)
•
USB2ANY interface adapter: used with the PSE system firmware GUI for I2C/UART interaction with
the PSEMCUDAU-082 daughtercard (sold separately)
•
MSP-FET programmer: used with Uniflash GUI for programming the MSP430 device
•
PSE system firmware code image (request access through the
or the
)
•
PSE system firmware GUI (request access through the
or the
)