Class 5 PoE PD (12 V/2.5 A) supply reference design with smooth transition to auxiliary


Design files


This reference design implements an IEEE802.3bt compliant Class 5 Power over Ethernet (PoE) Powered Device (PD) with smooth transition between the PoE input and an auxiliary supply connected to the output.  The design consists of a 12-V/2.5-A active clamp forward converter utilizing the UCC2897A controller and allows one PoE Power Source Equipment (PSE) supply and one AC/DC wall adapter auxiliary supply to be used in order to decrease the probability of power and data loss in your system.  An IEEE802.3bt compliant TPS2373-4 high power PD controller is utilized to control all PoE functions.

In need of an IEEE802.3bt-ready PSE controller? Check out the TPS23881.

  • Smooth transition when switching between PoE input and 12-V adapter on output
  • 89% efficiency with 12-V/2.5-A output and PoE input (FET OR-ing)
  • Diode OR-ing option for lower cost
Output voltage options PMP21103.1
Vin (Min) (V) 42.5
Vin (Max) (V) 57
Vout (Nom) (V) 12
Iout (Max) (A) 2.5
Output Power (W) 30
Isolated/Non-Isolated Isolated
Input Type DC
Topology Forward- Active Clamp^POE
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A fully assembled board has been developed for testing and performance validation only, and is not available for sale.

Design files & products

Design files

Download ready-to-use system files to speed your design process.

TIDT081.PDF (2893 K)

Test results for the reference design, including efficiency graphs, test prerequisites and more


Detailed schematic diagram for design layout and components


Complete listing of design components, reference designators, and manufacturers/part numbers


Detailed overview of design layout for component placement

TIDRYT9.ZIP (4238 K)

Files used for 3D models or 2D drawings of IC components

TIDCF94.ZIP (1637 K)

Design file that contains information on physical board layer of design PCB

TIDRYT8.PDF (1647 K)

PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

AC/DC & DC/DC controllers (external FET)

UCC2897A110-V active clamp current mode PWM controller with P-channel clamp FET and line OV protection

Data sheet: PDF | HTML

CSD18534Q5A60-V, N channel NexFET™ power MOSFET, single SON 5 mm x 6 mm, 9.8 mOhm

Data sheet: PDF | HTML

CSD19538Q2100-V, N channel NexFET™ power MOSFET, single SON 2 mm x 2 mm, 59 mOhm

Data sheet: PDF | HTML

CSD25402Q3A-20-V, P channel NexFET™ power MOSFET, single SON 3 mm x 3 mm, 8.9 mOhm

Data sheet: PDF | HTML
Powered devices

TPS2373IEEE 802.3bt PoE high-power PD interface with advanced startup

Data sheet: PDF | HTML
Shunt voltage references

TL431Adjustable precision shunt regulator

Data sheet: PDF | HTML
Supervisor & reset ICs

TPS3803Low-power voltage detector

Data sheet: PDF

Technical documentation

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Type Title Date
* Test report Class 5 PoE PD (12 V/2.5 A) supply reference design with smooth transition Jan. 25, 2019

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