Class 2 Mulitple Output, High Efficiency Flyback Converter for PoE Applications


Design files


This reference evaluation module, featuring the TPS23785B PoE interface and DC-toDC contoller, is used for class 2 PoE applications where high effliency and multiple outputs are required.

The flyback converter with synchronous reftifier provides excellent efficiency and small size for PoE applications such as IP phones. The TPS23785B contains both the PoE powered device and the PWM contoller.

  • Efficiency achieved >90%
  • 1.5% peak to peak cross regulation on 5V
  • Isolated multiple output (3.3V at 0.88A; 5V at 0.35A; 10V at 0.11A)
  • Uses TPS23785B high-power, high-efficiency PoE PD and DC-to-DC controller
  • Small board size
  • This circuit design is fully functional and tested and recommended for new design.
Output voltage options PMP8407.1 PMP8407.2 PMP8407.3
Vin (Min) (V) 36 36 36
Vin (Max) (V) 57 57 57
Vout (Nom) (V) 3.3 5 10
Iout (Max) (A) .88 .35 .11
Output Power (W) 2.904 1.75 1.1
Isolated/Non-Isolated Isolated Isolated Isolated
Input Type DC DC DC
Topology Flyback- Synchronous^POE Flyback- Synchronous^POE Flyback- Synchronous^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.


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

SLURA15.PDF (61 K)

Detailed schematic diagram for design layout and components

SLURA16.PDF (121 K)

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

SLUC423.ZIP (313 K)

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


PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

N-channel MOSFETs

CSD17527Q5A30-V, N channel NexFET™ power MOSFET, single SON 5 mm x 6 mm, 10.8 mOhm

Data sheet: PDF
Powered devices

TPS23785BHigh-Power, High-Efficiency PoE PD and DC-to-DC Controller

Data sheet: PDF
Shunt voltage references

TLV431A1% accuracy, low-voltage, adjustable precision shunt regulator

Data sheet: PDF | HTML

Technical documentation

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Type Title Date
* Test report PMP8407 Test Results Sep. 16, 2013

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