Ethernet Controller Overview

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This is a W5500 Ethernet controller reference design with PoE-related power circuitry.
In plain English: it lets another controller, like an Arduino, STM32, ESP32, or Raspberry Pi header, talk to a wired Ethernet network over SPI. The W5500 handles the Ethernet protocol/PHY side, the RJ45 connector connects to the Ethernet cable, the 25 MHz crystal clocks the Ethernet chip, and the AMS1117-3.3 regulator generates the 3.3 V rail for the W5500 and logic.
Diagram



  
    
  
  
    
  
















"12V Input Jack"
"AMS1117-3.3 Regulator"
"3.3V Power Rail"
"W5500 Ethernet Controller"
"25MHz Crystal"
"2x4 SPI Header"
"RJ45 Ethernet Connector"
"Link and Activity LEDs"
Key blocks:
  • J3 barrel jack / +12V rail: external DC input.
  • U2 AMS1117-3.3: converts input power down to 3.3 V.
  • U1 W5500: Ethernet controller with SPI interface.
  • J1 RJ45 connector: physical Ethernet port.
  • J2 2x4 header: exposes SPI/control signals like SCLK, MOSI, MISO, SCS, RST, and INT.
  • X1 crystal + capacitors: provides the clock needed by the W5500.
  • LED/resistor networks: link/activity/power indication and Ethernet termination/biasing.
One important note: the project description says “PoE” and “can be used as PoE injector,” but from the visible component list this looks more like an Ethernet/W5500 board with 12 V input and RJ45 circuitry, not a complete standards-compliant IEEE 802.3af/at PoE injector or powered-device supply. A real PoE injector/PD usually needs dedicated PoE magnetics, detection/classification, isolation, and power-path circuitry.
Check PoE nets
ESP32 wiring
Check W5500 support
Review PoE BOM
Explain power path
ACTLED
RDP
RCT
RDN
TCT
TDN
TDP
LINKLED
C4
Capacitance
10nF
+3V3A
+3V3A
+3V3A
C3
Capacitance
6.8nF
+12V
C2
Capacitance
6.8nF
C7
Capacitance
4.7uF
C6
Capacitance
10nF
C5
Capacitance
22nF
R3
Resistance
33 Ω
R4
Resistance
49.9 Ω
U1
R5
Resistance
1kΩ
R6
Resistance
12.4kΩ
  • Generic Inductor
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  • Generic Resistor
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    RMCF0805JT47K0
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    CTL1206FYW1T
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    1070TR
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W5500 PoE Project

W5500 PoE Project thumbnail
10/100 Base-T/TX PHY Ethernet controller that supports PoE with SPI Interface. Based on W5500. Can be used as PoE injector. #project #referenceDesign #template #w5500 #PoE #EtherNet #RJ5

Properties

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