W5500 Ethernet shield is designed using the WIZnet W5500 chip. Please click the link for the further information about W5500. It supports both 3.3V & 5V. This Ethernet Shield is compatible with Arduino and ARM mbed Platform.
W5500 Ethernet shield has several configurable GPIOs
Caution) When the user uses 5V Platform, we cannot confirm a stable operation of SD-CARD. Therefore, though 5V Platform is safe to use after going through enough tests, it is highly recommended to mount buffer & 100nF Capacitor for a secure operation.
There is a W5500 inside W5500 Ethernet shield. Therefore SPI operation & Timing Diagram of Ethernet shield follows one of W5500. For more information about W5500 chip please also refer to the chip's datasheet:
Rev 1.0 Schematic
Rev 1.01_Customize Schematic
Using WIZnet Ethernet Library for ioshield-A
WizWiki Forum : WIZnet Forum for Technical support and Project shared
WIZ550io and ioShield-A for Arduino : Releated Products
http://wizwiki.net/jp : WIZnet Japanese Blog