WIZnet Components

Yes — the market contains remarked W5100 dies relabeled as W5500 and outright clone parts with incomplete stack implementations. Verification is straightforward: read the version register (address 0x0000) over SPI — a genuine W5500 returns 0x04, while a W5100 returns 0xFF or fails to respond in W5500 mode. We run this check plus a full socket stress test (8 simultaneous TCP connections, ping throughput) on every incoming lot and ship with WIZnet-authorized packaging and traceability.

Both implement hardware TCP/IP over SPI, but the W5500 is the better part in every dimension: 8 hardware sockets vs 4, higher SPI clock support (up to 80 MHz vs ~33 MHz effective), configurable buffer allocation per socket, Wake-on-LAN, and significantly lower active power. The W5100 lives on through Arduino Ethernet Shield legacy; for new designs choose W5500. Note the two are register-incompatible — W5100 sketches need the WIZnet W5500 library (or the Arduino Ethernet library update) to run on W5500 hardware.

Yes — WIZnet Co., Ltd. was founded in 2001 in South Korea, maintains its own R&D center in Seongnam, and has shipped hundreds of millions of hardware-TCP/IP chips. The company supplies the chips used in Arduino's official Ethernet products and maintains global distribution through Mouser, Digi-Key and WPG. WIZnet is the original inventor of the hardware TCP/IP concept; "W5500" parts not traceable to WIZnet are by definition clones or remarked stock.

WIZnet authorized channel quotes 8-12 weeks from Korea. Our Shenzhen warehouse holds W5500 chip and module stock for 1-3 day shipment on quantities under 10,000 pcs. For volume production we can arrange authorized-channel orders with WIZnet C-of-C and original moisture-barrier packaging.