I just got an Ethernet shield, but I'm having some problems. After about a minute of being powered, it gets fairly hot. The PWR light is red, but otherwise, it works fine.
I'm using an Arduino Uno with a HanRun HR911106A 10/49 shield. Is it faulty, or am I not connecting it to power correctly? It heats up both from battery power and from USB power.
Ethernet is power hungry! The ENC28J60, which is the chip that most of the Ethernet shields use, draws up to 250 mA at 3.3 V -- that's 825 mW. I've used these chips before on my own boards, and have always been surprised at how much power they draw and how warm they get. So don't worry. If you can still hold your finger on it, that's fine. If you're still concerned, measure the temperature of the chip. If it is below 70°C (158°F), it's within its normal operating range.
The ENC28J60 is built for 3.3V IO where the Arduino Uno uses 5V IO. The interface typically works fine, however you are going to be dropping 1.7V across the protection diodes of the chip. Things will get hot but if it's below the operating temperature and your not looking for 10 year reliability, it'll work fine.
