W5500 Overheating


Has anyone had any problems with the W5500 overheating and then shutting down/restarting?

I have a couple of embedded devices where I have built a web interface. I’m polling the socket status registers in a loop, and I have found that if I poll them too often, the chip overheats and shuts down for a few seconds. Then, once it cools, if I reset it (pulling RESET low), it will come back to life. I thought I killed it for a while, but they are tough little chips.

This has shown up on two different prototype circuit boards with slightly different PHY hardware implementations. One uses a HanRun mag-jack, and the other an external transformer. Both are built directly from the reference designs. My current limiters for the link/speed/act LEDs are 360 ohms, so there shouldn’t be an issue with too much current. I’ve tested 5 different W5500’s from two different batches.

Can anyone from WIZNet comment on whether there is a spec on how often the status register can be read? If I get the poll rate down around 100 times a second or less, the temperature stays below 50 degrees C. If I go over 1000 polls per second, the chip starts overheating. I’m running my SPI bus clock at 16MHz.

For now, setting a timer to slow down polling seems to solve the problem, but the performance of the web interface suffers quite a bit.

Any help or comments would be appreciated.