there is a problen with chip W5500. It works good but unpredictably it goes to “bad state” - chip is very hot and it has a high current consumption.
In bad state chip stays until power supply is switched off. By deeper exploration, I have come to the conclusion that there is no need to turn off all power. It is sufficient to shut down the AVDD power supply (pins 4, 8, 15, 17, 21) and it is not necessary to shut down the VDD (pin 28).
W5500 does not going out from bad state even by external reset (pin 37) or by PHY reset (through PHYCFGR) or S/W reset (through MR).
In normal state the external reset, PHY reset and S/W reset is functional (I have verified this for example by changing speed, duplex, etc).
W5500 behaviour in bad state:
- case temperature of W5500 is about 100 degrees Celsius (at ambient temperature 25)
- current to pins 4, 8, 15, 17, 21 (AVDD) is in summary around 700mA
- SPI communication with STM32L071 is OK (I can read/write W5500 registers)
- sometimes LINK LED blinks, but connection to LAN is immposible
It is not a problem with just one chip, but it has become a few chips (10 pcs) of about 100 pieces that are in operation.
I have made several changes to the W5500 operating setting and it seems that these changes have helped and accidents are no longer over (set 10Mb, half duplex, wait states within PHY reset).
But when the chip is in bad state, I don’t know how to set it to normal state.
Why does only power off work?
What could be the cause of this bad state?