We have three LM4550B codecs with the SDATA_OUT lines chained together and driven from an FPGA pin.
When the FPGA pin drive strength is set to 2mA, we get a very rounded square wave and on about 1% of boards the codecs will occasionally fail to initialize correctly. If we increase the drive strength to 4mA the problem goes away.
Is there data on the current consumption of the SDATA_OUT input? We'd like to get some hard numbers on why the problem is occurring.
Regards,
Glenn