I am designing a daugther board for 9606. I was confused when I seen maximum input current to DIO is 3 mA. What does it suppossed to mean ?
I have Signal of 3.3V to input in 9606, I have used buffer IC MC14011 to maintain level of input signal. Buffer is able to provide 300 mA current. I have maintained 55 ohm characteristic impedance for the daughterboard.
Now questions are,
1. Do i need to put current limiting resistor to the circuitory ? or It's input Impdeance is enought to handle ?
2. what is input impedance for any DIO in 9606 ?
3. Can 5V input given to DIOs or 3.3V is necessary ?
Current limit of 3mA only applies when the DIO is configured to be a Digital Onput. Since the FPGA tristates/floats DIO before and during configuration, you need to use pullup or pulldown resistors on pins so they are at a known level while the DIO is floating during initial powerup or during a reconfig.