Using the Single-Wire Interface allows the connection of ATECC608A-TFLXTLS to a host using only a single pin (SDA) to transfer data in both directions. This interface does not use the SCL pin which is configured as a GPIO output.
To prevent forward biasing the internal diode and drawing current across power planes in the system, the resistor pull-up on the SDA pin should either be connected to the same supply that is connected to the VCC pin or to a lower voltage rail.
Since the ATECC608A-TFLXTLS is configured for a fixed I/O level the signal levels of the SDA signal may be different than the VCC voltage level. This situation might occur if the ATECC608A-TFLXTLS device is physically distant from the bus master device and the supply voltage for the bus master is different than the supply voltage for ATECC608A-TFLXTLS.
