The DACx300x have four digital IO pins that include I²C, SPI, PMBus, and GPIO interfaces. These devices automatically detect I²C and SPI protocols at the first successful communication after power-on, and then connect to the detected interface. After an interface protocol is connected, any change in the protocol is ignored. The I²C interface uses the A0 pin to select from among four address options. The SPI interface is a 3-wire interface by default. No readback capability is available in this mode. The GPIO pin can be configured in the register map and then programmed in to the NVM as the SDO pin. The SPI readback mode is slower than the write mode. The programming interface pins are:

• I²C: SCL, SDA, A0
• SPI: SCLK, SDI, SYNC, SDO/GPIO

The GPIO can be configured as multiple functions other than SDO. These are LDAC, PD, STATUS, PROTECT, FAULT-DUMP, and RESET. All the digital pins are open-drain when used as outputs. Therefore, all the output pins must be pulled up to the desired IO voltage using external resistors.