- Analog Inputs
To minimize input current leakage, connect unused analog inputs to AGND when operating the device with bipolar supplies, or connect unused inputs to AVDD when operating the device with a unipolar supply.
- Analog Outputs
A capacitor is not required for REFOUT if the internal reference or the IDAC current sources are not used. Otherwise, connect a 10-µF capacitor between REFOUT and AGND.
- Digital I/O
ADC operation is possible using only a subset of the digital I/O. Tie any unused digital inputs high or low (DVDD or DGND, as appropriate). Do not float (tri-state) the digital inputs or unpredictable operation can result. The following is a summary of digital I/O with optional connections:
- CLKIN: Tie CLKIN to DGND to operate the ADC using the internal oscillator. The internal oscillator stops operation if CLKIN is connected to DVDD, resulting in loss of ADC functionality. Connect CLKIN to an external clock source to operate with an external clock.
- START: Tie START low in order to control conversions entirely by command. Tie START high to free-run conversions when programmed to the continuous-conversion mode. Connect START to the host controller to control conversions directly by the pin.
- RESET: Tie RESET high if desired. An external RC reset on the RESET input pin is not necessary because the ADC resets at power on. The ADC can also be reset by the RESET command. Connect the RESET pin to the host controller to reset the ADC by hardware.
- DRDY: Indication of data ready is also provided by the DOUT/DRDY pin. CS1 must be low to use DOUT/DRDY in the data-ready function. The indication of data ready is also achieved by polling the DRDY bit of the STATUS0 byte. For these methods, the connection of DRDY to the host controller is not necessary and the pin can be unconnected.
Program unused GPIOs as outputs (default setting). If any GPIOs are programmed as inputs, the GPIO must not be allowed to float (unconnected), otherwise AVDD power-supply leakage current may result.