Digital I/OADC
operation is possible using a subset of the digital I/Os. However, tie any
unused digital input 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 an optional digital I/O:
- 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 (only when programmed to 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
delayed-reset or a reset device connected to the
RESET pin is not necessary because the ADC
automatically resets at power on. The ADC can be reset by the RESET
command. Connect the RESET pin to the host
controller to reset the ADC by hardware.
- DRDY: The data-ready indicator
is also provided by the DOUT/DRDY pin.
CS1 must be low to use
DOUT/DRDY to provide the data-ready
function. Data-ready is also determined by polling the DRDY bit of
the STATUS0 byte. Using these alternate methods, the connection of
DRDY to the host controller is not
necessary and the pin can be left unconnected.