Q1. Which power mode should I use?
A1. Normally, the application dictates which power mode to use. Common applications for the part are smart transmitters, process control input modules and low power or battery operated instrumentation. For field transmitters, the maximum current that can be used by the complete transmitter is 4 mA when the transmitter is loop powered. Therefore, the less current consumed by the ADC, the better, as it allows more current for the processor, etc. Therefore, the AD7124-8 would be used in low power mode. For process control, current consumption is not a concern so any power mode could be used. The benefits of using the full power mode is that for a given output data rate, the rms noise is lowest in the full power mode. Also, the part supports higher output data rates in the full power mode. So, this allows the customer to increase the number of channels sampled per second for a given level of performance.