AD7793

The AD7792/AD7793 is a low power, complete analog front end for low frequency measurement applications. The AD7792/AD7793 contains a low noise 16/24-bit -∆ ADC with three differential analog inputs. The on-chip low noise instrumentation amplifier means that signals of small amplitude can be interfaced directly to the ADC. With a gain setting of 64, the rms noise is 80 nV when the update rate equals 16.6 Hz.

The device contains a precision low noise, low drift internal bandgap reference for absolute measurements. An external reference can also be used if ratiometric measurements are required. On-chip programmable excitation current sources can be used to supply a constant current to RTDs and thermistors while the 100 nA burnout currents can be used to ensure that the sensors connected to the ADC are not burnt out. For thermocouple applications, the on-chip bias voltage generator steps up the common mode voltage from the thermocouple so that is within the ADC's allowable range.

The device can be operated with the internal clock or, alternatively, an external clock can be used if synchronizing several devices. The output data rate from the part is software programmable and can be varied from 4 Hz to 500 Hz.

The part operates with a power supply from 2.7 V to 5.25 V. It consumes a current of 450 uA maximum and is housed in a 16- lead TSSOP package.