The AD7798/AD7799 are low power， low noise， complete analog front ends for high precision measurement applications. The AD7798/AD7799 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 27 nV for the AD7799 and 40 nV for the AD7798 when the update rate equals 4.17 Hz. On-chip features include a low-side power switch， reference detect， programmable digital output pins， burnout currents， and an internal clock oscillator. The output data rate from the part is software-programmable and can be varied from 4.17 Hz to 470 Hz. The part operates with a power supply from 2.7 V to 5.25 V. The AD7798 consumes a current of 300 μA typical， whereas the AD7799 consumes 380 μA typical. Both devices are housed in a 16-lead TSSOP package.