AD7791,pdf datasheet (Sigma-De

The AD7791 is a low power, complete analog front end for
low frequency measurement applications. It contains a low
noise 24-bit Σ-Δ ADC with one differential input that can be
buffered or unbuffered.
The device operates from an internal clock. Therefore, the user
does not have to supply a clock source to the device. The output
data rate from the part is software programmable and can be
varied from 9.5 Hz to 120 Hz, with the rms noise equal to
1.1 μV at the lower update rate. The internal clock frequency
can be divided by a factor of 2, 4, or 8, which leads to a reduction
in the current consumption. The update rate, cutoff
frequency, and settling time will scale with the clock frequency.
The part operates with a power supply from 2.5 V to 5.25 V.
When operating from a 3 V supply, the power dissipation for
the part is 225 μW maximum. It is housed in a 10-lead MSOP.