AD7720,pdf datasheet (CMOS Sig

This device is a 7th order sigma-delta modulator that converts
the analog input signal into a high speed 1-bit data stream. The
part operates from a +5 V supply and accepts a differential input
range of 0 V to +2.5 V or ±1.25 V centered about a commonmode
bias. The analog input is continuously sampled by the
analog modulator, eliminating the need for external sample and
hold circuitry. The input information is contained in the output
stream as a density of ones. The original information can be
reconstructed with an appropriate digital filter.
The part provides an accurate on-chip 2.5 V reference. A reference
input/output function is provided to allow either the internal
reference or an external system reference to be used as the
reference source for the part.
The device is offered in a 28-lead TSSOP package and designed
to operate from –40°C to +85°C.