HI-7159A pdf datasheet (Microp

The Intersil HI-7159A is a monolithic A/D converter that uses
a unique dual slope technique which allows it to resolve input
changes as small as 1 part in 200,000 (10μV) without the use
of critical external components. Its digital autozeroing feature
virtually eliminates zero drift over temperature. The device is
fabricated in Intersil’ proprietary low noise BiMOS process,
resulting in exceptional linearity and noise performance. The
HI-7159A’s resolution can be switched between a high
resolution 200,000 count (51/2 digit) mode, and a high speed
20,000 count (41/2 digit) mode without any hardware
modifications. In the 41/2 digit uncompensated mode, speeds
of 60 conversions per second can be achieved. The HI-7159A
is designed to be easily interfaced with most microprocessors
through either of its three serial and one parallel interface
modes. In the serial modes, any one of four common baud
rates is available.