ICL7135 pdf datasheet (BCD Out

The Intersil ICL7135 precision A/D converter, with its multiplexed
BCD output and digit drivers, combines dual-slope
conversion reliability with ±1 in 20,000 count accuracy and is
ideally suited for the visual display DVM/DPM market. The
2.0000V full scale capability, auto-zero, and auto-polarity are
combined with true ratiometric operation, almost ideal differential
linearity and true differential input. All necessary active
devices are contained on a single CMOS lC, with the exception
of display drivers, reference, and a clock.
The ICL7135 brings together an unprecedented combination
of high accuracy, versatility, and true economy. It features
auto-zero to less than 10μV, zero drift of less than 1μV/oC,
input bias current of 10pA (Max), and rollover error of less
than one count. The versatility of multiplexed BCD outputs is
increased by the addition of several pins which allow it to
operate in more sophisticated systems. These include
STROBE, OVERRANGE, UNDERRANGE, RUN/HOLD and
BUSY lines, making it possible to interface the circuit to a
microprocessor or UART.