The Intersil ICL7135 precision A/D converter, with its
multiplexed BCD output and digit drivers, combines dualslope 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 autopolarity 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.

Features
• Accuracy Guaranteed to ±1 Count Over Entire ±20000
Counts (2.0000V Full Scale)
• Guaranteed Zero Reading for 0V Input
• 1pA Typical Input Leakage Current
• True Differential Input
• True Polarity at Zero Count for Precise Null Detection
• Single Reference Voltage Required
• Overrange and Underrange Signals Available for AutoRange Capability
• All Outputs TTL Compatible
• Blinking Outputs Gives Visual Indication of Overrange
• Six Auxiliary Inputs/Outputs are Available for Interfacing to
UARTs, Microprocessors, or Other Circuitry
• Multiplexed BCD Outputs
• Pb-Free Plus Anneal Available (RoHS Compliant)