Zero Reading for 0-V Input
Precision Null Detection With True Polarity
at Zero
1-pA Typical Input Current
True Differential Input
Multiplexed Binary-Coded-Decimal (BCD)
Output
Low Rollover Error: ±1 Count Max
Control Signals Allow Interfacing With
UARTs or Microprocessors
Autoranging Capability With Over-and
Under-Range Signals
TTL-Compatible Outputs
Second Source to Teledyne TSC7135,
Intersil ICL7135, Maxim ICL7135, and
Siliconix Si7135
CMOS Technology

DESCRIPTION
The ICL7135C and TLC7135C converters are manufactured with Texas Instruments highly efficient CMOS
technology. These 4 1/2-digit, dual-slope-integrating, analog-to-digital converters (ADCs) are designed to
provide interfaces to both a microprocessor and a visual display. The digit-drive outputs D1 through D4 and
multiplexed binary-coded-decimal outputs B1, B2, B4, and B8 provide an interface for LED or LCD
decoder/drivers as well as microprocessors.
The ICL7135C and TLC7135C offer 50-ppm (one part in 20,000) resolution with a maximum linearity error of
one count. The zero error is less than 10 μV and zero drift is less than 0.5 μV/°C. Source-impedance errors are
minimized by low input current (less than 10 pA). Rollover error is limited to ±1 count.
The BUSY, STROBE, RUN/HOLD, OVER RANGE, and UNDER RANGE control signals support
microprocessor-based measurement systems. The control signals also can support remote data acquisition
systems with data transfer through universal asynchronous receiver transmitters (UARTs).
The ICL7135C and TLC7135C are characterized for operation from 0°C to 70°C.