4 1/2 Digit ADC with Multiplexed BCD Outputs


The Maxim ICL7135 is a high precision monolithic 41/2 digit A/D converter. Dual slope conversion reliability is combined with ±1 in 20,000 count accuracy and a 2.0000V full scale capability. It features high impedance differential inputs, nearly ideal differential linearity, true ratiometric operation, auto zero and auto-polarity. The multiplexed BCD outputs and digit drivers provide easy interface to external display drivers like the Maxim ICM7211A. The only other external components needed to make precision DVM/DPMs are a reference and a clock. For more complex systems the BCD outputs are enhanced by Active-Low STROBE, OVERRANGE, UNDERRANGE, RUN/Active-Low HOLD and BUSY lines providing easy interface to microprocessors and UARTs. This interfacing capability makes the ICL7135 an ideal device for use in microprocessor based data acquisition and control systems.

The ICL7135 has auto-zero accuracy better than 10µV, zero drift of 0.5µV/°C, input bias current of 10pA max. and rollover error of less than 1 count.

ICL7135: Typical Operating Circuit ICL7135: Typical Operating Circuit Enlarge+

Key Features

  • Improved 2nd Source (See our “Maxim Advantage™” Page 3)
  • ±20,000 Count Resolution
  • Guaranteed ±1 Count accuracy
  • Over-range, under-range signals for auto-range capability
  • Easy interface to UARTs and µPs
  • TTL compatible, Multiplexed BCD outputs
  • True differential input. Zero reading guaranteed for 0 volt Input
  • True polarity at zero for precise null detection
  • Monolithic CMOS Design


  • Current
  • Material Thickness
  • Pressure
  • Resistance
  • Speed
  • Temperature
  • Voltage
  • Weight
Part Number Resolution
Data Bus Diff/S.E. Input External VREF
External VREF
Bipolar VIN
Package/Pins Budgetary
min max max See Notes
ICL7135  20000
Diff. Only -5 5 2
$9.54 @1k
See All Display-Oriented ADCs (33)
Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

Technical Documents

Tutorial 2102 Delta-Sigma ADCs Replace Integrating ADCs for Panel Meters

Quality and Environmental Data

Request Reliability Report for: ICL7135 
Lead-Free Package Tin (Sn) Whisker Reports

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