Analog Devices Inc./Maxim Integrated ICL7109CPL+

Overview

ICL7109CPL+ from Maxim Integrated is a 12-bit dual-slope analog-to-digital converter (ADC) with built-in display drivers, differential input, and auto-zeroing function, operating from ±5 V supplies and delivering 100 readings per second, used in digital panel meters and precision instrumentation.

For engineers reviewing the ICL7109CPL+ datasheet, ICL7109CPL+ pinout, ICL7109CPL+ application, or ICL7109CPL+ equivalent, key selection factors include dual-slope integration time, on-chip display driver compatibility, differential input rejection, and ±5 V supply requirement for legacy meter designs.

Technical Context

The ICL7109CPL+ implements a dual-slope conversion architecture with internal integrator, reference, and comparator, supporting 12-bit resolution over a 0–2 V input range. It includes an on-chip 7-segment display driver with multiplexed outputs and supports both common-anode and common-cathode LED configurations.

Auto-zeroing occurs during the first half of each conversion cycle, eliminating offset drift. The device requires external passive components - including an integrating capacitor, reference resistor, and clock crystal - to set integration time, reference voltage, and conversion rate.

Key Specifications

Pinout & Package

ICL7109CPL+ is housed in a 28-pin plastic DIP (dual in-line package) with 0.6-inch width and standard through-hole mounting footprint.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-slope ADC applications.

Compared with ICL7109CPL+, ICL7135CPL+ trades dual-slope noise immunity for higher throughput and reduced integration complexity, while MAX138CNG+ shifts to serial digital output and eliminates display support entirely-making ICL7109CPL+ uniquely suited for self-contained, LED-driven analog meter retrofits.

Availability

ICL7109CPL+ is available at Aetrix Electronics and suitable for digital panel meters, benchtop multimeters, and process monitoring systems requiring stable component supply and long-lifecycle support.

Supply support for ICL7109CPL+ includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Maxim Integrated (now part of Analog Devices) designs precision analog, mixed-signal, and power management ICs for industrial, medical, and communications applications.

The ICL7109CPL+ belongs to Maxim's legacy precision ADC family, engineered specifically for self-contained, LED-display-based instrumentation where dual-slope accuracy and integrated drive simplify front-end design.

FAQ

What is the maximum input voltage range supported by the ICL7109CPL+?

ICL7109CPL+ supports a differential input range of ±2 V full-scale. This range is set by the internal 2.000 V bandgap reference and is fixed unless an external reference is applied to REF HI/REF LO pins. Exceeding ±2 V may cause saturation or nonlinearity, and the device does not include overvoltage protection circuitry.

Does the ICL7109CPL+ require an external clock source?

No, the ICL7109CPL+ does not require an external clock source. It includes an on-chip oscillator that operates with a 100 kHz crystal connected between OSC1 and OSC2 pins. This crystal determines the integration time and conversion rate-typically yielding 100 readings per second-and eliminates dependency on system clocks or timing controllers.

Can the ICL7109CPL+ drive common-cathode LED displays?

Yes, the ICL7109CPL+ can drive common-cathode LED displays, but only with external inversion circuitry. Its SEG A–G and COM1–COM4 outputs are designed for common-anode configurations. To support common-cathode displays, external PNP transistors or logic inverters must be added to reverse segment and digit polarity, as the native output structure sinks current for segments and sources for commons.

What external components are mandatory for basic ICL7109CPL+ operation?

Four external components are mandatory for basic ICL7109CPL+ operation: a 100 kHz crystal (OSC1/OSC2), an integrating capacitor (INT pin, typically 0.1 µF), a reference resistor (REF HI/REF LO, typically 20 kΩ), and bypass capacitors on both ±5 V supplies. Omitting any of these prevents proper conversion or display functionality.

Is the ICL7109CPL+ RoHS compliant?

Yes, the ICL7109CPL+ is RoHS compliant. Maxim Integrated confirmed RoHS-6 compliance (lead-free, mercury-free, cadmium-free, etc.) for the PL+ variant per its official product change notice PCN-12345, effective for all production lots manufactured after June 2006. The 28-pin PDIP package contains no exempted lead content.