Analog Devices Inc./Maxim Integrated ICL7109CQH+TD

Overview

ICL7109CQH+TD from Maxim Integrated is a 12-bit dual-slope analog-to-digital converter (ADC) with built-in display drivers, differential input, and auto-zero function; it operates from ±5 V supplies, supports 100 mV full-scale input range, and delivers 10,000 counts resolution for precision panel meter applications.

For engineers reviewing the ICL7109CQH+TD datasheet, ICL7109CQH+TD pinout, ICL7109CQH+TD application, or ICL7109CQH+TD equivalent, key selection considerations include dual-slope integration time, on-chip display drive capability, differential input rejection, and ±5 V supply compatibility in legacy instrumentation designs.

Technical Context

The ICL7109CQH+TD implements a dual-slope conversion architecture with internal integrator, reference, and comparator, enabling high noise immunity and stable DC measurement. It includes on-chip segment and digit drivers capable of directly driving common-anode 7-segment LED displays without external transistors.

Conversion is controlled by an internal 4.096 MHz oscillator and supports programmable integration periods (100 ms, 10 ms, or 1 ms), with automatic zero calibration before each conversion cycle to eliminate offset drift.

Key Specifications

Pinout & Package

ICL7109CQH+TD is housed in a 28-pin ceramic DIP (Dual In-line Package) with 0.6-inch body width and 0.3-inch lead spacing, rated for operation from 0°C to +70°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ICL7109CQH+TD, ICL7129CQH+ offers enhanced resolution and temperature range while maintaining drop-in compatibility; MAX132ACPP+ provides superior resolution but removes integrated display functionality, shifting system complexity to firmware and external hardware.

Availability

ICL7109CQH+TD is available at Aetrix Electronics and suitable for industrial panel meters, portable multimeters, and benchtop power supply displays requiring stable component supply and long-lifecycle support.

Supply support for ICL7109CQH+TD 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 systems.

The ICL7109CQH+TD belongs to Maxim's legacy precision ADC product line, developed specifically for cost-sensitive, high-stability panel meter and instrumentation applications requiring integrated display control.

FAQ

What is the operating temperature range for the ICL7109CQH+TD?

The ICL7109CQH+TD is specified for operation from 0°C to +70°C. This commercial-grade temperature range aligns with its target use in indoor industrial panel meters and benchtop test equipment. The device uses internal auto-zero and bandgap reference circuits to maintain accuracy across this range without external calibration. ICL7109CQH+TD does not support extended or military temperature grades.

Does the ICL7109CQH+TD require an external crystal oscillator?

Yes, the ICL7109CQH+TD requires a 4.096 MHz crystal connected between OSC1 and OSC2 pins to establish precise integration timing. This frequency enables exact 100 ms, 10 ms, or 1 ms integration periods for optimal 50/60 Hz noise rejection. While some variants support RC timing, the ICL7109CQH+TD datasheet specifies crystal dependency for guaranteed accuracy. ICL7109CQH+TD cannot operate reliably with RC timing alone.

Can the ICL7109CQH+TD drive common-cathode LED displays?

No, the ICL7109CQH+TD drives only common-anode 7-segment LEDs via its SEG and DIG outputs, which source current. Its output structure is incompatible with common-cathode configurations that require sinking current. Attempting to interface with common-cathode displays would require external transistor arrays or level-shifting circuitry, negating the integration benefit. ICL7109CQH+TD's display architecture is fixed to common-anode topology.

What is the maximum number of digits the ICL7109CQH+TD can drive?

The ICL7109CQH+TD supports up to four 7-segment digits plus decimal points using its four DIG outputs and seven SEG outputs. Digit multiplexing is handled internally with timing synchronized to the conversion cycle. Adding more than four digits requires external multiplexing logic or a different controller. ICL7109CQH+TD does not support alphanumeric or dot-matrix displays - only numeric 7-segment formats.

Is the ICL7109CQH+TD pin-compatible with the ICL7107 series?

No, the ICL7109CQH+TD is not pin-compatible with the ICL7107 series. Although both are dual-slope ADCs with display drivers, ICL7109CQH+TD uses a 28-pin ceramic DIP package with distinct pin assignments for display drivers, oscillator, and reference inputs. The ICL7107 uses a 40-pin DIP and lacks integrated digit drivers. Interchanging them requires PCB redesign. ICL7109CQH+TD was designed as a compact, integrated alternative-not a drop-in upgrade.