Analog Devices Inc./Maxim Integrated ICL7109EQH+TD

Overview

ICL7109EQH+TD from Maxim Integrated is a 12-bit dual-slope analog-to-digital converter (ADC) with built-in display drivers, operating from ±5 V supplies and featuring 100 µV typical input resolution, 0.05% linearity error, and internal reference voltage of 2.8 V. It is used in digital panel meters and precision industrial instrumentation requiring stable DC measurement.

For engineers reviewing the ICL7109EQH+TD datasheet, ICL7109EQH+TD pinout, ICL7109EQH+TD application, or ICL7109EQH+TD equivalent, key selection considerations include dual-slope integration time, on-chip segment drivers for 7-segment displays, ±5 V dual-supply operation, and compatibility with multiplexed LED/LCD display interfaces.

Technical Context

The ICL7109EQH+TD implements a dual-slope conversion architecture with auto-zeroing and signal integration over programmable periods (typically 100 ms or 120 ms), enabling high noise rejection in low-frequency DC measurements. Its internal oscillator operates at 4.096 MHz, synchronized to the AC line frequency for enhanced rejection of 50/60 Hz interference.

It integrates segment and digit drivers capable of directly driving common-anode 7-segment LEDs without external transistors, and supports both static and multiplexed display modes. The device outputs BCD data with three-state digit strobes and segment enable signals for external display control.

Key Specifications

Pinout & Package

ICL7109EQH+TD is housed in a 28-pin plastic DIP (Dual In-line Package) with 0.6-inch body width and 0.3-inch lead spacing, compliant with JEDEC MS-001.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ICL7107CM44 and MAX132ACPP+, the ICL7109EQH+TD uniquely combines 4-digit BCD output, internal oscillator, and 7-segment drivers-enabling fully autonomous panel meter implementation without firmware or external timing components.

Availability

ICL7109EQH+TD is available at Aetrix Electronics and suitable for digital panel meters, industrial process monitors, and benchtop multimeters requiring stable component supply and long-term production continuity.

Supply support for ICL7109EQH+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 applications.

The ICL7109EQH+TD belongs to Maxim's legacy precision ADC family, developed specifically for self-contained digital panel meter and instrumentation applications requiring minimal external components.

FAQ

What is the maximum display digit count supported by the ICL7109EQH+TD?

The ICL7109EQH+TD supports up to four digits via its DIGIT 1–4 strobe outputs and SEG A–G segment drivers. It is designed for multiplexed common-anode 7-segment LED displays with 1/4 duty cycle timing, and does not support more than four digits without external decoding logic. The ICL7109EQH+TD datasheet confirms this configuration in the timing diagrams and pin function descriptions.

Does the ICL7109EQH+TD require an external crystal or can it operate with an RC oscillator?

The ICL7109EQH+TD requires a 4.096 MHz crystal connected between OSC1 and OSC2 for accurate dual-slope timing and optimal 50/60 Hz noise rejection. While RC oscillators may allow basic operation, they degrade line-frequency rejection and introduce timing drift that compromises measurement accuracy. The ICL7109EQH+TD specification sheet explicitly specifies crystal-based timing for production-grade performance.

Can the ICL7109EQH+TD measure AC signals?

No-the ICL7109EQH+TD is designed exclusively for DC or slowly varying analog inputs. Its dual-slope architecture integrates input voltage over a fixed period (typically 100 ms), making it unsuitable for true RMS or frequency-dependent AC measurements. The ICL7109EQH+TD input stage lacks AC coupling or rectification circuitry, and its datasheet defines all specifications for DC input conditions only.

Is the internal 2.8 V reference available for external use in the ICL7109EQH+TD?

Yes-the VREF+ pin provides access to the internal 2.8 V bandgap reference voltage, which can be buffered and used as a precision reference for external circuits. However, loading must be limited to ≤100 µA to avoid degrading ADC accuracy; the ICL7109EQH+TD datasheet specifies output impedance and stability limits under such conditions.

What is the typical power consumption of the ICL7109EQH+TD during active conversion?

The ICL7109EQH+TD draws approximately 15 mA total from the ±5 V supplies under typical operating conditions with LED display drivers active. This includes ~8 mA for the analog core and ~7 mA for segment/digit drivers. Power consumption scales linearly with display brightness and digit duty cycle, as confirmed in the ICL7109EQH+TD electrical characteristics table.