Microchip TC7107ACKW: A Detailed Look at a Classic 3-1/2 Digit Analog-to-Digital Converter

The Microchip TC7107ACKW stands as a seminal integrated circuit in the history of data acquisition, a precision 3-1/2 digit analog-to-digital converter (ADC) specifically engineered for driving common anode light-emitting diode (LED) displays. This device consolidates all the necessary functions for a digital measurement system into a single 40-pin package, offering a complete, low-power solution for converting analog signals into a highly readable digital format.

Core Architecture and Functionality

The TC7107ACKW is built around a dual-slope integration conversion technique. This method is renowned for its exceptional accuracy and outstanding noise rejection, particularly of 50Hz or 60Hz line cycle interference, making it ideal for industrial and laboratory environments. The IC integrates a complete ADC system, including a reference voltage source, a clock oscillator, a precision differential input comparator, and the necessary decoding and digit drivers for a seven-segment display.

The "3-1/2 digit" specification signifies a display range from -1999 to +1999 counts. The most significant digit (MSD) is the "half digit," capable of displaying only a '1' or is blank, providing the 2000-count range. The device offers automatic zero correction and true polarity indication, always displaying the correct sign (+ or -) on the LED readout. A key feature of the TC7107ACKW is its ability to directly drive common anode LED displays without the need for external transistors, simplifying design and reducing board space and component count.

Key Features and Specifications

Complete ADC System: Integrates all analog and digital functions on a single chip.

High Accuracy: Features ±1 count accuracy ensuring no missing codes over the full temperature range.

Low Power Consumption: Typically draws less than 10mA, suitable for portable and benchtop instruments.

Direct LED Drive: Includes seven-segment decoders, digit drivers, and a polarity indicator for directly interfacing with common anode LED displays.

Differential Input and Reference: The high-impedance differential input allows for ratiometric measurements and rejection of common-mode noise.

Low Noise & Auto-Zero: A typical noise level of 15µV and an auto-zero cycle ensure stable readings.

Typical Applications

The TC7107ACKW is perfectly suited for applications requiring a clear, direct digital readout. Its most classic application is in digital panel meters (DPMs) for measuring voltage, current, or resistance. It is also widely found in:

Digital thermometers and multimeters

Weigh scales and strain gauge readouts

Process control indicators

Automotive diagnostic equipment

ICGOODFIND Summary

The Microchip TC7107ACKW remains a highly reliable and effective solution for designing straightforward digital readout systems. Its unparalleled integration, which eliminates the need for external display drivers, combined with the noise-immune dual-slope architecture, makes it a timeless choice for engineers developing cost-effective, high-performance panel meters and measurement equipment. While newer sigma-delta ADCs offer higher resolution, the TC7107ACKW excels in simplicity and display interface elegance.

Keywords:

1. Analog-to-Digital Converter (ADC)

2. Dual-Slope Integration

3. LED Display Driver

4. 3-1/2 Digit

5. Digital Panel Meter (DPM)