**AD7581AQ: A Comprehensive Technical Overview of the 8-Bit CMOS ADC with 8-Channel Multiplexer**

The **AD7581AQ** represents a significant integration achievement from the era of precision mixed-signal design, combining an **8-bit successive-approximation Analog-to-Digital Converter (ADC)** with an **8-channel multiplexer** on a single monolithic CMOS chip. This device was engineered to simplify data acquisition system design by providing a complete, multi-channel sampling solution in one package, reducing component count and enhancing overall system reliability.

At the core of the AD7581AQ is its **successive-approximation register (SAR)** architecture, which offers a solid conversion rate of up to **30 kHz** and ensures 8-bit resolution with no missing codes. The integrated analog multiplexer can handle eight single-ended input signals, selected via a 3-bit address code. A key feature is its **on-chip track/hold (T/H) circuit**, which eliminates the need for an external sampling capacitor and simplifies the interface with dynamic input signals. The converter operates from a single +5V power supply and consumes very low power, a hallmark of its **CMOS construction**, making it suitable for portable and power-sensitive applications.

The digital interface is designed for straightforward connection to microprocessors. It provides tri-state output buffers, allowing the device to be directly connected to a microprocessor data bus. The conversion process is initiated by a **WRITE** pulse, and the end of conversion is signaled by the **INTR** (interrupt) output pin, facilitating easy handshake protocols.

The analog input range is typically set by an external voltage reference (**VREF**), offering design flexibility. The device's **CMOS technology** ensures high input impedance on the analog channels, minimizing the loading on sensor or signal-conditioning circuits.

Housed in a robust 28-pin ceramic DIP (CerDIP) package, the 'AQ' suffix denotes a specific military-grade temperature range, ensuring performance across extreme environmental conditions.

**ICGOOODFIND:** The AD7581AQ is a quintessential integrated data acquisition component. Its enduring value lies in its **high level of integration**, combining a multiplexer, T/H, ADC, and interface logic into a single, low-power CMOS device. This made it a foundational building block for systems in industrial control, automotive, and aerospace applications where reliability, simplicity, and multi-channel monitoring were paramount.

**Keywords:** **8-Bit ADC**, **8-Channel Multiplexer**, **CMOS Technology**, **Successive-Approximation**, **Data Acquisition System**