**The AD582KH: A Comprehensive Guide to the Sample-and-Hold Amplifier**

In the world of precision analog electronics, accurately capturing a rapidly changing voltage signal at a specific instant in time is a fundamental challenge. This is where the **sample-and-hold amplifier (SHA)** becomes an indispensable component. Among the iconic devices in this category, the **AD582KH from Analog Devices** stands out as a classic, high-performance solution that has proven its reliability in countless data acquisition systems.

A sample-and-hold amplifier performs two primary functions. First, in **"sample" mode**, it tracks an input analog signal as quickly and accurately as possible. Upon receiving a "hold" command, it switches to its second function: **maintaining a constant output voltage** that is equal to the input voltage at the exact instant the command was received. This frozen voltage can then be digitized by an analog-to-digital converter (ADC) at a leisurely pace without the fear of the signal changing during the conversion process.

The AD582KH is a monolithic SHA that integrates all critical components on a single chip: a high-performance operational amplifier, a low-leakage analog switch, and a **high-quality junction field-effect transistor (JFET)** input buffer amplifier. This integration eliminates the need for external components and simplifies design. The "KH" suffix typically denotes a specific temperature grade and package type, often a hermetically sealed ceramic package suitable for extended industrial or military temperature ranges.

**Key Features and Performance Highlights**

The AD582KH is engineered for excellence, boasting several characteristics that make it a preferred choice for demanding applications:

* **Fast Acquisition Time:** One of its most critical specs, the AD582KH can acquire a 10V input step to within 0.01% accuracy in just **6 microseconds**. This speed is crucial for capturing high-frequency signals.

* **Low Droop Rate:** In hold mode, the captured voltage is stored on an external capacitor. The AD582KH exhibits an exceptionally **low droop rate of 0.5 mV per millisecond** (with a 1,000 pF hold capacitor), meaning the voltage changes very little over time, ensuring accuracy during the ADC's conversion cycle.

* **High Accuracy:** The device offers **low nonlinearity and minimal gain error**, ensuring that the output is a faithful representation of the sampled input.

* **Versatility:** It can be configured for a wide range of gains (including unity gain) using external resistors, making it adaptable to various signal levels.

**Typical Applications**

The primary application for the AD582KH is in high-speed data acquisition systems, where it acts as the critical interface between a sensor or signal source and a successive-approximation register (SAR) ADC. It is also found in:

* Precision instrumentation and measurement systems

* Digital signal processing (DSP) front-ends

* Pulse and radar systems

* Autocalibration circuits for multiplexed systems

**Design Considerations**

Using the AD582KH effectively requires careful attention to a few details. The choice of the **external hold capacitor (C_HOLD)** is paramount. It must be a high-quality, low-dielectric-absorption type, such as polypropylene or Teflon. Its value is a trade-off: a larger capacitor reduces droop rate but increases acquisition time. Proper grounding and bypassing are essential to maintain the device's high performance and prevent noise from degrading the signal integrity.

ICGOOODFIND: The **AD582KH** remains a benchmark for monolithic sample-and-hold amplifiers, offering an exceptional blend of **speed, accuracy, and hold-mode stability**. Its integrated design simplifies system architecture, making it a robust and reliable choice for engineers designing high-performance data conversion systems where capturing a precise signal snapshot is non-negotiable.

**Keywords:**

Sample-and-Hold Amplifier (SHA)

Data Acquisition

Acquisition Time

Droop Rate

Hold Capacitor