1 Introduction

Understanding the analog-to-digital converter (ADC) data-sheet power-supply parameters can help you design more reliable precision data acquisition (DAQ) systems. Specifically, it is important to understand that current consumption in an ADC data sheet is an average value specified at steady-state operating conditions. These measured current values therefore do not characterize transient current demand, even though ADC transient currents can be orders of magnitude larger than the specified ADC current. Transient currents can occur when transitioning between different ADC modes of operation and are most significant when initially powering the device. Moreover, the circuitry and components surrounding the ADC can cause additional transient current demand.

This article delves into the topic of ADC transient current demand by first introducing how a typical ADC data sheet specifies current, and then sharing the results of several tests that quantify transient current demand under different operating conditions. Multiple power-supply configurations that can source both average and transient currents are discussed, and finally the effects of various power-down methods are compared.