the statistical average of many conversions Stated dif ferently it is the voltage input at which the uncertainty of the conversion is

the statistical average of many conversions. Stated dif- ferently, it is the voltage input at which the uncertainty of the conversion is 50%. Code Width The distance (voltage differential) between two transition points is called the “Code Width.” Ideally the ig M INTRODUCTION This application note is intended for PIC16C7X users with some degree of familiarity with analog system design. The various sections discuss the following topics: • Commonly used A/D terminology • How to configure and use the PIC16C71 A/D • Various ways to generate external reference voltage (VREF) • Configuring the RA3:RA0 pins COMMONLY USED A/D TERMINOLOGY The Ideal Transfer Function In an A/D converter, an analog voltage is mapped into an N-bit digital value. This mapping function is defined as the transfer function. An ideal transfer is one in which there are no errors or non-linearity. It describes the “ideal” or intended behavior of the A/D. Figure 1 shows the ideal transfer function for the PIC16C7X A/D. FIGURE 1: PIC16C7X IDEAL TRANSFER FUNCTION Authors: Sumit Mitra, Stan D'Souza, and Russ Cooper Microchip Technology Inc. FFh FEh D ig ita l c od e o u tp ut Code Width (CW) 04h Using the Analog-to-D Ó 1997 Microchip Technology Inc.

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