Category: interface

This section briefly reviews some of the newer data interface standards that have grown up for high-speed purposes around particular applications and have subsequently become more widely entrenched. 13.4.1 EIA-485 EIA-485 shares many similarities with EIA-422, and is widely used as the basis for in-house and industrial datacom systems. For instance, one variant of the…

When you want to connect logic signals from one piece of equipment to another, it is not sufficient to use standard logic devices and make direct gate-to-gate connections, even if they are isolated from the main system. Standard logic is not suited to driving long lines; line terminations are unspecified and noise immunity is low,…

The first rule when you want to use a varying analog voltage to generate an on/off digital signal—as distinct from an analog-to-digital conversion—is: always use either a comparator or a Schmitt-trigger gate. Never feed an analog signal straight into an ordinary TTL or CMOS gate input. The reason is that ordinary gates do not have…

The two main problems which face designers who have to integrate analog and digital circuits on the same printed circuit board (PCB) are: • preventing digital switching noise from contaminating the analog signal, and • interfacing the wide range of analog input voltages to the digital circuit. Generating analog outputs from digital signals is not usually a…