The evolution of the RS-232 transceiver(RS232收发器开发)
Abstract: RS-232 transceivers have been integral to RS-232 designs for more than two decades. This application note reviews the history of the RS-232 transceiver. It traces technical advances and explains the practical benefits for diverse applications. Various Maxim devices are cited as industry-leading examples of the RS-232 transceiver evolution.
Introduction
Over the last 25 years, RS-232 transceivers have been modified to address the changing trends in RS-232 designs. Innovations have included integrated charge pumps, high-ESD protection, AutoShutdown™, a 3.3V single supply, higher bandwidth, a level translator, and shrinking packages. These many improvements have enhanced functionality, simplified the RS-232 interface, reduced component count, and saved space. One of the leaders in RS-232 transceiver innovations, Maxim Integrated Products, offers over 158 RS-232 devices with value-added features that address a wide range of applications.
This application note reviews key RS-232 transceiver features. Viewed in chronological order, the evolution of the RS-232 transceiver also reflects changing demands for serial communications.
Background
The EIA/TIA-232-E standard was introduced in 1962, and has since been updated four times to meet the evolving needs of serial communication applications. The official name of the EIA/TIA-232-E standard is "Interface Between Data Terminal Equipment (DTE) and Data Circuit-Termination Equipment (CTE) Employing Serial Binary Data Interchange." There is a more simple definition: serial data communication between a host system (DTE) and a peripheral system (CTE) (Figure 1).
Figure 1. Illustration of a DTE to DCE system. The application features the MAX214 transceiver and shows two PCs with DTE and DCE operation.
History of applications
Historically, RS-232 serial communication was used to interface computers to peripherals such as modems, printers, keyboards, joysticks, and a mouse. Most of these applications have now converted to other communication protocols such as the universal serial bus (USB).
Today, RS-232 serial communication is used in applications such as GPS, POS, glucose meters, barcode scanners, automotive telematics, set-top boxes, gaming, and many others that require low-cost, low-speed (sub 1Mbps) serial communication.