AN654 View Datasheet(PDF) - Maxim Integrated

Part Name

Description

Manufacturer

AN654

New RS-232 ICs Feature 1µA Supply Current, ±15kV ESD Protection, and 3V Operation

Maxim Integrated 

Figure 2. The MAX3223 transceiver family combines ease of use (automatic shutdown) with the

+flexibility of override controls that force the IC into shutdown or normal operation.

DTE/DCE in One IC Eliminates Null Modem

Also useful for RS-232 transceivers is the capability for switching between two standard configurations:

DTE port and DCE port. The most common example is a dumb terminal or personal computer (DTE port)

connected to an external modem (DCE port). For this case, the connecting cable provides straight-through,

1-to-1 connections. Similarly, the serial cable for a printer is designed to plug into a DTE port at the

computer end.

But, problems arise if you must connect two computers together. Both are DTEs, so the standard DTE-to-

DCE cable won't work. The usual solution is a special LapLink™ cable, or a "null modem" that converts

one of the DTE ports to a DCE. A null modem is nothing more than two back-to-back connectors with

various wires transposed. The most common type of null modem is fully implemented by a single chip

(MAX214) whose internal circuitry (under the control of a single logic-level input) performs all the

necessary wiring transpositions.

Maxim Achieves Industry's Highest ESD Protection: ±15kV

Protection level complies with human body model and IEC 801-2 air-gap discharge method

ESD (electrostatic discharge) threatens an electronic system every time someone replaces a cable or

touches an I/O port. The discharges accompanying these routine events can render an I/O port useless by

destroying one or more interface ICs connected to the port. These failures can be expensive in terms of both

warranty repairs and perceived quality.

www.maxim-ic.com/an654

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