Witura WT-9001 IP65 Spécifications télécharger pdf (Page 44)

Figure 3.7 Voltage Regulator Circuit

3.1.2.4 Max 232 Serial Level Converter

Almost all digital devices which used require either Transistor-Transistor Logic

(TTL) logic levels. Therefore the first step to connecting a device to the RS-232 port is

to transform the RS-232 levels back into 0 and 5 Volts. When these voltages have

already covered, this is done by RS-232 Level Converters. Two common RS-232 Level

Converters are the 1488 RS-232 Driver and the 1489 RS-232 Receiver. Each package

contains 4 inverters of the one type, either Drivers or Receivers. The driver requires two

supply rails, +7.5 to +15v and -7.5 to -15v. As user could imagine this may pose a

problem in many instances where only a single supply of +5V is present. However the

advantages of these I.C's are they are cheap.

Another device is the MAX-232. It includes a Charge Pump, which generates

+10V and -10V from a single 5v supply. This I.C. also includes two receivers and two

transmitters in the same package. This is handy in many cases when user only want to

use the Transmit and Receive data Lines. Don't need to use two chips, one for the

receive line and one for transmit. However all this convenience comes at a price, but

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Witura WT-9001 IP65 Spécifications Page 44