EDE1400 Просмотр технического описания (PDF) - Unspecified
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EDE1400 Datasheet PDF : 7 Pages
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The following schematic illustrates the connection of a PC to a parallel printer via the EDE1400.
Notice that a MAX232 Voltage level converter IC is used to provide the interface between the
EDE1400 and the PC.
Figure Two: Connection to PC
EDE1400 SPECIAL POWER CONSIDERATIONS
If your application allows the printer to remain powered while the host system is powered down, the
EDE1400 will remain powered from leakage current coming from the printer's data and control lines
(which it holds high continually). This may cause garbage characters to be printed when the host is
again powered up due to noise on the data line. If this is a problem in your application, it can be
remedied by supplying power to the EDE1400 through a diode such as the 1N4004. In parallel with
this should be a 220 Ohm, 1/8 watt resistor. The diode will allow power to flow to the EDE1400
from the host when it is powered without allowing power to return to the host system from the
printer when the printer is on and the host system is powered down. The resistor is necessary to
ensure that the EDE1400 will not stay powered up and operative when only the printer is powered.
Figure Three: Alternate Power Supply Circuit
Note: You might also choose to place a 4.7K pull-up resistor on the serial data line to ensure that
no data is printed on the printer due to noise on the serial line.
Copyright © 1997 E-Lab Digital Engineering, Inc. All Rights Reserved. Page 6
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