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Interface Repeater Powered by V28 or RS232C Modem EIA Drivers

IP.com Disclosure Number: IPCOM000042579D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 65K

Publishing Venue

IBM

Related People

Vachee, P: AUTHOR

Abstract

In an interface repeater which allows the V24 interface data/control signals to be serialized and transmitted on one or two twisted pairs, a circuit is provided to remotely power the repeater connected to the modem. Two drivers (DRV) in the modem interface are used to power the repeater. The Data Set Ready and Received Data drivers are used for generating the +V and -V voltages in the repeater provided that a diode arrangement and a capacitor limit the ripple on the -V voltage. If the repeater logic is built with MOS technology, the main power consumption comes from the four EIA drivers. To be in compliance with the V28 or RS232C standard, the EIA driver must accept a load neither less than 3000 ohms nor more than 7000 ohms and the effective shunt capacitance should not exceed 2500 pF.

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Interface Repeater Powered by V28 or RS232C Modem EIA Drivers

In an interface repeater which allows the V24 interface data/control signals to be serialized and transmitted on one or two twisted pairs, a circuit is provided to remotely power the repeater connected to the modem. Two drivers (DRV) in the modem interface are used to power the repeater. The Data Set Ready and Received Data drivers are used for generating the +V and -V voltages in the repeater provided that a diode arrangement and a capacitor limit the ripple on the -V voltage. If the repeater logic is built with MOS technology, the main power consumption comes from the four EIA drivers. To be in compliance with the V28 or RS232C standard, the EIA driver must accept a load neither less than 3000 ohms nor more than 7000 ohms and the effective shunt capacitance should not exceed 2500 pF. The rise and fall time of the voltage change must be lower than 30 volts per microsecond to reduce crosstalk. The driver must withstand occasional voltage surges on its output of up to Å 15 volts. To avoid excessive module dissipation, it is accepted that only one driver at a time is allowed to be connected to externally applied voltage within the +15-volts to -15-volt range. The driver must be equipped with a current limiter to meet the module dissipation requirement of 300 or 350 mW. Normally an EIA driver can provide an output current up to 12 mA without excessive power dissipation. In the proposed application, the re...