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SSI73K212LBell 212A/1 03Single-Chip ModemAPPLICATlONS INFORMATIONGENERAL CONSIDERATIONSFigures 1 and 2 show basic circuit di~grams forK -Series modem integrated circuits. K-Series productsare designed to be used in conjunction with a controlprocessor, a UART or RS-232 serial data interface,and a DAA phone line interface to function as a typicalintelligent modem. The K-Series ICs interface directlywith Intel 8048 and 80C51 microprocessors for controland status monitoring purposes.Two typical DAA arrangementsare shown: one for a split ±5 or±12 voltdesign and one for a single 5 volt design. Thesediagrams are for reference only and do not representproduction-ready modem designs.K-Series devices are available with two control interfaceversions: one tor a parallel multiplexed address/data interface, and one for a serial interface. Theparallel version is intended for use with 8039/48 or8031/51 microcontrollers from Intel or many othermanufacturers. The serial interface 22-pin version can• be used with other microcontroJlers or in applicationswhere only a limited number of port lines are availableor the application does not lend itself to a multiplexedaddress/data interface. The parallel versions may alsobe used in the serial mode, as explained in the datasheet pin description.In most applications the controJlerwiJl monitor the serialdata for commands from the DTE and the receiveddata for break signals from the far end modem. In thisway, commands to the modem are sent overthe sameline as the transmitted data. In other applications theRS-232 interface handshake lines are used for modemcontrol.RS232LEVELCONVERTERSCA I-f>.+-=C:----!CB I-