UMC 2400

The UMC 2400 has the following features including Audio interface for phone line monitoring;Programmable audio output level control;Both DSP and AFE in 28 pin DIP or PLCC packages;Needs only one clock source;On chip DTMF/GUARD tone generator;On chip hybrid circuit;Easily controlled by microcontroller.

The UMC  2400 bps modem chip set is a 2-wire full  duplex,synchronous  and asynchronous CCITT V.22 bis modem data pump.It is designed to operate over the public switched telephone network(PSTN),as well as leased lines.This chip set is used in  conjunction with an  external controller such as Intel 8051,to implement a 2400 bps full duplex modem.The external  controller performs all modem controls and some modem functions.  The UMC modem chip set contains two chips--UM 92240 DSP chip and  UM92241 AFE.The UM92240 DSP chip performs most of the receiving functions.The other chip UM92241 AFE performs most of the transmission  functions and some of the receiving functions.This  modem chip set operates at  2400 bps QAM and 1200 bps PSK as well as 0 to 300 baud FSK modes,compatible with Bell 212A and 103 as well as  CCITT V .22 bis,V .22 and  V .21  standards.When used with external controller,the UMC 2400 bps modem chip set performs industry standard "AT" command set,and becomes an intelligent modem.  When used with Bus Interface chip UM92242,an internal modem will be easily implemented.The  UM92242  has a built-in UART and  some circuits that are usually found in interfacing with IBM compatible PC bus slot.This minimizes the component count in implementing the internal modem.

After power up,some initialization process should be provided for this data pump.Following power up,the data in the registers of AFE chip UM92241 are undefined and the output pins may deliver  unwanted signals.Controlto registers  of UM92241  must be properly  programmed  to obtain the wanted operation.The DSP chip UM92240 will be initialized and execute program from the starting address 0 after an active high pulse on RESET pin.