JJ-20.11-Compatible Interface for the DS2155 and DS21455 SCTs

This application note describes how the Dallas Semiconductor DS2155 or DS21455 single-chip transceiver (SCT) can be used to create an interface that is compatible with the Japanese JJ-20.11 standard. Both the DS2155 and DS21455 have a digital multiplexer and I/O interface that provide access to the clock and bipolar data signals between the framer and LIU sections. Using a FPGA or CPLD, the data steam can be modified to support the JJ-20.11 standard. Because the LIU already has the ability to code and decode the Coded Mark Inversion (CMI) signal used in JJ-20.11, only a slight modification is needed to increase the gain of the receive signal.