73M1903C

73M1903C Modem Analog Front End Simplifying System IntegrationTM DS_1903C_033 DESCRIPTION The 73M1903C Analog Front End (AFE) IC includes fully differential hybrid driver outputs, which connect to the telephone line interface through a transformerbased DAA. The receive pins are also fully differential for maximum flexibility and performance. This arrangement allows for the design of a high performance hybrid circuit to improve signal to noise performance under low receive level conditions, and compatibility with any standard transformer intended for PSTN communications applications. The device incorporates a programmable sample rate circuit to support soft modem and DSP based implementations of all speeds up to V.92 (56 kbps). The sampling rates supported are from 7.2 kHz to 16.0 kHz by programming the pre-scaler NCO and the PLL NCO. The 73M1903C device incorporates a digital host interface that is compatible with the serial ports found on most commercially available DSPs and processors and exchanges both payload and control information with the host. This interface can be configured as a single master/slave mode or as a daisy chain mode that allows the user to connect up to eight 73M1903C devices to a single host for multi Analog Front End applications, such as, central server modems. Costs saving features of the device include an input reference frequency circuit, which accepts a range of crystals from 4.9-27 MHz. It also accepts external reference clock values between 1 MH...