73M1903

Simplifying System IntegrationTM DESCRIPTION The Teridian 73M1903 Analog Front End (AFE) IC includes fully differential hybrid driver outputs, which connect to the telephone line interface through a transformer-based 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 14.4 kHz by programming pre-scaler NCO and PLL NCO. The 73M1903 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. Cost-saving features of the device include an input reference frequency circuit, which accepts a range of crystals from 9-27 MHz. It also accepts external reference clock values between 9-40 MHz generated by the host processor. In most applications, this eliminates the need for a dedicated crystal oscillator and reduces the bill of material (BOM). The 73M1903 also supports two analog loop back and one digital loop back test modes. (HYBRID) VBG TXAP TXAN Transmit D...