VL7C412

The VL7C412 is a complete, 5 V single supply, 300/1200 bit-per-second modem enhanced with a pin to allow external control of the receiver's gain.All of the signal processing functions needed for a full duplex, 300/1200 bit-per-second 212A (V.21 or V.22) modem,including both FSK and PSK modulators and demodulators and the high-band and low-band filters, are integrated on a single chip.It is built using a three-micron CMOS double-polysilicon process that allows analog and digital functions to be combined on the same chip.This design includes capabilities for progress monitoring and for generating DTMF as well as V.21 or V.22 guard tones.The two-to-four wire hybrid is also included, simplifying the interface to a DAA. The VL7C412 also includes analog loopback and remote digital loopback functions for self-testing.

The VL7C412 has the following features include:(1)FSK and PSK modulators and demodulators, high-band and low-band filters with compromise amplitude and group delay equalizers;(2)single 5 V power supply with power down by pin or code;(3)pin programmable receiver gain;(4)built-in call progress mode and tone generators for DTMF V.21 and V.22 guard tones;(5)bell 212A and CCITT V.21 and V.22 compatible; V.22 notch fillers included;(6)serial control interface;(7)programmable audio output port;(8)analog,digital, and remote digital loopback capabilities;(9)24-pin DIP and 28-pin plastic leaded chip carrier available.

The absolute maximum ratings of the VL7C412 are:(1)storage temperature range:-65 to +140°C;(2)ambient temperature under bias:-10 to +80°C;(3)maximum supply voltage:+7V;(4)maximum power disspation:500mW.Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device.These are shess ratings only and functional operation of the device at these or any other conditions beyond those indicated in the operational secObns of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.Another version of the controller, the VL7C214, is intended for RS-232 applications.It contains the same processor, memory, and UART as the VL7C213 and has the same interface to the modem chip. The difference is that the UART is turned around so that serial data from the RS-232 port is converted to parallel data handled by the internal processor.Pins are provided for connecting the familiar switches and indicator lamps found on most stand-alone modems, aRhough the switches and lamps are not needed for operation.All of the switch settings can be done through software.