Dual Mode 300- and 1200-Baud V.21 and V.23 Single-Chip Modem

MC145745 removed from active portfolio. Possible replacement part: none.

The MC145745 is a selectable modem chip compatible with ITU V.21 (300 baud full duplex asynchronous) and V.23 mode 2 (1200 baud half duplex asynchronous). The built-in differential line driver has the capability of driving 0 dBm into a 600 ohm load with a 5 V single power supply. This device also includes a DTMF generator, DTMF receiver, call-progress tone detector, answer tone generator, and a receive timing control circuit.

Besides having a clock generator with a crystal oscillator connected to it, the device has a divider circuit to which input of a double frequency clock is possible from external sources, such as from a microcontroller unit (MCU). The serial control port (SCP) permits the MCU to access internal registers for exercising the built-in features.

A low consumption device, the MC145745 integrates various functions in a small package. This modem IC is best suited for telemeter and other applications of this type.