MOTOROLA TCA3385-FP

The TCA3385 is primarily designed to convert the ringing signal supplied by a central office or PABX into a DC voltage suitable for powering other components in an electronic telephone. When the telephone is on-hook, it powers the telephone's advanced features such as MPU control, generation and amplification of loudspeaker ringing melodies, and display of short messages. The circuit combines a highly efficient DC/DC converter with a level sensing device that functions as a programmable ring detector and MPU indicator, thereby initiating telephone operation. Overvoltage protection is also implemented using "crowbar" technology.

• High-efficiency step-down DC/DC converter with linear input impedance
• Power sourced from rectified AC ringing signal or DC voltage
• Drive output for external PNP transistor
• System supply voltage determined by external transistor, inductor, and diode
• Two operating modes: fixed internal or programmable ring detection threshold (7 to 35V)
• Programmable input impedance: 3K to 15KΩ
• Ring detection output for microprocessor
• Lightning and AC line protection

• Telephone
• Answering machine
• Home appliances