ICS1660

The ICS1660 "ICLID" circuit is a monolithic CMOS VLSI device that decodes and detects the Frequency Shift Keying (FSK) signals used in caller identification telephone service.The ICS1660, when used in conjunction with some external components, amplifies, filters and demodulates the FSK data transmitted from the central office to the telephone subscriber.

The ICS1660 detects the first power ring signal and demodulates the 1200 baud FSK data transmitted during the silent interval between the first and second power ring. The FSK data is transmitted from the central office switch to the subscriber line as part of the CLASS service of Calling Number Delivery (CND). This data is then demodulated, amplified and filtered by the ICS1660 and digitally transmitted to the host controller/processor.

The ICS1660 is designed to be powered by any off-the-shelf 9.0 volt battery. The on-chip 5.0 voltage regulator powers the host microprocessor and any external circuitry supported by the ICS1660. This portion of the circuit can be overridden by connecting the VIN pin (18) to the VDD pin (1) for a common power supply. A low battery detection circuit is also provided on-chip and signals the microprocessor on the FSK/BAT pin (17) when the PWR pin (16) input is pulled low.