Description The CPC5712 is a special purpose Voltage Monitor with Detectors integrated circuit that is used in various high-voltage telephony applications such as VoIP gateways and IP-PBXs. The device monitors the TIP/RING potential through a high-impedance divider （resistor isolation） to derive two programmable signal level detects， polarity information， and a scaled representation of the phone line voltages. In use， the resistor divider and the high input impedance of the CPC5712 make the circuit practically undetectable on the line. The two voltage-level detects are programmed with external resistors， which gives the designer complete freedom with respect to line voltage detection levels. The level settings also have programmable hysteresis to prevent false triggering conditions. Detection of these levels allows the user to determine the condition of the line. This device can also be used in non-telephony applications such as instrumentation and industrial controls， especially when a low-level differential level needs to be detected in the presence of a large common-mode voltage.