WAKE-UP CIRCUIT FOR A SECURITY DEVICE

摘要

An exemplary security device includes a reader configured to read information stored on a credential device. The reader enters a sleep mode when not reading a credential device. A wake-up module includes an inductively coupled resonant circuit. The wake-up module is configured to detect a credential device near the reader if the credential device has a resonant frequency corresponding to a frequency of an electromagnetic field of the inductively coupled resonant circuit that is controlled by a stable oscillator. The wake-up module is configured to provide an indication to wake-up the reader from the sleep mode responsive to detecting a change in power of the electromagnetic field caused by the credential device.