Patent ID: 9641023
Date: 2017-05-02
CPC Classifications: G05F,H02J,H04M,Y02B,Y04S

Claim:
1. A standby power supply circuit for a 2-wire bus intercom system, wherein said standby power supply circuit is separated into two power supply modules, the standby power supply circuit comprising: a first power supply module that is a power supply to a standby circuit and a second power supply module that is a power supply to an operation circuit; wherein said power supply to the operation circuit is switched off by a constant current switch when a device load is at a standby status; wherein said power supply to the standby circuit comprises a constant current circuit with an alternating current impedance; wherein said power supply to the standby circuit further comprises the constant current circuit connected between an input terminal and a standby regulator circuit; wherein said constant current circuit further comprises a main constant current circuit and an auxiliary constant current circuit, wherein said main constant current circuit stabilizes current through a main constant current path of said main constant current circuit; wherein said auxiliary constant current circuit offers a bias current for the main constant current circuit under a bias voltage while maintaining an AC impedance.