Line drive circuit for fire alarm system and corresponding fire alarm system

摘要

The present invention proposes a drive circuit and drive method for a fire alarm system. The drive circuit comprises: a current generation circuit, capable of selectively supplying either a first current I N1 or a second current I ALARM to the line, wherein the first current I N1 is used as a line monitoring current in a normal operating state, and the second current I ALARM is greater than the first current I N1 ; and a detection circuit, for controlling the current generation circuit to supply the second current I ALARM to the line when detecting that a line voltage V Line on the line is lower than a threshold V th , wherein the threshold V th is lower than a normal line voltage but higher than a maximum alarm voltage indicated on the line when the fire detector gives an alarm.