Patent ID: 7400227
Filing Date: 2008-07-15
Classification: G08B,H03K

Abstract:
1. A power supply for driving alarm notification appliances, comprising: a driver circuit configured to apply power to an electrical load; a first current limited drive enable circuit configured to activate the driver circuit and to establish a first upper drive limit for the driver circuit; a second current limited drive enable circuit configured to activate the driver circuit and to establish a second upper drive limit for the driver circuit; a drive limit selection criterion; a drive level sensor configured to provide to the drive control function an indication of a drive level in the driver circuit; a drive control function comprising an analysis sequence wherein the drive level indication from the drive level sensor is compared to a time versus drive level profile, and a shutdown rule wherein at least one shutdown threshold is defined for a drive level indication with respect to the time versus drive level profile, wherein a drive limit imposed on the driver circuit is determined at least in part by the selection criterion.