Methods and apparatus for controlling a notification appliance circuit

• US 20100066557A1
• Filed: 02/06/2009
• Published: 03/18/2010
• Est. Priority Date: 02/08/2008
• Status: Active Grant

• Current Assignee: Siemens Industry Incorporated (Siemens AG)
• Original Assignee: Siemens Industry Incorporated (Siemens AG)
• Inventors: Henson, James C., Lontka, Karen D.
• Granted Patent: US 8,373,571 B2
• Time in Patent Office: Days
• US Class Current: 340/693.100
• CPC Class Codes: H02H 9/001 limiting speed of change of electric quantities, e.g. soft switching on or off progressive control of electronic switches for eliminating interferences H03K17/16

Abstract

An arrangement for use in a safety notification system includes an alarm signal power source, a first semiconductor device, a current sensing unit, and a controller unit. The alarm signal power source is configured to generate bias power for activating a notification appliance circuit of a notification system. The first semiconductor device has a load path coupled between the alarm signal power source and the notification appliance circuit. The current sensing unit is operably coupled to generate a sensing signal that is dependent on the current in the load path. The controller circuit is operably connected to receive the current sensing signal and to control the first semiconductor device responsive to a current sensing signal that exceeds an in-rush current threshold.

Claims

1. An arrangement for use in a safety notification system, comprising:

a) an alarm signal power source, the alarm signal power source configured to generate bias power for activating a notification appliance circuit of a notification system;

b) at least a first semiconductor device having a load path coupled between the alarm signal power source and the notification appliance circuit;

c) a current sensing unit operably coupled to generate a sensing signal that is dependent on the current in the load path;

d) a controller circuit operably connected to receive the current sensing signal and to control the first semiconductor device responsive to a current sensing signal that exceeds an in-rush current threshold.

2. The arrangement of claim 1, wherein the first semiconductor device is a MOSFET.

3. The arrangement of claim 2, wherein the current sensing unit includes a sense resistor and wherein the current sensing signal comprises a voltage level of a terminal of the sense resistor.

4. The arrangement of claim 1, wherein the controller circuit further comprises a first input for receiving an alarm control signal, and wherein the controller further controls the first semiconductor device responsive to the alarm control signal.

5. The arrangement of claim 2, wherein the controller circuit operably controls the MOSFET to limit the current through the load by changing a gate voltage of the MOSFET.

6. The arrangement of claim 1, further comprising a current measurement circuit operably coupled to the current sense unit, the current measurement circuit configured to generate a signal indicative of whether the current through the load path exceeds a steady state current threshold.

7. The arrangement of claim 1, further comprising a processing circuit configured to cause the controller circuit to control the first semiconductor device such that the first semiconductor device does not conduct current through the load path responsive to the signal indicating that the current through load path exceeds a steady state threshold.

8. The arrangement of claim 7, wherein the processing circuit is configured to generate a shutdown signal responsive to the signal indicating that the current through load path exceeds a steady state threshold, and wherein the processing circuit is configured provide the shutdown signal to the first input.

9. An arrangement for use in a safety notification system, comprising:

a) an alarm signal power source, the alarm signal power source configured to generate bias power for activating a notification appliance circuit of a notification system;

b) at least a first semiconductor device having a load path coupled between the alarm signal power source and the notification appliance circuit;

c) a current sensing unit operably coupled to generate a sensing signal that is dependent on the current in the load path;

d) a hot swap controller operably connected to receive the current sensing signal and to control the first semiconductor device responsive to a current sensing signal, said control including limiting the current through the load path when said current exceeds an in-rush current threshold.

10. The arrangement of claim 9, wherein the first semiconductor device is a MOSFET.

11. The arrangement of claim 10, wherein the current sensing unit includes a sense resistor and wherein the current sensing signal comprises a voltage level of a terminal of the sense resistor.

12. The arrangement of claim 9, wherein the hot swap controller further comprises a first input for receiving an alarm control signal, and wherein the hot swap controller further controls the first semiconductor device responsive to the alarm control signal.

13. The arrangement of claim 10, wherein the hot swap controller operably controls the MOSFET to limit the current through the load by changing a gate voltage of the MOSFET.

14. The arrangement of claim 9, further comprising a current measurement circuit operably coupled to the current sense unit, the current measurement circuit configured to generate a signal indicative of whether the current through the load path exceeds a steady state current threshold.

15. The arrangement of claim 9, further comprising a processing circuit configured to cause the hot swap controller to control the first semiconductor device such that the first semiconductor device does not conduct current through the load path responsive to the signal indicating that the current through load path exceeds a steady state threshold.

16. The arrangement of claim 15, wherein the processing circuit is configured to generate a shutdown signal responsive to the signal indicating that the current through load path exceeds a steady state threshold, and wherein the processing circuit is configured provide the shutdown signal to the first input.