Circuit arrangement and method for protecting a control element against overcurrent

• US 6,424,512 B1
• Filed: 03/07/2000
• Issued: 07/23/2002
• Est. Priority Date: 09/08/1997
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Schmacht, Thomas
• Primary Examiner(s): Han, Jessica
• Assistant Examiner(s): Tibbits, Pia
• Application Number:
  US09/508,161
• Time in Patent Office: 868 Days
• Field of Search: 361/18, 361/56, 361/58, 361/93, 361/111, 361/118, 361/119, 323/265, 323/266, 323/270, 323/271, 323/273, 323/274, 323/276, 323/277-282, 363/59, 363/60
• US Class Current: 361/93.1
• CPC Class Codes: G05F 1/569 for protection

Abstract

A circuit arrangement and method for overload protection for a control element is provided, wherein the voltage across a control path of the control element is monitored and utilized as a criterion for shutting off the control element. The actual shutting off of the control element is effected through the aid of a protection circuit that inhibits the control element above a critical current level.

Claims

1. A circuit arrangement for overload protection of a first control element comprising:

a voltage source;

a load;

a first control element having a first control path selectively connecting the voltage source to the load, at least one control input for selectively controlling the first control path, and at least one output terminal connected to the load and at least one input terminal connected to the voltage source, wherein the at least one output terminal connected to the load and the at least one input terminal connected to the voltage source respectively comprise a first control path output and a first control path input;

a protective circuit arranged electrically parallel to the first control path of the first control element, wherein the protective circuit is configured to monitor voltage across the first control path of the first control element and, drive the control input of the first control element when a short in the load occurs such that the load is separated from the voltage source.

2. The circuit arrangement according to claim 1 further comprising:

a first input resistor arranged between the first control path input and the at least one output terminal of the protective circuit connected to the voltage source.

3. The circuit arrangement according to claim 1 further comprising:

a resistor arranged between the control input of the first control element and the at least one terminal of the protective circuit connected to the voltage source.

4. The circuit arrangement according to claim 2, wherein the protective circuit comprises a second control element having a second control path.

5. The circuit arrangement according to claim 4 further comprising:

a second input resistor having a first terminal connected to an input of the second control path of the second control element and a second terminal connected via the first input resistor to the first control path input, and a third resistor arranged at an output of the second control path of the second control element and connected via a first protective resistor to the control input of the first control element.

6. The circuit arrangement according to claim 4, wherein the first and second control elements are MOS transistors.

7. The circuit arrangement according to claim 5 further comprising:

a control input of the second control element connected via a second protective resistor to the first control path output.

8. The circuit arrangement according to claim 5 further comprising:

a drive unit having an output that is connected via the first protective resistor to the control input of the first control element and an input of the drive unit connected to a measurement sensor connected to the load.

9. The circuit arrangement according to claim 7 further comprising:

a capacitor is arranged between the input of the second control path and the control input of the second control element.

10. A method for overload protection of a first control element having a control path that connects a load to a voltage source, the method comprising the steps of:

monitoring a voltage across the control path of the first control element; and

driving a control input of the first control element when a short circuit in the load occurs, wherein the control path of the first control element is interrupted and the load is separated from the voltage source.