SHORT CIRCUIT PROTECTION DEVICE FOR MULTIPLE POWER SUPPLIES

• US 3,665,253 A
• Filed: 12/02/1970
• Issued: 05/23/1972
• Est. Priority Date: 12/02/1970
• Status: Expired due to Term

• Current Assignee: Richard D. Stefani
• Original Assignee: Richard D. Stefani
• Inventors: Stefani, Richard D.
• Primary Examiner(s): Trammell, James D.
• Application Number:
  US05/094,376
• Time in Patent Office: 538 Days
• Field of Search: 317/33VR,22,36TD,38,50,31 323/22T
• US Class Current: 361/74
• CPC Class Codes: G05F 1/573 with overcurrent detector

Abstract

A short circuit protection device includes a surge protection circuit having first and second input connections coupled to a voltage source and a control circuit, respectively, and an output connection coupled to a plurality of voltage regulator circuits. The output voltages of the regulator circuit are sensed through a gate circuit by the control circuit. In the event one of the regulator output voltages goes to zero, the control circuit directs a control signal to the surge protection circuit which then disconnects the voltage source from the plurality of regulator circuits.

Claims

1. A device for protecting a power source comprising:

a load having an output voltage associated therewith;

a surge protection circuit having an input connection coupled to said power source, an output connection coupled to said load, and a control terminal and being operative to couple energy from said power source to said load; and

voltage sensing means having an input connection coUpled to said load and an output connection coupled to the control terminal of said surge protection circuit and being operative to direct a control signal to said control terminal when the output voltage at said load falls below a predetermined value;

said surge protection circuit being operative in response to the control signal at its control terminal from said voltage sensing means to decouple said load from said power source and being operative in response to a surge condition at its input connection to decouple said load from said power source;

said voltage sensing means including means having an input connection coupled to said load and an output connection and being operative to generate an output signal at its output connection when an output voltage less than a predetermined level occurs at the input connection, and first transistor circuit means having an input connection connected to the output connection of said last-mentioned means and an output connection coupled to the control terminal of said surge protection circuit and being operative in response to the output signal from said last-mentioned means to generate said control signal;

means coupled between said surge protection circuit and the input connection of said first transistor circuit means, for rendering said first transistor circuit means nonresponsive to a signal from said surge protection circuit during said surge condition; and

second transistor circuit means having an input connection and an output connection connected to the output connection and input connection, respectively, of said first transistor circuit means and being operative to render said first transistor circuit means nonresponsive to signals at its input connection after said control signal is generated by said first transistor.

2. A device for protection a power source according to claim 1 wherein:

said load includes a plurality of regulated voltage supplies each having an input connection coupled to said surge protection circuit and an output connection coupled to said voltage sensing means and being operative to generate a regulated output voltage; and

said means in said voltage sensing means includes gating means having an input connection coupled to each of said regulated supplies and an output connection connected to the input connection of the first transistor circuit means and being operative to generate an output signal at its output connection if any one of the output voltages is less than a predetermined level.

3. A device for protecting a power source according to claim 2 wherein said surge protection circuit includes:

third transistor circuit means, coupled between said power source and said plurality of regulated voltage supplies, having a control element and being operative in response to a control signal at its control element to decouple said power source from said plurality of regulated voltage supplies;

fourth transistor circuit means having an input connection coupled to said power source and to said control terminal and an output connection and being operative in response to either a surge at said power source or a signal from said first transistor circuit means to change from a first condition to a second condition at its output connection; and

fifth transistor circuit means having an input connection coupled to the output connection of said fourth transistor and an output connection coupled to the control element of said third transistor circuit means and being operative in response to the second condition of said fourth transistor circuit means to generate said control signal at the control element of said third transistor circuit means.

4. A device for protecting a power source according to claim 3 further including a sixth transistor circuit means having an input connection coupled to the output connection of said fourth transistor circuit means and an output connection coupled to the input connection of said first transistor means and being operative in response to the second condition at the output connection of said fourth transistor circuit means caused by the surge at said power source to inhibit the generation of a control signal at said control terminal.