Latch circuit

• US 3,988,643 A
• Filed: 10/25/1974
• Issued: 10/26/1976
• Est. Priority Date: 10/25/1974
• Status: Expired due to Term

• Current Assignee: Monroe Systems For Business, Inc. (Carolina Wholesale Office Machine Company, Inc.)
• Original Assignee: Litton Marine Systems Inc.
• Inventors: Morris, David
• Primary Examiner(s): Miller, J D
• Assistant Examiner(s): Salce, Patrick R.
• Application Number:
  US05/518,103
• Time in Patent Office: 732 Days
• Field of Search: 317/33 VR, 317/31, 317/33 SC, 323/22 T, 323/17, 323/9, 323/DIG. 1, 307/297, 307/288, 307/272, 307/289, 321/2
• US Class Current: 361/18
• CPC Class Codes: H02M 3/1563 without using an external clock H02M3/158 takes precedence

Abstract

A Schmidt trigger voltage regulator having a latching circuit at its input to disable the regulator during an overload condition and automatically resets the latching circuit when the overload condition is removed thereby allowing the regulator to function in its normal voltage regulating mode.

Claims

1. An electrical power supply comprising:

a switching voltage regulator circuit including a Schmitt trigger circuit means; and

latch means, coupled to said Schmitt trigger circuit means, for turning the switching voltage regulator off when the load current exceeds a predetermined value and which automatically resets itself when the load current goes below said predetermined value, including a pair of opposite conductivity transistors, each having a base, emitter, and collector, and a diode coupled from the collector of one of said transistors to the base of the said other transistor.

2. An electric power supply according to claim 1 wherein said latch comprises:

a sensing resistor,

a pair of opposite conductivity transistors, each having a base, emitter, and collector, and

biasing means coupled to said pair or transistors, including a first and second resistor means, the first resistor means coupled to one end of said sensing resistor and the second resistor means coupled to the other end of said sensing resistor.

3. An electric power supply according to claim 1 wherein said latch circuit comprises:

a pair of opposite conductivity transistors, each having a base, emitter, and collector, and

biasing means, coupled to said pair of transistors, including a third resistor means coupled between the base and emitter of one of said transistors.

4. An electric power supply according to claim 1 wherein said latch means comprises:

a sensing resistor,

a pair of opposite conductivity transistors, each having a base, emitter, and collector,

a diode coupled from the collector of one of said transistors to the base of said other transistor, and

biasing means coupled to said pair of transistors, including a first and second resistor means each coupled to one end of said sensing resistor, and a third resistor means coupled between the base and emitter of one of said transistors.