SELF-OSCILLATING SWITCHING REGULATOR WITH FREQUENCY REGULATION THROUGH HYSTERETIC CONTROL OF THE SWITCHING CONTROL TRIGGER CIRCUIT

• US 3,660,753 A
• Filed: 12/21/1970
• Issued: 05/02/1972
• Est. Priority Date: 12/21/1970
• Status: Expired due to Term

• Current Assignee: Frank Fuller Judd, Helmut Wilhart, Jan Mark Lieberman
• Original Assignee: Frank Fuller Judd, Helmut Wilhart, Jan Mark Lieberman
• Inventors: Judd, Frank Fuller, Lieberman, Jan Mark, Wilhart, Helmut
• Primary Examiner(s): Pellinen, A. D.
• Application Number:
  US05/100,148
• Time in Patent Office: 498 Days
• Field of Search: 321/2 323/4,17,22T,38,DIG.1
• US Class Current: 323/283
• CPC Class Codes: H02M 3/1563 without using an external clock H02M3/158 takes precedence
• CPC Class Codes: H03F 2200/351 Pulse width modulation being used in an amplifying circuit

Abstract

A self-oscillating switching mode regulator is frequency regulated by directly controlling the hysteresis of the switching control circuit in the voltage control feedback loop. The switching control circuit includes a hysteretic bistable trigger circuit whose hysteresis width defined by its upper and lower triggering levels may be widened or narrowed about some mean signal level in response to a frequency error signal.

Claims

1. A self-oscillating switching regulator to derive a regulated voltage from an unregulated voltage source comprising an input and an output, a switching device coupling said input and output, a voltage regulation feedback loop to control said switching device, said voltage regulation loop including a bistable trigger circuit with hysteretic switching characteristics to sustain self-oscillations which drive said switching device, a frequency control reference voltage source, means to generate a frequency responsive voltage responsive to the switching frequency of said switching device, means to compare said responsive voltage and said reference voltage and derive an error voltage therefrom, and said bistable trigger circuit including a hysteresis control circuit to adjust its hysteretic trigger signal threshold response in response to said error voltage whereby the switching frequency of said switching device is maintained at a constant value.

2. A self-oscillating switching regulator in accord with claim 1 wherein said bistable trigger circuit includes a bistable switching circuit with two input leads whereby the respective magnitudes of the signal inputs to each lead determine the hysteresis of the overall trigger circuit, and said hysteresis control circuit comprises means to control the signal level applied to the said two input leads.

3. A self-oscillating switching regulator in accord with claim 2 wherein said means to generate a frequency responsive voltage includes a frequency-to-voltage converter and said hysteresis control circuit comprises two differentially coupled amplifying devices, one of said amplifying devices being responsive to the frequency-to-voltage converter and the other amplifying device being responsive to a reference voltage.

4. A self-oscillating switching regulator in accord with claim 2 wherein said hysteresis control circuit comprises a bridge circuit with four impedance branches, and a controlled resistance coupling two branch nodes of the bridge and responsive to said means to generate a frequency responsive voltage.

5. A self-oscillating switching regulator to derive a regulated output voltage from an unregulated voltage source comprising a switching device including a control electrode to control switching therein, a voltage regulating feedback loop coupled to said control electrode, a frequency regulating feedback loop including a hysteretic trigger circuit coupled to said control electrode and including a frequency-to-voltage converter responsive to the switching frequency of the switching regulator, a reference voltage source, voltage comparator means to compare the voltage of said converter and said reference voltage, and a hysteresis control circuit to electronically adjust the hysteresis of said trigger circuit in response to the output of said voltage comparator.

6. A self-oscillating switching Regulator in accord with claim 5 wherein said hysteretic trigger circuit comprises a hysteresis control circuit, a bistable switching circuit, said hysteresis control circuit comprising means to derive two fractional level signals of different magnitudes from said feedback signals in said voltage regulating feedback loop in response to said voltage comparator, and said bistable switching circuit comprises cross-coupled logic NOR gates with a NOR logic gate as a first input to one of said cross-coupled gates and a second direct input to the other cross-coupled gate whereby the first and second fractional level signals are applied to the first and second inputs, respectively.