Switching regulator power supply

• US 4,001,663 A
• Filed: 09/03/1974
• Issued: 01/04/1977
• Est. Priority Date: 09/03/1974
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Bray, William Edward
• Primary Examiner(s): Goldberg, Gerald
• Application Number:
  US05/502,703
• Time in Patent Office: 854 Days
• Field of Search: 323/17, 323/21, 323/22 T, 323/DIG. 1, 323/34, 323/35, 323/36, 323/38, 321/2, 321/18, 307/237, 307/238, 307/239, 307/296, 307/297, 340/189 R
• US Class Current: 363/37
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop

Abstract

A switching regulator power supply operates at a high frequency with a low loss, light weight ferrite core transformer. The transformer primary is selectively connected across a DC source of rectified AC power for a predetermined time to provide energy storage followed by a predetermined time period of disconnect to provide energy transfer by way of transformer flyback. The energy storage and energy transfer cycles are initiated by a novel, self-starting timing circuit. The power parameters in at least one of a plurality of secondary windings are sensed and compared with a reference standard. Any error, in the form of a pulse-width-modulated pulse is coupled back to a primary control for adjustment of the energy storage time period. The coupling is done through a sealed opto-electronic coupler, this providing a DC coupling.

Claims

1. A switching regulator power supply for connection to a DC source of rectified AC power with a regulation cycle having an energy storage cycle and an energy transfer cycle, comprising:

a. timing means, for continuously providing a predetermined time period for the energy storage cycle and a predetermined time period for the energy transfer cycle;

b. power switching means, connected to one side of the DC source and connected to the timing means to close and provide power during the energy storage cycle and to open during the energy transfer cycle;

c. a transformer having a primary winding with one end connected to the other side of the DC source and the other end connected to the power switching means to permit current to flow in one direction during the energy storage cycle and in the other direction during the energy transfer cycle and at least one secondary winding biased to permit current flow only during the energy transfer cycle;

d. indicating means operatively connected to the secondary winding to provide electrical signals indicative of secondary electrical power parameters the electrical signals including an end regulation cycle signal; and

e. first direct current coupling means, connected to the indicating means and to the timing means to couple the RCE signal to the timing means, the timing means being responsive to the RCE signal for adjusting the time of the energy storage cycle to a finite time more than zero.

2. The power supply of claim 1 wherein the first direct current coupling means are an opto-coupler, having a light emitting device connected to the output of the indicating means and a light responsive device connected to the timing means.

3. The power supply of claim 2 wherein the timing means further comprise a one-shot multivibrator circuit, a triggering circuit for providing a repetitive triggering signal to the one-shot multivibrator at predetermined time intervals and an output circuit for providing an output timing signal.

4. The power supply of claim 3 wherein the transformer has a plurality of secondary windings, each secondary winding having a unidirectional current conducting device oriented to prevent current flow during the energy storage cycle and to permit current flow during the energy transfer cycle.

5. The power supply of claim 1 wherein the timing means further comprise a one-shot multivibrator circuit, a triggering circuit for providing a repetitive triggering signal to the one-shot multivibrator at predetermined time intervals and an output circuit for providing an output timing signal.

6. The power supply of claim 1 wherein the transformer has a plurality of secondary windings, each secondary winding having a unidirectional current conducting device oriented to prevent current flow during the energy storage cycle and to permit current flow during the energy transfer cycle.

7. The power supply of claim 6 wherein one of the plurality of secondary windings is connected to the indicating means.

8. A switching regulator power supply for connection to a DC source of rectified AC power with a regulation cycle having an energy storage cycle and an energy transfer cycle, comprising:

a. timing means, for providing a predetermined time period for the energy storage cycle and a predetermined time period for the energy transfer cycle;

b. i. a power drive transistor and a power switching transistor connectedd together in a Darlington configuration, the power switching transistor being connected to the transformer primary winding for closing and providing power during the energy storage cycle and for opening during the energy transfer cycle; and

ii. a power clock transistor for providing the base drive to the power driver transistor and connected to provide a voltage input to the timing means;

c. a transformer having a primary winding with one end connected to the other side of the DC source and the other end connected to the power switching transistor to permit current to flow in one direction during the energy storage cycle and in the other direction during the energy transfer cycle and at least one secondary winding biased to permit current flow only during the energy transfer cycle;

d. indicating means, operatively connected to the secondary winding to provide electrical signals indicative of secondary electrical power parameters, the electrical signals including an end regulation cycle (RCE) signal; and

e. first direct current coupling means, connected to the indicating means and to the timing means to couple the RCE signal to the timing means, the timing means being responsive to the RCE signal for adjusting the time of the energy storage cycle.

9. A switching regulator power supply for connection to a DC source of rectified AC power with a regulation cycle having an energy storage cycle and an energy transfer cycle, comprising:

a. timing means including a one-shot multivibrator circuit, a triggering circuit for providing a repetitive triggering signal to the one-shot multivibrator at predetermined time intervals and an output circuit for providing an output timing signal for providing a predetermined time period for the energy storage cycle and a predetermined time period for the energy transfer cycle;

b. i. a power driver transistor and a power switching transistor connected together in a Darlington configuration, the power switching transistor being connected to the transformer primary winding for closing and providing power during the energy storage cycle and for opening during the energy transfer cycle; and

ii. a power clock transistor for providing the base drive to the power driver transistor and connected to provide a voltage input to the timing means;

c. a transformer having a primary winding with one end connected to the other side of the DC source and the other end connected to the power switching transistor to permit current to flow in one direction during the energy storage cycle and in the other direction during the energy transfer cycle, and a plurality of secondary windings, each secondary winding having a unidirectional current conducting device oriented to prevent current flow during the energy storage cycle and to permit current flow during the energy transfer cycle;

d. indicating means, operatively connected to the secondary winding to provide electrical signals indicative of secondary electrical power parameters, the electrical signals including an end regulation cycle (RCE) signal; and

e. an opto-coupler, having a light emitting device connected to the output of the indicating means and a light responsive device connected to the timing means to couple the RCE signal to the timing means, the timing means being responsive to the RCE signal for adjusting the time of the energy storage cycle.

10. The power supply of claim 9 further comprising:

f. a self-start circuit connected across a selected one of the secondary windings and operatively connected to said indicating means to prevent an RCE signal until the voltage across the selected winding rises to a predetermined value.

11. A switching regulator power supply for connection to a DC source of rectified AC power with a regulation cycle having an energy storage cycle and an energy transfer cycle, comprising:

a. timing means, for providing a predetermined time period for the energy storage cycle and a predetermined time period for the energy transfer cycle;

b. power switching means, connected to one side of the DC source and connected to the timing means to close and provide power during the energy storage cycle and to open during the energy transfer cycle;

c. a transformer having a primary winding with one end connected to the other side of the DC source and the other end connected to the power switching means to permit current to flow in one direction during the energy storage cycle and in the other direction during the energy transfer cycle and at least one secondary winding biased to permit current flow only during the energy transfer cycle;

d. indicating means, operatively connected to the secondary winding to provide electrical signals indicative of secondary electrical power parameters, the electrical signals including an end regulation cycle (RCE) signal;

e. first direct current coupling means, connected to the indicating means and to the timing means to couple the RCE signal to the timing means, the timing means being responsive to the RCE signal for adjusting the time of the energy storage cycle; and

f. second direct current coupling means, connected to and responsive to the timing means and connected to the secondary circuit for providing to the indicating means regulaton cycle start (RCS) signal.

12. The power supply of claim 11 wherein the timing means further comprise a one-shot multivibrator circuit, a triggering circuit for providing a repetitive triggering signal to the one-shot multivibrator at predetermined time intervals and an output circuit for providing an output timing signal.

13. The power supply of claim 11 wherein the indicating means comprise:

d. i. a first Schmidt trigger circut having input means responsive to the RCS signal and connected to receive the voltage from the secondary winding;

ii. a reference voltage generating circuit; and

iii. a comparison circuit connected to the first Schmidt trigger circuit and to the reference voltage generating circuit for providing the RCE signal.

14. The power supply of claim 11, further comprising:

g. a protection circuit, connected to the indicating means for sensing excessive voltage and excessive current and for providing a signal indicative of excessive voltage or excessive current;

h. a primary latch circuit, connected to the output of said timing means to inhibit output from the timing circuit when the primary latch circuit is activated; and

i. third direct current coupling means connected from the protection circuit to the primary latch circuit to activate the primary latch circuit in the presence of a signal indicative of excessive voltage or excessive current.

15. The power supply of claim 14 wherein the indicating means comprise:

d. i. a first Schmidt trigger circuit having input means responsive to the RCS signal and connected to receive the voltage from the secondary winding;

ii. a reference voltage generating circuit; and

iii. a comparison circuit connected to the first Schmidt trigger circuit and to the reference voltage generating circuit for providing the RCE signal.

16. The power supply of claim 14 wherein the third direct coupling means are an opto-coupler having a light emitting device connected to the protection circuit and a light responsive device connected to the primary latch circuit.

17. The power supply of claim 16 wherein the timing means further comprise a one-shot multivibrator circuit, a triggering circuit for providing a repetitive triggering signal to the one-shot multivibrator at predetermined time intervals and an output circuit for providing an output timing signal.

18. The power supply of claim 14 wherein the timing means further comprise a one-shot multivibrator circuit, a triggering circuit for providing a repetitive triggering signal to the one-shot multivibrator at predetermined time intervals and an output circuit for providing an output timing signal.

19. The power supply of claim 18 wherein the first direct current coupling means are an opto coupler, having a light emitting device connected to the output of the indicating means and a light responsive device connected to the timing means.

20. The power supply of claim 19 wherein the second direct current coupling means are an opto coupler having a light emitting device connected to the clock circuit and a light responsive device connected to the input of the indicating means.

21. The power supply of claim 20 wherein the third direct coupling means are an opto coupler having a light emitting device connected to the protection circuit and a light responsive device connected to the primary latch circuit.

22. The power supply of claim 21 wherein the power switching means comprise:

b. i. a power driver transistor and a power switching transistor connected together in a Darlington configuration, the power switching transistor being connected to the transformer primary winding; and

ii. a power clock transistor for providing the base drive to the power driver transistor and connected to provide a voltage input to the one-shot multivibrator circuit and the triggering circuit.

23. The power supply of claim 22 wherein the transformer has a plurality of secondary windings, each secondary winding having a unidirectional current conducting device oriented to prevent current flow during the energy storage cycle and to permit current flow during the energy transfer cycle.

24. The power supply of claim 23 wherein one of the plurality of secondary windings is connected to the indicating means.

25. The power supply of claim 24 wherein the indicating means comprise:

d. i. a first Schmidt trigger circuit having input means responsive to the RCS signal and connected to receive the voltage from the secondary winding;

ii. a reference voltage generating circuit; and

iii. a comparison circuit connected to the first Schmidt trigger circuit and to the reference voltage generating circuit for providing the RCE signal.

26. The power supply of claim 25 further comprising:

k. a self-start circuit connected across a selected one of the secondary windings and operatively connected to the comparison circuit to prevent an RCE signal until the voltage across the selected winding rises to a predetermined value.

27. The power supply of claim 11 wherein the second direct current coupling means are an opto-coupler having a light emitting device connected to the clock circuit and a light responsive device connected to the input of the indicating means.

28. The power supply of claim 27 wherein the timing means further comprise a one-shot multivibrator circuit, a triggering circuit for providing a repetitive triggering signal to the one-shot multivibrator at predetermined time intervals and an output circuit for providing an output timing signal.

29. The power supply of claim 28 wherein the transformer has a plurality of secondary windings, each secondary winding having a unidirectional current conducting device oriented to prevent current flow during the energy storage cycle and to permit current flow during the energy transfer cycle.

30. The power supply of claim 29 wherein one of the plurality of secondary windings is connected to the indicating means.

31. The power supply of claim 30 wherein the power switching means comprise:

b. i. a power driver transistor and a power switching transistor connected together in a Darlington configuration, the power switching transistor being connected to the transformer primary winding; and

ii. a power clock transistor for providing the base drive to the power driver transistor and connected to provide a voltage input to the one-shot multivibrator circuit and the triggering circuit.

32. The power supply of claim 31 wherein the first direct current coupling means are an opto coupler, having a light emitting device connected to the output of the indicating means and a light responsive device connected to the timing means.

33. The power supply of claim 32 wherein the indicating means comprise:

d. i. a first Schmidt trigger circuit having input means responsive to the RCS signal and connected to receive the voltage from the secondary winding;

ii. a reference voltage generating circuit; and

iii. a comparison circuit connected to the first Schmidt trigger circuit and to the reference voltage generating circuit for providing the RCE signal.

34. The power supply of claim 33 further comprising:

g. a self-start circuit connected across a selected one of the secondary windings and operatively connected to the comparison circuit to prevent an RCE signal until the voltage across the selected winding rises to a predetermined value.

35. A switching regulator power supply for connection to a DC source of rectified AC power, with a regulation cycle having an energy storage cycle and an energy transfer cycle, comprising:

a. timing means, for providing a predetermined time period for the energy storage cycle and a predetermined time period for the energy transfer cycle;

b. power switching means, connected to one side of the DC source and connected to the timing means to close and provide power during the energy storage cycle and to open during the energy transfer cycle;

c. a transformer, having a primary winding with one end connected to the other side of the DC source and the other end connected to the power switching means to permit current to flow in one direction during the energy storage cycle and in the other direction during the energy transfer cycle and at least one secondary winding biased to permit current flow only during the energy transfer cycle;

d. indicating means, operatively connected to the secondary winding to provide electrical signals indicative of secondary electrical power parameters; and

e. direct current coupling means, connected to and responsive to said timing means and connected to the secondary circuit for providing to said indicating means a regulation cycle start (RCS) signal.

36. The power supply of claim 35 wherein the direct current coupling means are an opto-coupler having a light emitting device connected to the clock circuit and a light responsive device connected to the input of the indicating means.

37. A switching regulator power supply for connection to a DC source of rectified AC power with a regulation cycle having an energy storage cycle and an energy transfer cycle, comprising:

a. timing means, for continuously providing a predetermined time period for the energy storage cycle and a predetermined time period for the energy transfer cycle;

b. power switching means, connected to one side of the DC source and connected to the timing means to close and provide power during the energy storage cycle and to open during the energy transfer cycle;

c. a transformer, having a primary winding with one end connected to the other side of the DC source and the other end connected to the power switching means to permit current to flow in one direction during the energy storage cycle and in the other direction during the energy transfer cycle and at least one secondary winding biased to permit current flow only during the energy transfer cycle;

d. indicating means, operatively connected to the secondary winding to provide electrical signals indicative of secondary electrical power parameters, the electrical signal including an end regulation cycle (RCE) signal;

e. a protection circuit, connected to the indicating means for sensing excessive voltage and excessive current and for providing a signal indicative of excessive voltage or excessive current;

f. a primary latch circuit, connected to the output of the timing circuit to inhibit output from the timing circuit when the primary latch circuit is activated; and

g. direct current coupling means connected from the protection circuit to the primary latch circuit to activate the primary latch circuit in the presence of the signal indicative of excessive voltage or excessive current.

38. The power supply of claim 37 wherein the direct coupling means are an opto-coupler having a light emitting device connected to the protection circuit and a light responsive device connected to the primary latch circuit.

39. A method of providing a regulated voltage from a DC source, comprising the steps of:

a. connecting the primary windings of a transformer across the DC source for a predetermined time, always providing an energy storage cycle of a finite time more than zero;

b. biasing the secondary windings of the transformer to prevent current flow during the energy storage cycle;

c. removing the primary windings of the transformer from the DC source for a predetermined time;

d. providing a current path for opposite current flow when the primary windings are removed from the DC source, enabling an energy transfer cycle;

e. permitting current flow in the secondary windings of the transformer during the energy transfer cycle;

f. monitoring the secondary windings induced voltage and providing a signal (RCE) if the voltage is higher than a predetermined value; and

g. DC coupling the RCE signal through an opto-coupler to end the energy storage cycle.