Methods and apparatus for auxiliary trickle power supply

• US 5,490,053 A
• Filed: 09/30/1993
• Issued: 02/06/1996
• Est. Priority Date: 09/30/1993
• Status: Expired due to Term

• Current Assignee: Apple Computer Incorporated (Apple Inc.)
• Original Assignee: Apple Computer Incorporated (Apple Inc.)
• Inventors: Sontag, Harold L. III, Tkacenko, Nikola
• Primary Examiner(s): Sterrett, Jeffrey L.
• Application Number:
  US08/129,621
• Time in Patent Office: 859 Days
• Field of Search: 363/15, 363/39, 363/44, 363/45, 363/46, 363/123
• US Class Current: 363/15
• CPC Class Codes: H02M 3/28 using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac

Abstract

Circuit arrangements and methods are disclosed for providing trickle voltages and currents when a main power supply is unavailable or, alternatively, for providing auxiliary power. In one embodiment, a trickle power supply consists of a bilaterally conducting semiconductor diode device such as a SIDAC receiving an unregulated DC input voltage through a resistor. The SIDAC is contemplated to have a specified breakover voltage V_bo and current carrying capability chosen according to designer preference. A first capacitor is coupled between the SIDAC and a primary side of a step-down pulse transformer providing a specified reduction in voltage from a secondary side relative to the voltage applied to the primary side. The resistor, the first capacitor, and the SIDAC together form a modified RC resonant circuit oscillation characteristic. When the unregulated DC input voltage is applied, the first capacitor will charge up to the breakover voltage V_bo of the SIDAC, whereafter the SIDAC becomes strongly conducting and charge is rapidly discharged to ground from the first capacitor through the SIDAC. When the stored charge has been depleted, the SIDAC becomes nonconducting, and charge is thereafter again accumulated in the first capacitor. The alternate charging and discharging of the first capacitor according to the V_bo of the SIDAC produces an oscillating pulse waveform. The pulse waveform is subsequently reduced in magnitude by the pulse transformer, and thereafter routed through voltage regulating means to adjust the reduced voltage and current of the oscillating pulse waveform to an output trickle voltage and current of specified magnitude.

Claims

1. A trickle power supply for generating trickle voltages and currents, said trickle power supply comprising:

charge storage means coupled to an unregulated direct current (DC) source for receiving and storing electric charge;

bidirectionally conducting semiconductor diode means coupled to the charge storage means for enabling said charge storage means to alternately charge and discharge, thereby generating a periodic oscillating waveform having a plurality of alternating charging and discharging profiles;

voltage reducing means coupled to said charge storage means and said bidirectionally conducting semiconductor diode means for converting said periodic oscillating waveform into a reduced voltage periodic oscillating waveform, and

voltage regulation means coupled to said voltage reducing means for accumulating and converting said reduced periodic oscillating waveform into regulated voltage and current outputs comprising said trickle voltages and currents.

2. The trickle power supply as set forth in claim 1, wherein said charge storage means comprises a resistor for providing an electrical resistance and a first capacitor for providing a first electrical capacitance, said resistor and said first capacitor coupled together and having a charging profile substantially similar to an RC circuit charging profile when said unregulated DC source is applied to the trickle power supply.

3. The trickle power supply as set forth in claim 1, wherein said bidirectionally conducting semiconductor diode means comprises a SIDAC having a breakover voltage V_bo, said SIDAC comprising a high impedance high voltage nonconducting first state when said unregulated DC source is below V_bo, said SIDAC further comprising a low impedance low voltage conducting second state when said unregulated DC source is above V_bo.

4. The trickle power supply as set forth in claim 1, wherein said voltage reducing means comprises a miniature pulse step-down transformer having a high voltage primary side and a low voltage secondary side, said pulse transformer producing said reduced voltage periodic oscillating waveform at its secondary side when said periodic oscillating waveform is applied to its primary side.

5. The trickle power supply according to claim 1 further comprising means for generating continuous DC trickle voltages and currents from an alternating current (AC) source, said means for generating continuous DC trickle voltages and currents comprising AC rectifying and filtering means coupled between an AC line input and said charge storage means, said AC rectifying and filtering means comprising:

a first diode coupled to receive and rectify an AC line input signal, and

a first capacitor coupled to the first diode for providing a filtered, unregulated direct current (DC) voltage and current, said first capacitor further coupled to said charge storage means of said trickle power supply.

6. The trickle power supply as set forth in claim 1, wherein said voltage regulation means comprises a first diode coupled to said voltage reducing means for substantially removing the charging and discharging profiles from said reduced voltage periodic oscillating waveform, a capacitor coupled to said first diode for accumulating said reduced voltage periodic oscillating waveform, and a Zener diode coupled to said capacitor for adjusting said reduced voltage periodic oscillating waveform such that the regulated voltage and current of the trickle supply correspond to a chosen design point.

7. The trickle power supply as set forth in claim 1 further comprising a charge recovery means for recovering a portion of charge discharged through said bidirectionally conducting semiconductor diode means, said charge recovery means comprising a rectifying means coupled to said bidirectionally conducting semiconductor diode means for redirecting the portion of charge to said charge storage means according to an amount of energy inductively stored in said voltage reducing means.

8. The trickle power supply as set forth in claim 7, wherein said rectifying means comprises a "catch" diode coupled across said bidirectionally conducting semiconductor diode means.

9. A trickle power supply for generating trickle voltages and currents from an unregulated direct current (DC) source, said trickle power supply comprising:

a resistor coupled to said unregulated DC power source;

a first capacitor coupled to said resistor for storing charge delivered by said unregulated DC power source;

a SIDAC semiconductor device coupled to the resistor and the capacitor for enabling said capacitor to alternately charge and discharge, thereby generating a periodic oscillating waveform having a plurality of alternating charging and discharging profiles;

said SIDAC having a breakover voltage V_bo, said SIDAC comprising a high impedance high voltage nonconducting first state when said unregulated DC source is below V_bo, said SIDAC further comprising a low impedance low voltage conducting second state when said unregulated DC source is above V_bo ;

voltage reducing means coupled to said first capacitor and said SIDAC semiconductor device for converting said periodic oscillating waveform into a reduced voltage periodic oscillating waveform, and

voltage regulation means coupled to said voltage reducing means for accumulating and converting said modified periodic oscillating waveform into a regulated voltage and current outputs, said voltage regulation means thereby producing said trickle voltages and currents.

10. The trickle power supply as set forth in claim 9 further comprising a charge recovery means for recovering a portion of charge discharged through said SIDAC, said charge recovery means comprising a "catch" diode coupled to said SIDAC for redirecting said portion of charge to the first capacitor according to an amount of energy inductively stored in said voltage reducing means.

11. The trickle power supply as set forth in claim 9, wherein said voltage reducing means comprises a miniature pulse step-down transformer having a high voltage primary side and a low voltage secondary side, said pulse transformer producing said reduced voltage periodic oscillating waveform at its secondary side when said periodic oscillating waveform is applied to its primary side.

12. The trickle power supply as set forth in claim 9, wherein said voltage regulation means comprises a first diode coupled to said voltage reducing means for substantially removing the charging and discharging profiles from said reduced voltage periodic oscillating waveform, a second capacitor coupled to said first diode for accumulating said reduced voltage periodic oscillating waveform, and a Zener diode coupled to the second capacitor for adjusting said reduced voltage periodic oscillating waveform such that the regulated voltage and current of the trickle supply correspond to a chosen design point.

13. In a trickle power supply, a method for generating trickle voltages and currents comprising the steps of:

receiving and storing charge from an unregulated direct current (DC) source in a charge storage means;

generating a periodic oscillating waveform having a plurality of alternating charging and discharging profiles using a bidirectionally conducting semiconductor diode means coupled to said charge storage means, said bidirectionally conducting semiconductor diode means enabling said charge storage means to alternately charge and discharge;

converting said periodic oscillating waveform into a reduced voltage periodic oscillating waveform using a voltage reducing means coupled to said charge storage means and said bidirectionally conducting semiconductor diode means, and

accumulating and converting said reduced voltage periodic oscillating waveform into regulated voltage and current outputs using a voltage regulation means coupled to said voltage reducing means, said regulated voltage and current outputs comprising said trickle voltages and currents.

14. The method according to claim 13 further comprising the step of recovering a portion of charge discharged through said bidirectionally conducting semiconductor diode means according to an amount of energy inductively stored in said pulse transformer means.

15. The method according to claim 14, wherein the step of recovering said portion of charge comprises providing a charge recovery means including a second rectifying means coupled to said bidirectionally conducting semiconductor diode means.

16. The method according to claim 15, wherein said second rectifying means comprises a "catch" diode coupled across said bidirectionally conducting semiconductor diode means.

17. The method according to claim 13, wherein the step of generating said periodic oscillating waveform comprises the step of coupling a bidirectionally conducting semiconductor diode means to said unregulated DC source and said charge storage means to alternately charge and discharge said charge storage means, thereby generating said periodic oscillating waveform.

18. The method according to claim 17, wherein said bidirectionally conducting semiconductor diode means comprises a SIDAC having a breakover voltage V_bo, wherein said SIDAC comprises a high impedance high voltage nonconducting first state when said unregulated DC source is below V_bo, said SIDAC further comprising a low impedance low voltage conducting second state when said unregulated DC source is above V_bo.

19. The method according to claim 13, wherein said voltage reducing means comprises a miniature pulse step-down transformer having a high voltage primary side and a low voltage secondary side, said pulse step-down transformer producing said modified periodic oscillating waveform at its secondary side when said periodic oscillating waveform is applied to its primary side.

20. The method according to claim 13, wherein the step of storing charge comprises providing a resistor means having an electrical resistance and a first capacitor means having a first electrical capacitance for generating an RC oscillating waveform when said unregulated DC source is applied to the trickle power supply.

21. The method according to claim 13, wherein said step of accumulating and converting said reduced voltage periodic oscillating waveform using said voltage regulation means comprises:

coupling a first diode to said voltage reducing means for substantially removing the charging and discharging profiles from said reduced voltage periodic oscillating waveform,

coupling a capacitor to said first diode for accumulating said reduced voltage periodic oscillating waveform, and

coupling a Zener diode to said capacitor for adjusting said reduced voltage periodic oscillating waveform such that the regulated voltage and current of the trickle supply correspond to a chosen design point.

22. The method according to claim 13 further comprising the step of generating continuous DC trickle voltages and currents from an alternating current (AC) source by providing rectifying and filtering means coupled between an AC line input and said charge storage means, said AC rectifying and filtering means comprising:

a first diode coupled to receive and rectify an AC line input signal, and

a first capacitor coupled to the first diode for providing a filtered, unregulated direct current (DC) voltage and current, said first capacitor further coupled to said charge storage means of said trickle power supply.