Direct current power converters employing digital techniques used in electronic timekeeping apparatus

• US 3,955,353 A
• Filed: 07/10/1974
• Issued: 05/11/1976
• Est. Priority Date: 07/10/1974
• Status: Expired due to Term

• Current Assignee: Optel Corporation
• Original Assignee: Optel Corporation
• Inventors: Astle, Brian
• Primary Examiner(s): Shoop, William M.
• Application Number:
  US05/487,319
• Time in Patent Office: 671 Days
• Field of Search: 58/23 BA, 58/50 R, 321/2, 321/15, 307/109, 307/110, 320/1
• US Class Current: 368/157
• CPC Class Codes: G04G 19/04 Capacitive voltage division or multiplication
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps

Abstract

A converter utilizes a low voltage battery to develop a higher potential by the use of capacitors which are charged sequentially according to digital waveforms provided by counting type circuits and gates. The charge transfer circuits afford a low impedance charging path and a high impedance discharge path via a series of transmission gate controlled capacitors.

The apparatus permits the conversion of low battery voltages while being completely compatible with ultra-miniature electronic systems.

Claims

1. In an electronic watch assembly of the type employing an accurate source of oscillations for providing a timekeeping signal, said watch including a low voltage battery for energizing circuitry included in said watch, the combination therewith of apparatus for converting said low voltage battery potential to a higher voltage level, comprising:

a. means coupled to said accurate source of oscillations for providing at least first and second waveforms synchronized one to the other, said waveforms characterized in that said first one is at a positive level when said second one is negative and vice versa, said waveforms having no condition where both can be positive or both can be negative, as the waveforms do not overlap,

b. a first capacitor having a first and second terminal,

c. a second capacitor having a first and second terminal with said second terminal coupled to a point of reference potential,

d. a plurality of transmission gates each having an input and output terminal and capable of operating in a low impedance state upon application of a predetermined potential level to a control electrode associated with each of said gates,

e. means coupling one of said terminals of said first capacitor to an output terminal of a first one of said transmission gates and said other terminal to an output of another of said transmission gates, the input of said first transmission gate being coupled to a terminal of said low voltage battery and the input of said another gate being coupled to a point of reference potential, and

f. means coupling said first terminal of said second capacitor to an output of still another transmission gate with said input of said gate coupled to a terminal of said first capacitor, said control electrodes of said gates being responsive to a selected one of said first and second waveforms to energize said gates in a predetermined sequence whereby said low battery voltage charges said capacitors via said gates in a manner to provide a different potential then said battery potential across said second capacitor, said second capacitor only being coupled to said battery during said second waveform and only when said first capacitor is not so coupled, whereby said first and second capacitors are never in parallel, and

g. means for transferring said charge across said first and second capacitors to a third output capacitor.

2. The converting apparatus according to claim 1, wherein said transmission gates comprise at least one field effect transistor having a source output terminal, a drain input terminal, and a gate control electrode.

3. The converting apparatus according to claim 2, wherein said field effect device is bilateral.

4. The converting apparatus according to claim 1, wherein said means coupled to said accurate source of oscillations comprise a plurality of cascaded multivibrators for dividing said accurate source by a given integer, and gating means coupled to said multivibrators for providing said first and second waveforms at respective ouputs of gating means.

5. The apparatus according to claim 4, wherein said multivibrators are flip-flops employing MOS devices.

6. The apparatus according to claim 1, wherein said potential across said second capacitor is greater than said battery potential.

7. The apparatus according to claim 1, wherein said potential across said second capacitor is a rational fraction of said battery potential.

8. The apparatus according to claim 1, wherein said potential across said second capacitor is an arbitrary fraction of said battery potential.

9. The apparatus according to claim 1, wherein said potential across said second capacitor is relatively equal to said battery potential multiplied by the integer 2n, where n is greater than 1.

10. The apparatus according to claim 1, wherein said first terminal of said second capacitor is coupled to said means coupled to said accurate source for energizing the same with said potential level across said capacitor.

11. Converting apparatus for providing a predetermined potential level at an output, which level is different from a source of operating potential, comprising:

a. means for providing at least first and second waveforms synchronized one to the other, said waveforms characterized in that said first one is at a positive level when said second one is negative and vice versa, said waveforms having no condition where both can be positive or both can be negative, as the waveforms do not overlap,

b. at least first and second capacitors, each having a first and second terminal, one of said terminals of one of said capacitors being coupled to a point of reference potential,

c. a plurality of transmission gates, each having an input, output, and a control electrode and adapted to provide a low impedance path between said input and output electrodes upon application of said high potential to said control electrode,

d. means connecting said other terminals of said capacitors in circuit with said transmission gates, with said control electrodes responsive to either said first or second waveforms to sequentially charge said capacitors in accordance with said waveforms via said controlled low impedance paths of said transmission gates to cause one of said capacitors to develop said different potential level thereacross, wherein, due to said waveforms, one of said capacitors is only coupled to said battery when the other of said capacitors is not and said first and second capacitors are never in parallel, and

e. means for transferring said charge across said first and second capictors to a third output capacitor.

12. The converting apparatus according to claim 11, wherein said means for providing at least said first and second waveforms comprises a crystal oscillator capable of providing a relatively stable output signal of a given frequency, and counting means coupled to said oscillator for providing a series of digital waveshapes, decoding means responsive to said waveshapes for providing at an output said first and second waveforms.

13. The converting apparatus according to claim 11, wherein said transmission gates are parallel p channel, n channel MOS devices.

14. The converting apparatus according to claim 11, wherein said level different from said operating potential is 2n times the same, where n is an integer greater than 1.

15. The converting apparatus according to claim 12, wherein said crystal oscillator is that included as a time-keeping source in an electronic watch apparatus.