DC-to-DC Voltage converter

• US 4,451,743 A
• Filed: 12/09/1981
• Issued: 05/29/1984
• Est. Priority Date: 12/29/1980
• Status: Expired due to Term

• Current Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Original Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Inventors: Suzuki, Fuminori, Ichikawa, Singo
• Primary Examiner(s): Goldberg, E. A.
• Assistant Examiner(s): Jennings, Derek
• Application Number:
  US06/328,990
• Time in Patent Office: 902 Days
• Field of Search: 307/110, 363/59, 363/60, 363/61, 363/62, 320/1, 323/370
• US Class Current: 307/110
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps

Abstract

A DC-to-DC voltage converter is disclosed for converting the voltage from a battery to provide a power supply voltage whose value can be equal to the battery voltage multiplied by or divided by a non-integral factor, e.g. 2/3. The converter operates on the principle of capacitor charge switching, and high conversion efficiency is achieved in operation at very low levels of supply current, such as are utilized in an electronic timepiece.

Claims

1. The combination of a battery voltage detection circuit and a DC-to-DC converter circuit for converting the voltage of a battery for thereby producing a power supply voltage to be applied to a load, said battery voltage detection circuit being operable for producing detection signals in accordance with the value of said battery voltage, said DC-to-DC converter circuit comprising:

a main capacitor;

a plurality of auxiliary capacitors;

a source of switching signals provided by said load; and

switch means responsive to said switching signals for controlling the interconnection conditions between said main capacitor, said auxiliary capacitors, said load and said battery such as to repetitively and alternately establish a first operating condition in which said auxiliary capacitors are connected in parallel with one another and are connected in series with said main capacitor and a second operating condition in which said auxiliary capacitors are connected in series with one another and are collectively connected in parallel with said main capacitor, said switch means being coupled to said auxiliary capacitors and responsive to said detection signals for selectively varying the number of said auxiliary capacitors effectively functioning in said DC-to-DC converter circuit, for thereby varying the value of the ratio between said supply voltage and said battery voltage in a manner to compensate for changes in said battery voltage.

2. A DC-to-DC converter circuit for converting the voltage of a battery for thereby providing a first and a second power supply voltage to be applied to first and second input terminals of a load respectively, the value of said first power supply voltage being equal to said battery voltage multiplied by a factor of 3/2 the value of said second power supply voltage being equal to one half of said battery voltage, comprising:

a source of switching signals provided by said load;

a power supply capacitor fixedly connected across said first input terminals of said load;

a main capacitor;

a pair of auxiliary capacitors;

a first group of electronic switches coupled to control the interconnection conditions between said main capacitor, said auxiliary capacitors, said battery and said first input terminals of said load, and responsive to said switching signals for establishing a first operating condition in which said auxiliary capacitors are connected in parallel with one another and are collectively connected in series with said main capacitor across said first input terminals of said load while being disconnected from said battery, and a second operating condition in which said auxiliary capacitors are connected in series with one another and are collectively connected in parallel with said main capacitor across said battery while being disconnected from said first input terminals of said load, said first group of electronic switches acting to repetitively and alternately establish said first and second operating states for thereby developing said first power supply voltage across said first input terminals of said load;

first and second voltage dropping capacitors, said first voltage dropping capacitor being fixedly connected across said second input terminals of said load; and

a second group of electronic switches coupled to control the interconnection conditions between said first and second voltage dropping capacitors, said battery and said second input terminals of said load in response to said switching signals for thereby repetitively and alternately establishing a first operating condition in which said first and second voltage dropping capacitors are connected in series across said battery and a second operating condition in which said first and second voltage dropping capacitors are connected in parallel across said second input terminals of said load, whereby said second power supply voltage is developed across said second input terminals of said load.

3. A DC-to-DC converter circuit according to claim 2, in which said load comprises an electronic circuit and in which said source of switching signals comprises a switching signal generating circuit forming a part of said electronic circuit.

4. A DC-to-DC converter circuit according to claim 3, in which said battery is a lithium battery.

5. A DC-to-DC converter circuit according to claim 4, in which said electronic circuit comprises a matrix drive circuit for a liquid crystal display device.

6. A DC-to-DC converter circuit for converting the voltage of a battery for thereby producing a power supply voltage to be applied to a load, comprising:

a main capacitor, said main capacitor being fixedly connected in parallel with said load;

a set of n auxiliary capacitors each having a value of capacitance equal to that of said main capacitor wherein "n" is an integer;

a source of switching signals provided by said load; and

a plurality of electronic switch means responsive to said switching signals for controlling the interconnection conditions between said main capacitor, said auxiliary capacitors, said load and said battery such as to repetitively and alternately establish a first operating condition in which said n auxiliary capacitors are connected in parallel with one another and are connected in series with said main capacitor and a second operating condition in which said n auxiliary capacitors are connected in series with one another and are collectively connected in parallel with said main capacitor, to thereby establish a value of said power supply voltage which is substantially equal to said battery voltage multiplied by a factor which is a function of n, during said first operating condition said auxiliary capacitors being connected in parallel with one another and being connected as a group in series with said main capacitor across said battery to be charged therefrom, and during said second operating condition, said auxiliary capacitors being disconnected from said battery and being connected in series with one another and connected as a series-connected group in parallel with said main capacitor, to thereby establish a value of said supply voltage which is substantially equal to said battery voltage multiplied by a factor n/(n-1).

7. A DC-to-DC converter circuit according to claim 6, and further comprising a power supply capacitor fixedly connected across said load, and in which said auxiliary capacitors are arranged as a set of m groups, and in which during said first operating condition the auxiliary capacitors of the respective groups are connected in series with one another and said m groups are disconnected from said load and connected in parallel with one another and with said main capacitor across said battery to be charged thereby, and in which during said second operating condition the capacitors of each of said groups of auxiliary capacitors are respectively connected in parallel with one another and said groups of auxiliary capacitors connected in series with one another and said main capacitor across said load, with said main capacitor and auxiliary capacitors being disconnected from said battery.

8. A DC-to-DC converter circuit according to claim 6, and further comprising electronic switch means coupled to said auxiliary capacitors for selectively varying the number of auxiliary capacitors effectively functioning in said DC-to-DC converter circuit, for thereby varying the value of said supply voltage.

9. A DC-to-DC converter circuit for converting the voltage of a battery for thereby producing a power supply voltage to be applied to a load, comprising:

a power supply capacitor fixedly connected in parallel with said load;

a main capacitor;

a set of n auxiliary capacitors each having a value of capacitance equal to that of said main capacitor wherein "n" is an integer;

a source of switching signals provide by said load; and

a plurality of electronic switch means responsive to said switching signals for controlling the interconnection conditions between said main capacitor, said auxiliary capacitor, said load and said battery such as to repetitively and alternately establish a first operating condition in which said n auxiliary capacitors are connected in parallel with one another and are connected in series with said main capacitor and a second operating condition in which said n auxiliary capacitors are connected in series with one another and are collectively connected in parallel with said main capacitor, to thereby establish a value of said power supply voltage which is substantially equal to said battery voltage multiplied by a factor which is a function of n, during said first operating condition said auxiliary capacitors being connected in parallel with one another and being connected as a group in series with said main capacitor, with said main capacitor and auxiliary capacitors being disconnected from said battery; and

further during said second operating condition said auxiliary capacitors being connected in series with one another and being connected as a group in parallel with said main capacitor and in parallel with said battery to be charged therefrom, with said main capacitor and auxiliary capacitors being disconnected from said load to thereby establish a value of said supply voltage which is substantially equal to said battery voltage multiplied by a factor of (1+1/n).

10. A DC-to-DC converter circuit for converting the voltage of a battery for thereby producing a power supply voltage to be applied to a load, comprising:

a power supply capacitor fixedly connected across said load;

a main capacitor;

a set of n auxiliary capacitors each having a value of capacitance equal to that of said main capacitor and in which said auxiliary capacitors are arranged as a set of m groups wherein "n" and "m" are integers;

a source of switching signals provided by said load; and

a plurality of electronic switch means responsive to said switching signals for controlling the interconnection conditions between said main capacitor, said auxiliary capacitors, said load and said battery such as to repetitively and alternately establish a first operating condition in which said n auxiliary capacitors are connected in parallel with one another and are connected in series with said main capacitor and a second operating condition in which said n auxiliary capacitors are connected in series with one another and are collectively connected in parallel with said main capacitor, to thereby establish a value of said power supply voltage which is substantially equal to said battery voltage multiplied by a factor which is a function of n, during said first operating condition the auxiliary capacitors of the respective groups being connected in series with one another and said m groups being disconnected from said load and connected in parallel with one another and with said main capacitor across said battery to be charged thereby, and during said second operating condition the capacitors of each of said groups of auxiliary capacitors being respectively connected in parallel with one another and said groups of auxiliary capacitors being connected in series with one another and said main capacitor across said load, with said main capacitor and auxiliary capacitors being disconnected from said battery, each of said groups of auxiliary capacitors containing an indentical number s of capacitors wherein "S" is an integer, whereby the value of said supply voltage is established which is substantially equal to said battery voltage multiplied by a factor (1+s/m).