Method and related device for charging at the same voltage two or more capacitors connected in series

• US 7,893,662 B2
• Filed: 07/07/2008
• Issued: 02/22/2011
• Est. Priority Date: 07/09/2007
• Status: Active Grant

• Current Assignee: Stmicroelectronics Design And Application S.R.O. (STMicroelectronics NV), STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Benenati, Giovanni, Ribellino, Calogero
• Primary Examiner(s): Tso; Edward
• Assistant Examiner(s): Fantu; Yalkew
• Application Number:
  US12/168,302
• Publication Number:
  US 20090015211A1
• Time in Patent Office: 960 Days
• Field of Search: 320/167
• US Class Current: 320/167
• CPC Class Codes: H02J 7/0019 using switched or multiplexed charge circuits
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps

Abstract

A device, such as a pump capacitor or an energy storing inductor, is charged by coupling it to a voltage source. Thereafter, the device is connected in parallel to one of the capacitors or capacitance cells to be charged, and the charging of the device and successive connections of it in parallel to a selected capacitor of the series of capacitors for charging it are replicated for all the capacitors of the series. The sequence of different connections of the device to the charge voltage source and to the selected one of the capacitors of the series is actuated through a plurality of coordinately controlled switches that establish distinct current circulation paths, according to a switched-capacitor or switched inductor techniques driven by respective periodic control signals that may be generated from a master clock signal.

Claims

1. A method of charging, at a same voltage of a charge voltage source, at least two capacitors coupled in series, the method comprising:

charging a charge circuit device comprising at least one of a pump capacitor and an inductor, by coupling the charge circuit device to the charge voltage source during first synchronized ON phases of a first and of a second periodic control signal;

coupling the charge circuit device in parallel to one of the capacitors during synchronized ON phases of the second and of a third periodic control signal;

charging again the charge circuit device during second synchronized ON phases of the first and second periodic control signals;

coupling the charge circuit device in parallel to another of the capacitors during synchronized ON phases of a fourth and a fifth periodic control signal; and

generating the periodic control signals from a master clock signal, the periodic control signals having periods that are multiples of a period of the master clock signal.

2. The method of claim 1 wherein the at least two capacitors comprises a number N of capacitors coupled in series;

and further comprising;

providing N−

1 pairs of periodic control signals for selecting any one of the number N of capacitors to be coupled in parallel to the charge circuit device; and

charging again the charge circuit device during second simultaneous ON phases of the first and second periodic control signals followed by a coupling of the charge circuit device in parallel to an additional capacitor of the number N of capacitors in response to an additional pair of the N−

1 pairs of periodic control signals.

3. The method of claim 1, further comprising comparing a voltage on the capacitors with a threshold value for carrying out charge cycles on the capacitors to be charged at the voltage of the charge voltage source, until reaching the threshold value.

4. The method of claim 1, further comprising sensing a voltage on each of the capacitors and charging any of the capacitors undercharged to the same voltage.

5. The method of claim 1, further comprising adjusting frequency and duty cycle between phases of the periodic control signals.

6. A method of charging, at a same voltage of a charge voltage source, at least two capacitors coupled in series, the method comprising:

charging a charge circuit device by coupling the charge circuit device to the charge voltage source during a first phase;

coupling the charge circuit device in parallel to one of the capacitors during a second phase;

charging again the charge circuit device during a third phase;

coupling the charge circuit device in parallel to another of the capacitors during a fourth phase; and

generating periodic control signals, to define the phases, based upon a clock signal.

7. The method of claim 6, wherein the charge circuit device comprises at least one of a pump capacitor and an inductor.

8. The method of claim 6, further comprising comparing a voltage on the capacitors with a threshold value for carrying out charge cycles on the capacitors to be charged at the voltage of the charge voltage source, until reaching the threshold value.

9. The method of claim 6, further comprising sensing a voltage on each of the capacitors and charging any of the capacitors undercharged to the same voltage.

10. The method of claim 6, further comprising adjusting frequency and duty cycle of the periodic control signals.

11. A device for charging, with a charge voltage source, at least two capacitors coupled in series, the device comprising:

a charge circuit device comprising at least one of a pump capacitor and an inductor for transferring electrical energy from the charge voltage source to a selected one of the capacitors coupled in series;

an array of circuit configuration switches, each controlled by a respective periodic control signal for coupling the charge circuit device to the charge voltage source and successively, in parallel, to the selected one of the capacitors;

a control signal circuit for generating the periodic control signals from a clock signal to operate the array of circuit configuration switches; and

a control block for monitoring a voltage on each of the capacitors, and to manage the control signal circuit to generate respective periodic control signals for coupling the charge circuit device to the selected capacitor.

12. The device of claim 11, wherein the control block compares a voltage on the capacitors with a threshold value for carrying out charge cycles on the capacitors to be charged at the voltage of the charge voltage source, until reaching the threshold value.

13. The device of claim 11, wherein the control block senses a voltage on each of the capacitors and controls charging of the capacitors to a same voltage.

14. The device of claim 11, wherein the control loop adjusts frequency and duty cycle of the periodic control signals.

15. A device for charging, with a charge voltage source, at least two capacitors coupled in series, the device comprising:

a charge circuit device for charging a selected one of the capacitors connected in series via the charge voltage source;

an array of circuit configuration switches, each controlled by a respective periodic control signal for selectively connecting the charge circuit device to the charge voltage source and the selected one of the capacitors;

a control signal circuit for generating the periodic control signals to operate the array of circuit configuration switches so that

the charge circuit device is connected to the charge voltage source during first synchronized ON phases of a first and of a second periodic control signal,

the charge circuit device is connected in parallel to one of the capacitors during synchronized ON phases of the second and of a third periodic control signal,

the charge circuit device is charged again during second synchronized ON phases of the first and second periodic control signals, and

the charge circuit device is connected in parallel to another of the capacitors during synchronized ON phases of a fourth and a fifth periodic control signal.

16. The device of claim 15, further comprising a control block for monitoring a voltage on each of the capacitors, and to manage the control signal circuit to generate respective periodic control signals for coupling the charge circuit device to the selected capacitor.

17. The device of claim 15, wherein the charge circuit device comprises at least one of a pump capacitor and an inductor.

18. The device of claim 15, wherein the control block compares a voltage on the capacitors with a threshold value for carrying out charge cycles on the capacitors to be charged at the voltage of the charge voltage source, until reaching the threshold value.

19. The device of claim 15, wherein the control block senses a voltage on each of the capacitors and controls charging of the capacitors to a same voltage.

20. The device of claim 15, wherein the control loop adjusts frequency and duty cycle of the periodic control signals.