Low noise charging method and device for portable devices

• US 20060113962A1
• Filed: 04/25/2005
• Published: 06/01/2006
• Est. Priority Date: 12/01/2004
• Status: Active Grant

• Current Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Original Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Inventors: Spiridon, Constantin
• Granted Patent: US 7,573,240 B2
• Time in Patent Office: Days
• US Class Current: 320/139
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: H02J 7/00711 with introduction of pulses during the charging process

Abstract

A method is used for charging a battery. According to the method of the present invention, the battery is first charged to a predetermined voltage at a substantially constant current. Then, the charging current is disabled. A pulsing current is applied to the battery for charging the battery.

Claims

1. A method for charging a battery, comprising:

charging the battery to a predetermined voltage with a charging current;

disabling the charging current;

applying a pulsing current to the battery;

measuring a battery voltage between pulses of the pulsing current;

disabling the pulsing current when the battery voltage that is measured is higher than the predetermined voltage;

remeasuring the battery voltage; and

re-applying the pulsing current to the battery when the battery voltage that is remeasured goes below the predetermined voltage.

2. The method of claim 1, further comprising:

coupling an external power source to the battery for providing the charging current and the pulsing current to the battery.

3. The method of claim 1, wherein the step of applying a pulsing current to the battery further comprises:

generating a signal having a plurality of pulses; and

applying a voltage to the battery in response to the pulses of the signal.

5. The method of claim 3, further comprising:

stopping charging the battery when the battery voltage that is remeasured is higher than the predetermined voltage for a predetermined period of time.

6. The method of claim 1, wherein the step of applying a pulsing current to the battery further comprises:

generating a signal having a plurality of periodic pulses; and

applying the pulsing voltage to the battery in response to the pulses of the signal.

7. The method of claim 6, wherein the period is approximately 1 Hz.

8. The method of claim 1, further comprising:

charging the battery through a bypass circuit when a battery voltage of the battery is lower than a lower threshold voltage for pre-charging the battery.

9. The method of claim 1, further comprising:

measuring and remeasuring the battery voltage when the charging current is substantially zero.

10. The method of claim 1, further comprising:

using a single switching mechanism to perform the steps of charging the battery to a predetermined voltage, disabling the charging current; and

applying a pulsing current to the battery.

4. (canceled)

11. A system for charging a battery comprising:

a first comparator for determining whether a battery voltage of the battery is lower than a first predetermined voltage;

a switch for coupling an external power source to the battery; and

a timer for generating a signal having a plurality of pulses;

wherein the switch is enabled until the battery voltage is higher than the first predetermined voltage and then the switch is enabled in response to the pulses of the signal.

12. The system of claim 11, wherein the duty cycle ratio of the pulse is from about 60% to about 80%.

13. The system of claim 11, wherein the pulses of the signal are periodic.

14. The system of claim 11, further comprising:

a second comparator for determining whether the battery voltage is lower than a second predetermined voltage;

a precharger for charging the battery when the battery voltage is lower than the second predetermined voltage.

15. The system of claim 14, further comprising:

a third comparator for determining whether the battery voltage is higher than a third predetermined voltage;

a stopping device for disabling the switch when the battery voltage is higher than the third predetermined voltage so as to protect the battery from overcharging.

16. The system of claim 11, further comprising:

a discharging logic block for further enabling and disenabling the switch for controlling the discharge of the battery.

17. The system of claim 11, further comprising:

a device for stating where the voltage of the battery has been over the predetermined voltage.

18. The system of claim 11, further comprising:

a memory device for memorizing the voltage of the battery between the pulses for a certain period of time.

19. The system of claim 18, further comprising:

a state device coupling to the timer and the memory device to show the state of the system.

20. The system of claim 11, further comprising;

a bi-directional controller for enabling the switch when the external power source is removed from the switch and an external battery-driven device is coupled to the switch.

21. A method for charging a battery, comprising:

coupling a substantially continuous charging current to the battery until a battery voltage is higher than a predetermined voltage;

generating a discrete voltage having a plurality of voltage pulses;

coupling the plurality of voltage pulses to the battery;

measuring a battery voltage of the battery between pulses of the plurality of voltage pulses;

disabling the discrete voltage when the battery voltage that is measured is higher than the predetermined voltage;

remeasuring the battery voltage; and

re-coupling the voltage pulses to the battery when the battery voltage that is remeasured goes below the predetermined voltage.

22. The method of claim 21, wherein the disabling the discrete voltage further comprises:

decoupling the voltage pulses from the battery when the voltage of the battery is higher than the predetermined voltage.

23. The method of claim 21, further comprising:

periodically measuring the battery voltage during the low level of the voltage pulses;

measuring the length of the battery voltage being higher than the predetermined voltage; and

completing the charging of the battery when the battery voltage is higher than the predetermined voltage for a predetermined period of time.