Battery full-charge detection for charge-and-play circuits

• US 8,035,354 B2
• Filed: 12/12/2006
• Issued: 10/11/2011
• Est. Priority Date: 12/16/2005
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: ST-Ericcson SA (Telefonaktiebolaget LM Ericsson)
• Inventors: Van Der Velden, Frank P. A., Groeneveld, Dirk
• Primary Examiner(s): DIAO, M BAYE
• Application Number:
  US12/097,690
• Publication Number:
  US 20080315845A1
• Time in Patent Office: 1,764 Days
• Field of Search: 320/128, 320/159
• US Class Current: 320/159
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence
• CPC Class Codes: H02J 7/00714 in response to battery charging or discharging current
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: H02J 7/007194 of the battery
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage

Abstract

The present invention relates to a battery charge circuit (100) in a charge-and-play mode capable to reliably determine the completion of a battery charging operation has been described. Such a determination takes into account the behavior of the battery charge circuit (100) with respect to the temperature, the activity of the circuitry (30) and the source current limitation. Thus, a distinction can be made between a decrease of the battery charge current ICHG below the end-of-charge current level caused by the full-charge state of the battery (20) and by the activation of temperature and current regulation circuits. Furthermore, the battery charge circuit (100) is also configured such that it can be warned both that the activity of the circuitry (30) is to be limited and, by a timer (800) measuring the time interval during which the battery charge current ICHG has been reduced to zero, that the battery (20) is being discharged.

Claims

1. A battery charge circuit configuration for operating a circuitry and simultaneously charging an associated battery separated from said circuitry comprising:

a first switching means, said first switching means being passed through by a first current which is charging said battery;

a first current sensor means, for detecting said first current;

a second current sensor means, for detecting a second current, said second current supplying said circuitry;

a first control unit, for controlling said first switching means, wherein said first control unit comprises;

a first input, said first input being connected to said first current sensor means in order to have a current level identical to said first current;

a second input, said second input being connected to said second current sensor means in order to have a current level identical to said second current;

a third input, said third input being connected to a node to which said battery is connected in order to have a voltage level identical to a voltage level across said battery; and

a fourth input, said fourth input having a current level which is a replica of said current level of said first input.

2. A battery charge circuit configuration according to claim 1, wherein:

said current level of said first input is compared to a reference charge current;

said second input and said fourth input are added together and the resulting current level corresponding to the summation is then compared to a reference source current; and

said voltage level of said third input is compared to a reference voltage.

3. A battery charge circuit configuration according to claim 2, wherein:

said reference charge current has a low current level corresponding to a end-of-charge current;

said reference source current corresponds to a maximum current level capable to be provided by said power supply means; and

said reference voltage has a high voltage level corresponding to a end-of-charge or full-charge voltage.

4. A battery charge circuit configuration according to claim 3, wherein said first control unit further comprises a completion validation unit, for determining whether said battery is fully charged, said completion determination being validated if each one of the following criteria is satisfied:

said voltage level of said third input is greater than or equal to said reference voltage; and

said current level of said first input is less than or equal to said reference charge current; and

said resulting current level is less than or equal to said reference source current.

5. A battery charge circuit configuration according to claim 4, wherein said battery charge circuit configuration further comprises:

a second switching means, said second switching means being passed through by said second current;

a second control unit for controlling said second switching means, wherein said second control unit comprises at least;

a sixth input, said sixth input having a current level which is a replica of said current level of said second input.

6. A battery charge circuit configuration according to claim 5, wherein:

said sixth input is compared to said reference source current.

7. A battery charge circuit configuration according to claim 6, wherein said second control unit generates a sequence of interrupt signals comprising:

a first interrupt signal, said first interrupt signal being generated when said current level of said sixth input is greater than or equal to said reference source current; and

a second interrupt signal, said second interrupt signal being then generated when said current level of said sixth input is less than said reference source current.

8. A battery charge circuit configuration according to claim 7, wherein said second control unit further comprises a timer for measuring a time interval during which said first current has been reduced to zero, said timer being put in a pause mode by said first interrupt signal and leaving said pause mode by said second interrupt signal or inversely.

9. A battery charge circuit configuration according to claim 8, wherein any one of said first and second control units is a digital and analog controller means.

10. A battery charge circuit configuration according to claim 9, wherein said battery charge circuit configuration is an integrated circuit made from a single silicon implementation.

11. A battery charge circuit configuration according to claim 10, wherein said battery charge circuit configuration further comprises:

a first temperature sensor means, for detecting a first temperature of said first switching means.

12. A battery charge circuit configuration according to claim 11, wherein said first control unit further comprises:

a fifth input, said fifth input being connected to said first temperature sensor means in order to have a temperature level identical to said first temperature.

13. A battery charge circuit configuration according to claim 12, wherein said temperature level of said fifth input is compared to a first reference temperature.

14. A battery charge circuit configuration according to claim 13, wherein said first reference temperature corresponds to a maximum temperature level to be not exceeded by said first switching means.

15. A battery charge circuit configuration according to claim 14, wherein said completion determination by said completion validation unit is further validated if the following criteria is additionally satisfied:

said temperature level of said fifth input is less than or equal to said first reference temperature.

16. A battery charge circuit configuration according to claim 15, wherein said second control unit further comprises:

a seventh input, said seventh input being connected to a second temperature sensor means in order to have a temperature level identical to a second temperature, said second temperature sensor means detecting a second temperature of said second switching means.

17. A battery charge circuit configuration according to claim 16, wherein:

said seventh input is compared to a second reference temperature.

18. A battery charge circuit configuration according to claim 17, wherein said second reference temperature has a maximum temperature level to be not exceeded by said second switching means.

19. A battery charge circuit configuration according to claim 18, wherein said second control unit generates a third interrupt signal for warning said battery charge circuit that a load of said circuitry cannot increase, said third interrupt signal being generated when said temperature level of said seventh input is greater than or equal to said second reference temperature.

20. A battery charge circuit configuration according to claim 15, wherein each one of said reference charge current, said reference source current, said first and second reference temperatures and said reference voltage, is a value set or programmable.

21. A battery charge circuit configuration according to claim 20, wherein said first and second reference temperatures are identical and equal to a temperature of a die on which said integrated circuit is implemented.

22. A detection method for detecting a battery end-of-charge condition in a battery charge circuit which operates a circuit and simultaneously charges an associated battery separated from said circuit, comprising at least the following steps:

detecting a voltage level across said battery being charged;

comparing said voltage level across said battery to a reference voltage;

detecting a first current, said first current charging said battery;

comparing said first current to a reference charge current;

detecting a second current, said second current supplying said circuitry;

adding together said first and second currents;

comparing the resulting current level corresponding to said summation to a reference source current.

23. A detection method for detecting a battery end-of-charge condition according to claim 22, wherein said method further comprises a step of:

validating said battery end-of-charge condition, said battery end-of-charge condition being validated when;

said voltage level across said battery is greater than or equal to said reference voltage; and

said first current is less than or equal to said reference charge current; and

said resulting current level is less than or equal to said reference source current.

24. A detection method for detecting a battery end-of-charge condition according to claim 23, wherein said method further comprises the steps of:

generating a first interrupt signal, said first interrupt signal being generated when said second current is greater than or equal to said reference source current;

generating a second interrupt signal, said second interrupt signal being generated after said first interrupt signal and when said second current is less than said reference source current.

25. A detection method for detecting a battery end-of-charge condition according to claim 24, wherein said method further comprises a step of:

measuring a time interval, said time interval starting from said generation of said first interrupt signal and ending with said generation of said second interrupt signal or inversely.

26. A detection method for detecting a battery end-of-charge condition according to claim 25, wherein said method further comprises the steps of:

detecting a first temperature, said first temperature being a temperature of a first switching means through which said first current flows;

comparing said first temperature to a first reference temperature.

27. A detection method for detecting a battery end-of-charge condition according to claim 26, wherein said method further comprises the steps of:

detecting a second temperature, said second temperature being a temperature of a second switching means through which said second current flows;

comparing said second temperature to a second reference temperature;

comparing said second current to said reference source current.

28. A detection method for detecting a battery end-of-charge condition according to claim 27, wherein said method further comprises a step of:

warning said battery charge circuit that a load of said circuitry cannot increase.