Selector circuit for power management in multiple battery systems

• US 20040160213A1
• Filed: 02/11/2003
• Published: 08/19/2004
• Est. Priority Date: 02/11/2003
• Status: Active Grant

• Current Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Original Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Inventors: Bucur, Constantin, Niculae, Marian, Stanesti, Vlad Popescu
• Granted Patent: US 6,977,482 B2
• Time in Patent Office: Days
• US Class Current: 320/116
• CPC Class Codes: H02J 7/0018 using separate charge circuits
• 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 7/34 Parallel operation in networks using both storage and other dc sources, e.g. providing buffering H02J7/14 takes precedence
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A selector circuit configured to select among a DC power source and a plurality of batteries for an electronic device. The selector circuit is responsive to an output signal from an associated power management unit. The selector circuit is further configured to permit parallel operation of two or more of the batteries. The selector circuit may further act to independently verify power conditions and override any instructions from the PMU in certain instances to enhance power supply safety and battery life. A power supply block including the selector circuit and an electronic device including the power supply block is also provided. The selector circuit may be integrated with a charging circuit on one integrated circuit.

Claims

1. A controller for a selector circuit configured to select among a DC power source and a plurality of batteries for an electronic device, said controller comprising:

a selector output circuit configured to provide selector output signals that control selection among said DC power source and said plurality of batteries, said selector output circuit providing said selector output signals in response to a power management unit (PMU) output signal from a PMU configured to run a power management routine.

2. The controller of claim 1, wherein said selector output circuit provides selector output signals that select parallel operation of at least a first battery and a second battery of said plurality of batteries in response to said PMU output signal indicating a desired parallel operation of said first and second battery.

3. The controller of claim 2, wherein said controller comprises a battery voltage comparator configured to compare a first voltage level of said first battery with a second voltage level of said second battery and provide a battery voltage comparison signal, said selector output circuit providing selector output signals in response to said battery voltage comparison signal to select said desired parallel operation if said battery voltage comparison signal is representative of said first voltage level being within a predetermined voltage limit of said second voltage level.

4. The controller of claim 2, wherein said selector output circuit provides selector output signals that select either said first battery or said second battery if said battery voltage comparison signal is representative of said first voltage level not being within a predetermined voltage limit of said second voltage level, thereby overriding said PMU output signal indicating said desired parallel operation.

5. The controller of claim 4, wherein said first and second batteries are rechargeable batteries, and wherein said battery voltage comparison signal further indicates which of said first voltage level and said second voltage level is lowest, said selector output circuit providing selector output signals that select said first or second battery with said lowest voltage level for recharging if said DC source is present.

6. The controller of claim 4, wherein said battery voltage comparison signal further indicates which of said first voltage level and said second voltage level is highest, said selector output circuit providing selector output signals that select said first or second battery with said highest voltage level for discharging if said DC source is not present.

7. The controller of claim 1, further comprising a first comparator, said first comparator configured to compare a first signal representative of a voltage level of said DC power source with a first threshold level and provide a DC source enable signal representative of a difference between said first signal and said first threshold level, said selector output circuit providing selector output signals to select said DC source and deselect said plurality of batteries if said DC source enable signal indicates said voltage level of said DC source is greater than said first threshold level.

8. The controller of claim 1, wherein said PMU output signal represents a desired selection of at least one of said plurality of batteries, and said selector output circuit provides selector output signals to select said DC source and deselect said plurality of batteries if said DC source enable signal indicates said voltage level of said DC source is greater than said first threshold level, thereby overriding said PMU output signal.

9. The controller of claim 1, wherein said controller comprises a power crisis circuit, said power crises circuit configured to accept an input signal based on said PMU output signal and provide a diode mode signal upon detection of a power crises condition, said selector output circuit responsive to said diode mode signal to select each of said DC power source and said plurality of batteries such that said DC power source and each of said plurality of batteries is coupled in series to an associated diode thereby permitting only one of said DC power source or said plurality of batteries with a voltage level higher than a remainder of said power sources to supply said electronic system.

10. The controller of claim 9, wherein a system check signal representative of a voltage level of said electronic device less than a minimum voltage threshold level represents one said power crisis condition.

11. The controller of claim 9, wherein said selector output circuit provides an alert signal upon detection of said power crisis condition.

12. A power supply block for monitoring and providing power to an electronic device from a DC power source and a plurality of rechargeable batteries, and for recharging any of said plurality of rechargeable batteries from said DC power source, said power supply block comprising:

a charging circuit configured to control charging of said plurality of rechargeable batteries from said DC power source; and

a selector circuit configured to select at least one of said DC source and said plurality of batteries in response to a power management unit (PMU) output signal from a PMU configured to run a power management routine.

13. The power supply block of claim 12, wherein said charging circuit and said selector circuit are integrated onto one integrated circuit.

14. An electronic device that may be powered by one or more of a plurality of rechargeable batteries or a DC power source, said electronic device comprising:

a power management unit configured to run a power management routine;

a charging circuit configured to control charging of said plurality of rechargeable batteries; and

a selector circuit configured to select at least one of said DC source and said plurality of batteries in response to a power management unit (PMU) output signal from said PMU.

15. The electronic device of claim 14, wherein said charging circuit and said selector circuit are integrated onto one integrated circuit.

16. The electronic device of claim 14, wherein selector circuit comprises a selector output circuit configured to provide selector output signals that select parallel operation of at least a first battery and a second battery of said plurality of rechargeable batteries in response to said PMU output signal indicating a desired parallel operation of said first and second battery.

17. The electronic device of claim 16, wherein said selector circuit comprises a battery voltage comparator configured to compare a first voltage level of said first battery with a second voltage level of said second battery and provide a battery voltage comparison signal, said selector output circuit providing selector output signals in response to said battery voltage comparison signal to select said desired parallel operation if said battery voltage comparison signal is representative of said first voltage level being within a predetermined voltage limit of said second voltage level.

18. The electronic device of claim 16, wherein said selector output circuit provides selector output signals that select either said first battery or said second battery if said battery voltage comparison signal is representative of said first voltage level not being within a predetermined voltage limit of said second voltage level, thereby overriding said PMU output signal indicating said desired parallel operation.

19. The electronic device of claim 18, wherein said battery voltage comparison signal further indicates which of said first voltage level and said second voltage level is lowest, said selector output circuit providing selector output signals that select said first or second battery with said lowest voltage level for recharging if said DC source is present.

20. The electronic device of claim 18, wherein said battery voltage comparison signal further indicates which of said first voltage level and said second voltage level is highest, said selector output circuit providing selector output signals that select said first or second battery with said highest voltage level for discharging if said DC source is not present.

21. The electronic device of claim 14, said selector circuit further comprising a first comparator, said first comparator configured to compare a first signal representative of a voltage level of said DC power source with a first threshold level and provide a DC source enable signal representative of a difference between said first signal and said first threshold level, said selector output circuit providing selector output signals to select said DC source and deselect said plurality of batteries if said DC source enable signal indicates said voltage level of said DC source is greater than said first threshold level.

22. The electronic device of claim 14, wherein said PMU output signal represents a desired selection of at least, one of said plurality of batteries, and said selector output circuit provides selector output signals to select said DC source and deselect said plurality of batteries if said DC source enable signal indicates said voltage level of said DC source is greater than said first threshold level, thereby overriding said PMU output signal.

23. The electronic device of claim 14, wherein said selector circuit comprises a power crisis circuit, said power crises circuit configured to accept an input signal based on said PMU output signal and provide a diode mode signal upon detection of a power crises condition, said selector output circuit responsive to said diode mode signal to select each of said DC power source and said plurality of batteries such that said DC power source and each of said plurality of batteries is coupled in series to an associated diode thereby permitting only one of said DC power source or said plurality of batteries with a voltage level higher than a remainder of said power sources to supply said electronic device.

24. The electronic device of claim 23, wherein a system check signal representative of a voltage level of said electronic device less than a minimum voltage threshold level represents one said power crisis condition.

25. The electronic device of claim 23, wherein said selector output circuit provides an alert signal upon detection of said power crisis condition.

26. A controller for a selector circuit configured to select among a DC power source and a plurality of batteries for an electronic device, said controller comprising:

a first comparator configured to compare a first signal representative of a voltage level of said DC power source with a first threshold level and provide a DC power source enable signal representative of a difference between said first signal and said first threshold level;

a second comparator configured to compare said first signal representative of said voltage level of said DC power source with a second threshold level and provide a charge possible threshold signal representative of a difference between said first signal and said second threshold level;

a third comparator configured to compare a third signal representative of a voltage level of said electronic device with a third threshold level and provide a third signal representative of a difference between said third signal and said third threshold level;

a fourth comparator configured to compare a first voltage level of a first battery with a second voltage level of a second battery and to provide a fourth signal representative of a difference between said first voltage level of said first battery and said second voltage level of said second battery;

a parallel battery use enable circuit configured to receive said fourth signal and provide a parallel battery use enable signal in response to said fourth signal;

a charge enable circuit configured to accept said second signal and provide a charge enable signal in response to said second signal;

a power crisis circuit configured to accept at least said third signal, said parallel battery use enable signal, and said DC power source enable signal and configured to provide a diode mode signal; and

a selector output circuit configured to provide selector output signals that control selection among said DC power source and said plurality of batteries, said selector output circuit providing said selector output signals in response to a power management unit (PMU) output signal from a PMU, said charge possible threshold signal, said diode mode signal, said parallel battery use enable signal, and said DC power source enable signal.

27. A selector circuit configured to select at least one of a plurality of power sources for an electronic device in response to an output signal from a power management unit (PMU) configured to run a power management routine.

28. The selector circuit of claim 27, wherein said plurality of power sources comprises a DC power source and a plurality of batteries.

29. The selector circuit of claim 27, wherein said output signal from said PMU is representative of a desired parallel operation of at least a first battery and second battery of said plurality of batteries, and said selector circuit is further configured to select said first battery and second battery for said parallel operation in response to said output signal.

30. A method of ensuring safe operation of batteries in parallel, said method comprising the steps of:

receiving a control signal from an associated power management unit representative of a desired parallel use of at least a first battery and a second battery;

determining a difference between a first voltage level of said first battery and a second voltage level of said second battery;

comparing said difference to a difference threshold level; and

overriding said control signal from said associated power management unit by permitting operation of only said first battery or said second battery if said difference is greater than said difference threshold level.

31. The method of claim 30, further comprising the step of determining which of said first voltage level from said first battery or said second voltage level from said second battery is lowest.

32. The method of claim 31, wherein said first and second batteries are rechargeable batteries, and wherein said method further comprises the step of charging said first battery or said second battery having said lowest voltage level.

33. The method of claim 30, further comprising the step of determining which of said first voltage level from said first battery or said second voltage level from said second battery is highest.

34. The method of claim 33, further comprising the step of discharging said first battery or said second battery having said highest voltage level.