Switching circuit for charge and discharge of multiple battery systems

• US 20040192407A1
• Filed: 04/16/2002
• Published: 09/30/2004
• Est. Priority Date: 04/16/2002
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Formenti, Jose Antonio Vieira
• Granted Patent: US 6,957,048 B2
• Time in Patent Office: Days
• US Class Current: 455/572
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence

Abstract

Multiple battery systems and switching networks are provided for portable electronic devices. A single switching cell is provided per battery and a load switch coupled to a battery power bus to achieve proper connectivity and isolation between batteries, a load and a charger. The single switching cells are configured as a back-to-back MOSFET switch devices. The charger is also coupled to the battery power bus and can be enabled when AC power to the portable electronic device is not available. The present invention facilitates selective connection of battery packs in a multiple battery system to a load or a charger, while still maintaining isolation between battery packs, the load and the charger.

Claims

1. A portable electronic device comprising:

a first switching cell coupled to a first battery on a first end and a battery power bus on a second end, the first switching cell being comprised of two back-to-back MOSFET devices;

a second switching cell coupled to a second battery on a first end and the battery power bus on a second end, the second switching cell being comprised of two back-to-back MOSFET devices;

a load switch coupled to the battery bus on a first end and a load on a second end;

a charger coupled to the battery bus; and

a DC supply connected to the load through a DC switch.

2. The portable electronic device of claim 1, the DC switch being one of a p-type MOSFET device and a n-type MOSFET device.

3. The portable electronic device of claim 1, the load switch being one of a p-type MOSFET device and a n-type MOSFET device.

4. The portable electronic device of claim 1, the two back-to-back MOSFET devices of the first switching cell and the second switching cell being n-type MOSFET devices.

5. The portable electronic device of claim 1, the two back-to-back MOSFET devices of the first switching cell and the second switching cell being p-type MOSFET devices.

6. The portable electronic device of claim 1, further comprising a control system that controls the switching of the first switching cell through a first control line, the second switching cell through a second control line and the load switch through a load control line.

7. The portable electronic device of claim 6, the control system controls the switching of the DC switch through a DC switch control line.

8. The portable electronic device of claim 6, the load control line also enables and disables the charger.

9. The portable electronic device of claim 1, the DC supply coupled to an AC/DC adapter that receives AC voltage and provides unregulated DC voltage to the DC supply, the DC supply provides regulated DC voltage to the load and the charger upon detection of AC power.

10. The portable electronic device of claim 1, further comprising N number of batteries and M number of switching cells comprised of two back-to-back MOSFET devices, the switching cells coupled to a respective battery on a first end and the battery power bus on a second end, N and M being integers greater than 2 having equal values, such that a single switching cell corresponds to a single battery.

11. A switching network for a multiple battery system comprising:

a first back-to-back MOSFET device connectable to a first rechargeable power source on a first end and a power bus on a second end;

a second back-to-back MOSFET device connectable to a second rechargeable power source on a first end and the power bus on a second end;

a load switch coupled to the power bus on a first end and a load on a second end;

a charger coupled to the power bus; and

a DC supply connected to the load through a DC switch.

12. The switching network of claim 11, the DC switch being one of a diode, a p-type MOSFET device and a N-type MOSFET device.

13. The switching network of claim 11, the load switch being one of a p-type MOSFET device and a N-type MOSFET device.

14. The switching network of claim 11, the first and the second back-to-back MOSFET devices being one of n-type MOSFET devices and p-type devices.

15. The switching network of claim 11, further comprising a first control line that controls the switching of the first back-to-back MOSFET device, a second control line that controls the switching of the second back-to-back MOSFET device and a third control line that controls the switching of the load switch.

16. The switching network of claim 11, further comprising a first control line that controls the switching of a first MOSFET device and a second control line that controls the switching of a second MOSFET device of the first back-to-back MOSFET device, a third control line that controls the switching of a third MOSFET device and a fourth control line that controls the switching of a fourth MOSFET device of the second back-to-back MOSFET device, and a fifth control line that controls the switching of the load switch.

17. The switching network of claim 16, further comprising a sixth control line that controls the switching of the DC switch.

18. The switching network of claim 11, further comprising M number of back-to-back MOSFET devices connectable to N number of respective rechargeable power sources on a first end and the battery power bus on a second end, N and M being integers greater than 2 having equal values, such that a single back-to-back MOSFET device corresponds to a single rechargeable power source.

19. A method for providing a multiple battery system, the method comprising:

coupling a first back-to-back MOSFET device to a first battery on a first end and a battery bus on a second end;

coupling a second back-to-back MOSFET device to a second battery on a first end and the battery bus on a second end;

coupling a load switch to the battery power bus on a first end and a load on a second end;

coupling a charger to the battery power bus; and

connecting a DC supply to the load through a DC switch and to the charger.

20. The method of claim 19, further comprising providing at least one control signal for each of the first back-to-back MOSFET device, the second back-to-back MOSFET device and the load switch.

21. The method of claim 20, the control signal that controls the load switch also enables and disables the charger.

22. The method of claim 20, further comprising a separate control signal that enables and disables the charger.

23. The method of claim 19, further comprising providing additional back-to-back MOSFET devices for each additional battery, each additional back-to-back MOSFET device coupled to the battery power bus on a first end and an additional battery on a second end.

24. A method of operating a switching network of a multiple battery system, the method comprising:

decoupling a load from a battery power bus by opening a load switch connected between the load and the battery power bus;

providing DC power to the load and a charger from a DC power supply;

providing charge from the charger to a battery power bus;

recharging a first battery by connecting the battery power bus to a first battery through closing a first back-to-back MOSFET device and opening a second back-to-back MOSFET device connecting the battery power bus to a second battery; and

recharging a second battery by connecting the battery power bus to the second battery through opening the first back-to-back MOSFET device and closing the second back-to-back MOSFET device.

25. The method of claim 24, further comprising:

determining that the DC supply is not available;

disabling the charger and connecting the load to the battery power bus; and

connecting one of the first battery and the second battery to the battery power bus powering the load by closing one of the first back-to-back MOSFET device and the second back-to-back MOSFET device.