Over-voltage protection circuit

• US 7,948,727 B2
• Filed: 05/07/2009
• Issued: 05/24/2011
• Est. Priority Date: 10/01/2001
• Status: Expired due to Fees

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: Mathew, Roshy Stan, Luong, Quang A., Madter, Richard C., Shiner, Andrew D., Schaaff, Carl D., Habicher, Michael F.
• Primary Examiner(s): PATEL, DHARTI HARIDAS
• Application Number:
  US12/436,992
• Publication Number:
  US 20090213512A1
• Time in Patent Office: 747 Days
• Field of Search: 361/91.1, 320/152, 320157-159, 320162-164
• US Class Current: 361/91.1
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00308 Overvoltage protection
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence

Abstract

An over-voltage protection circuit is disclosed herein for protection against over-voltage of an energy storage device while charging. The circuit operates within the operational limits of a battery-operated device, such as a mobile or handheld device. The over-voltage protection circuit comprises an over-voltage protection device, and an over-voltage protection controller. The controller allows current to flow to the over-voltage protection device only when an energy storage device is experiencing over-voltage. In allowing current to flow to the over-voltage protection device only when the voltage across the energy storage device is above a predetermined voltage, power conservation is achieved.

Claims

1. An over-voltage protection circuit for connection to a charging circuit for maintaining a voltage across a plurality of electrical energy storage devices at or below a predetermined voltage during charging, comprising:

a first electrical energy storage device connected from a top voltage rail to a primary junction;

a second electrical energy storage device connected from the primary junction to a bottom voltage rail, the first electrical energy storage device and the second electrical energy storage device charged by current flowing from the top rail through the first electrical energy storage device and the second electrical energy storage device to the bottom rail;

an inductor; and

a first switch and a second switch;

the over-voltage protection circuit to perform a first procedure in which a charge is drawn from the first electrical energy storage device through the inductor to energize the inductor, the inductor then to cause a current that charges the second storage device, the first procedure beginning when the first switch is closed;

the over-voltage protection circuit to perform a second procedure in which a charge is drawn from the second electrical energy storage device through the inductor to energize the inductor, the inductor then to cause a current that charges the first storage device, the second procedure beginning when the second switch is closed;

the inductor to be energized to less than saturation level;

a voltage sensor, the voltage sensor to close the first switch in response to the first electrical energy storage device being excessively charged and to close the second switch in response to the second electrical energy storage device being excessively charged; and

a dissipation controller to perform a third procedure in which a charge is discharged from the energized inductor upon detection of an over-voltage condition by the voltage sensor.

2. The over-voltage protection circuit of claim 1, claim 2, further comprising:

a first diode, the first diode and the first switch connected from the top rail to a secondary junction;

a second diode, the second diode and the second switch connected from the secondary junction to the bottom rail, with the inductor connected from the primary junction to the secondary junction;

the over-voltage protection circuit being configured in the first procedure to;

close the first switch to conduct current from the top rail, through the first switch and the inductor, to the primary junction to energize the inductor; and

open the first switch, causing the inductor to induce a temporary current to flow from the bottom rail through the second diode and the inductor, to the primary junction; and

the over-voltage protection circuit being configured in the second procedure to;

close the second switch to conduct current from the primary junction, through the second switch and the inductor, to the bottom rail to energize the inductor; and

open the second switch, causing the inductor to induce a temporary current to flow from the primary junction through the first diode and the inductor, to the top rail.

3. The circuit of claim 1, wherein the first electrical energy storage device is a capacitor.

4. The circuit of claim 1, wherein the first electrical energy storage device is a battery.

5. An over-voltage protection circuit for connection to a charging circuit for maintaining a voltage across a plurality of electrical energy storage devices at or below a predetermined voltage during charging, comprising:

a first electrical energy storage device connected from a top voltage rail to a primary junction;

a second electrical energy storage device connected from the primary junction to a bottom voltage rail, the first electrical energy storage device and the second electrical energy storage device charged by current flowing from the top rail through the first electrical energy storage device and the second electrical energy storage device to the bottom rail;

an inductor;

a first switch and a second switch; and

a dissipation controller to perform a dissipation procedure in which a charge is discharged from the energized inductor upon detection of an over-voltage condition by a voltage sensor;

the over-voltage protection circuit to perform a first procedure in which a charge is drawn from the first electrical energy storage device through the inductor to energize the inductor, the inductor then to cause a current that charges the second electrical energy storage device, the first procedure beginning when the first switch is closed; and

the over-voltage protection circuit to perform a second procedure in which a charge is drawn from the second electrical energy storage device through the inductor to energize the inductor, the inductor then to cause a current that charges the first electrical energy storage device, the second procedure beginning when the second switch is closed.

6. The over-voltage protection circuit of claim 5, further comprising:

a first diode, the first diode and the first switch connected from the top rail to a secondary junction;

a second diode, the second diode and the second switch connected from the secondary junction to the bottom rail, with the inductor connected from the primary junction to the secondary junction;

the over-voltage protection circuit being configured in the first procedure to;

close the first switch to conduct current from the top rail, through the first switch and the inductor, to the primary junction to energize the inductor; and

open the first switch, causing the inductor to induce a temporary current to flow from the bottom rail through the second diode and the inductor, to the primary junction; and

the over-voltage protection circuit being configured in the second procedure to;

close the second switch to conduct current from the primary junction, through the second switch and the inductor, to the bottom rail to energize the inductor; and

open the second switch, causing the inductor to induce a temporary current to flow from the primary junction through the first diode and the inductor, to the top rail.

7. The over-voltage protection circuit of claim 5, wherein the voltage sensor closes the first switch in response to the first storage device being excessively charged, and closes the second switch in response to the second storage device being excessively charged.

8. A method of operating an over-voltage protection circuit electrical circuit for charging a plurality of electrical energy storage devices that includes a first electrical energy storage device connected from a top voltage rail to a primary junction, a second electrical energy storage device connected from the primary junction to a bottom voltage rail, the first electrical energy storage device and the second electrical energy storage device charged by current flowing from the top rail through the first electrical energy storage device and the second electrical energy storage device to the bottom rail, an inductor, a first diode and a first switch, the first diode and the first switch connected from the top rail to a secondary junction, and a second diode and a second switch, the second diode and the second switch connected from the secondary junction to the bottom rail, with the inductor connected from the primary junction to the secondary junction, the method comprising:

performing a first procedure in which a charge is drawn from the first electrical energy storage device through the inductor to energize the inductor, the inductor then to cause a current that charges the second electrical energy storage device;

the first procedure including;

closing the first switch to conduct current from the top rail, through the first switch and the inductor to the primary junction to energize the inductor; and

opening the first switch to cause the inductor to induce a temporary current to flow from the bottom rail through the second diode and the inductor to the primary junction; and

performing a second procedure in which a charge is drawn from the second electrical energy storage device through the inductor, the inductor then to cause a current that charges the first electrical energy storage device;

the second procedure including;

closing the second switch to conduct current from the primary junction, through the inductor and the second switch, to the bottom rail to energize the inductor; and

opening the second switch to cause the inductor to induce a temporary current to flow from the primary junction through the inductor and the first diode to the top rail;

the over-voltage protection circuit being configured to perform the first procedure in response to the first electrical energy storage device being excessively charged and to perform the second procedure in response to the second electrical energy storage device being excessively charged; and

discharging the energized inductor upon detection of an over-voltage condition.

9. The method of claim 8, wherein the first electrical energy storage device is a capacitor.

10. The method of claim 8, wherein the first electrical energy storage device is a battery.