Circuits capable of trickle precharge and/or trickle discharge

• US 7,180,268 B2
• Filed: 04/27/2004
• Issued: 02/20/2007
• Est. Priority Date: 03/25/2004
• Status: Active Grant

• Current Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Original Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Inventors: Li, Guoxing, Liu, Liusheng, Denning, Bruce S.
• Primary Examiner(s): Tso; Edward H.
• Application Number:
  US10/832,621
• Publication Number:
  US 20050212484A1
• Time in Patent Office: 1,029 Days
• Field of Search: 320/134, 320/135, 320/136, 320/158, 320/108
• US Class Current: 320/134
• 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
• CPC Class Codes: H02J 7/0069 Charging or discharging for charge maintenance, battery initiation or rejuvenation

Abstract

Battery charging circuitry and systems are provided. One embodiment may include at least one switch having a full conduction state and a controllable conduction state and switch control circuitry capable of sensing a condition. The switch control circuitry may further be capable of generating at least one control signal capable of controlling the conduction state of the switch based on, at least in part, the sensed condition.

Claims

1. An apparatus comprising:

a switch; and

switch control circuitry configured to control said switch in a full conduction state and a controllable conduction state, said switch control circuitry is configured to control said switch in said controllable conduction state by comparing an output voltage of said switch to a reference voltage and generating a control signal capable of controlling said conduction state of said switch, said switch control circuitry is further configured to force said output voltage of said switch to approximately equal said reference voltage and to provide a gain to said control signal to cause said switch to operate in a saturation region.

2. The apparatus of claim 1, wherein said switch comprises a charge switch to control charge current to a battery, wherein when a charge state of said battery is below a threshold charge, said switch control circuitry controls said switch in said controllable conduction state thereby allowing a trickle charge current to flow from a power source to said battery.

3. The apparatus of claim 2, wherein when said charge state of said battery is above said threshold charge, said switch control circuitry controls said switch in said full conduction state thereby allowing a full charge current to flow from said power source to said battery, said full charge current being greater than said trickle charge current.

4. The apparatus of claim 1, wherein said switch comprises a discharge switch to control discharge current provided from an associated battery, wherein when said battery experiences a discharge fault condition said switch control circuitry controls said switch in said controllable conduction state thereby allowing a trickle discharge current to flow from said battery.

5. The apparatus of claim 4, wherein in an absence of said fault condition said switch control circuitry controls said switch in said full conduction state thereby allowing a full discharge current to flow from said battery, said full discharge current being greater than said trickle discharge current.

6. The apparatus of claim 4, wherein said battery experiences said fault condition if a discharging current level provided by said battery is greater than a fault current threshold.

7. A system, comprising:

a battery pack comprising at least one rechargeable battery cell;

a switch; and

switch control circuitry configured to control said switch in a full conduction state and a controllable conduction state, said switch control circuitry is configured to control said switch in said controllable conduction state by comparing an output voltage of said switch to a reference voltage and generating a control signal capable of controlling said conduction state of said switch, said sensed condition, said switch control circuitry is further configured to force said output voltage of said switch to approximately equal said reference voltage and to provide a gain to said control signal to cause said switch to operate in a saturation region.

8. The system of claim 7, wherein said switch comprises a charge switch to control charge current to said at least one battery cell, wherein when a charge state of said at least one battery cell is below a threshold charge, said switch control circuitry controls said switch in said controllable conduction state thereby allowing a trickle charge current to flow from a power source to said at least one battery cell.

9. The system of claim 8, wherein when said charge state of said at least one battery cell is above said threshold charge, said switch control circuitry controls said switch in said full conduction state thereby allowing a full charge current to flow from said power source to said at least one battery cell, said full charge current being greater than said trickle charge current.

10. The system of claim 7, wherein said switch comprises a discharge switch to control discharge current provided from said at least one battery cell, wherein when said battery experiences a discharge fault condition said switch control circuitry controls said switch in said controllable conduction state thereby allowing a trickle discharge current to flow from said at least one battery cell.

11. The system of claim 10, wherein in an absence of said fault condition said switch control circuitry controls said switch in said full conduction state thereby allowing a full discharge current to flow from said at least one battery cell, said full discharge current being greater than said trickle discharge current.

12. The system of claim 10, wherein said at least one battery cell experiences said fault condition if a discharging current level provided by said battery is greater than a fault current threshold.

13. A method, comprising:

providing a switch;

providing a battery;

controlling the conduction state of said switch comprising;

a) comparing an output voltage of said switch to a reference voltage;

b) generating a control signal capable of controlling said conduction state of said switch;

c) forcing said output voltage of said switch to be approximately equal to said reference voltage; and

d) providing a gain of said control signal to cause said switch to operate in a saturation region.

14. The method of claim 13, further comprising:

controlling the conduction state of said switch to operate in said saturation region to permit said battery to generate a controllable trickle discharge current.

15. The method of claim 13, further comprising:

controlling the conduction state of a said switch to operate in said saturation region to permit said battery to receive a controllable trickle charge current.