Circuit for regulating current to multiple batteries in a battery charger

• US 6,828,759 B1
• Filed: 05/15/2003
• Issued: 12/07/2004
• Est. Priority Date: 05/15/2003
• Status: Active Grant

• Current Assignee: Amperex Technology Limited (TDK Corporation)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Riley, Marc B., Ramsden, Martin H., Xiong, Seng P.
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US10/439,257
• Publication Number:
  US 20040227487A1
• Time in Patent Office: 572 Days
• Field of Search: 320/116, 320/128, 320/133, 320/137, 320/140, 320/145
• US Class Current: 320/116
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence

Abstract

A charging circuit for regulating current to a plurality of batteries is provided. The regulation is performed by a single control signal that is optionally scaled by resistor dividers. Switches coupled to the resistor dividers allow a microprocessor to actuate a particular resistor divider, thereby scaling the current flowing through a corresponding battery. As such, a single control signal, like a pulse width modulated signal, may be used to cause different currents to flow to different batteries, thereby leaving other output pins of the microprocessor open for other functions.

Claims

1. A circuit for charging multiple batteries, the circuit comprising:

a. a means for generating an adjustable control signal;

b. a means for regulating current;

c. a means for scaling the adjustable control signal, the means for scaling the adjustable control signal being coupled between the means for generating and the means for regulating; and

d. a means of actuating the means for scaling;

wherein when the means of actuating is actuated, the means for scaling reduces the adjustable control signal by a factor between 0 and 1.

2. The circuit of claim 1, wherein the means for scaling the adjustable control signal comprises a resistor divider.

3. The circuit of claim 2, wherein the means for actuating the means for scaling comprises a switch.

4. The circuit of claim 3, wherein the switch is selected from the group consisting of transistors, relays, circuit breakers, positive temperature coefficient devices, and fuses.

5. The circuit of claim 4, wherein the means for generating an adjustable control signal comprises a microprocessor.

6. The circuit of claim 5, wherein the adjustable control signal comprises a pulse width modulated signal.

7. The circuit of claim 6, wherein the means of actuating is controllable by the microprocessor.

8. The circuit of claim 2, wherein the resistor divider comprises a first resistor coupled serially between the means for generating and the means for regulating, further comprising a second resistor coupled serially between the first resistor and the means for actuating.

9. The circuit of claim 8, wherein the means for actuating comprises a transistor coupled serially between the second resistor and a ground node.

10. A circuit for charging multiple batteries, the circuit comprising:

a. a means for generating an adjustable control signal;

b. at least two means for regulating current;

c. at least two means for scaling the adjustable control signal, the at least two means for scaling the adjustable control signal being coupled between the at least two means for generating and the at least two means for regulating, respectively; and

d. at least two means of actuating the at least two means for scaling;

wherein when the means of actuating is actuated, the means for scaling reduces the adjustable control signal by a factor between 0 and 1.

11. The circuit of claim 10, wherein when a first battery and a second battery are coupled to the circuit, further wherein the first battery has priority over the second battery, a first means of actuating is actuated and a second means of actuating is not actuated.

12. The circuit of claim 11, wherein the at least two means for scaling the adjustable control signal comprise a first and a second resistor divider.

13. The circuit of claim 12, wherein the at least two means for actuating the means for scaling comprise a first and a second switch.

14. The circuit of claim 13, wherein the first and second switches are selected from the group consisting of transistors, relays, circuit breakers, positive temperature coefficient devices, and fuses.

15. The circuit of claim 14, wherein the means for generating an adjustable control signal comprises a microprocessor.

16. The circuit of claim 15, wherein the adjustable control signal comprises a pulse width modulated signal.

17. The circuit of claim 16, wherein the at least two means of actuating are controllable by the microprocessor.