Charging control semiconductor integrated circuit and secondary battery charging apparatus using the same

• US 7,705,563 B2
• Filed: 02/16/2007
• Issued: 04/27/2010
• Est. Priority Date: 02/17/2006
• Status: Expired due to Fees

• Current Assignee: RICOH Electronic Devices Co., Ltd. (Nisshinbo Holdings Incorporated)
• Original Assignee: Ricoh Company Limited
• Inventors: Ibaraki, Tohru
• Primary Examiner(s): Assouad; Patrick J
• Assistant Examiner(s): DIAO, M BAYE
• Application Number:
  US11/707,449
• Publication Number:
  US 20070216357A1
• Time in Patent Office: 1,166 Days
• Field of Search: 320/128, 320/134, 320/136, 320/158, 320/159
• US Class Current: 320/128
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries

Abstract

A charging control semiconductor integrated circuit used in a charging apparatus for a secondary battery includes first and second terminals. The first terminal is configured to output a control signal to a first charging transistor in the charging apparatus. The second terminal is configured to output a control signal to a second charging transistor in the charging apparatus. Further, the first and second charging transistors are separately controlled on the basis of a voltage across the first charging transistor, a voltage across the second charging transistor, and a voltage of the secondary battery.

Claims

1. A charging control semiconductor integrated circuit for a charging apparatus that performs one of constant current charging and constant voltage charging to charge a secondary battery by supplying charging currents from first and second charging transistors to the secondary battery through first and second charging current detecting resistors, respectively, the charging control semiconductor integrated circuit comprising:

a first terminal to output a first control signal to the first charging transistor; and

a second terminal to output a second control signal to the second charging transistor,

wherein the first and second charging transistors are separately controlled on the basis of a voltage across the first charging transistor, a voltage across the second charging transistor, and a voltage of the secondary battery.

2. The charging control semiconductor integrated circuit according to claim 1, further comprising:

a first charging-current-detecting circuit section configured to detect a first value of a first charging current from the first charging transistor on the basis of the voltage across the first charging current detecting resistor, and generate and output a first charging current value signal representing the detected first value of the first charging current;

a second charging-current-detecting circuit section configured to detect a second value of a second charging current from the second charging transistor on the basis of the voltage across the second charging current detecting resistor, and generate and output a second charging current value signal representing the detected second value of the second charging current;

a battery-voltage-detecting circuit section configured to detect a battery voltage as the voltage of the secondary battery, and generate and output a detected battery voltage signal representing the detected battery voltage;

a first charging-control circuit section configured to perform, on the basis of the first charging current value signal from the first charging-current-detecting circuit section and the detected battery voltage signal from the battery-voltage-detecting circuit section, one of(i) constant current charging allowing the first charging transistor to output a given first charging current, or (ii) constant voltage charging allowing the first charging transistor to output the first charging current so that the battery voltage is constant at a given value; and

a second charging-control circuit section configured to perform, on the basis of the second charging current value signal from the second charging-current-detecting circuit section and the detected battery voltage signal from the battery-voltage-detecting circuit section, one of(i) constant current charging allowing the second charging transistor to output a given second charging current, or (ii) constant voltage charging allowing the second charging transistor to output the second charging current so that the battery voltage is constant at a given value.

3. The charging control semiconductor according to claim 2, wherein the first charging-control circuit section includes:

a first constant-current-charging control circuit configured to control, on the basis of the first charging current value signal from the first charging-current-detecting circuit section, the first charging transistor to output the first charging current; and

a first constant-voltage-charging control circuit configured to control, on the basis of the detected battery voltage signal from the battery-voltage-detecting circuit section, the first charging transistor to output the first charging current so that the battery voltage is constant at a given value.

4. The charging control semiconductor integrated circuit according to claim 3,

wherein the first constant-current-charging control circuit includes:

a first operational amplifier circuit configured to amplify a difference voltage between the first charging current value signal from the first charging current detecting control circuit section and a given first reference voltage, and output the amplified difference voltage as a first amplified difference voltage signal; and

a first transistor having a first control electrode, the first amplified difference voltage signal from the first operational amplifier circuit being input through said first control electrode; and

the first constant-voltage-charging control circuit includes;

a second operational amplifier circuit configured to amplify a difference voltage between the detected battery voltage signal from the battery-voltage-detecting circuit section and a given second reference voltage, and output the amplified difference voltage as a second amplified difference voltage signal; and

a second transistor having a second control electrode, the second amplified difference voltage signal from the second operational amplifier circuit being input through said second control electrode; and

wherein the first and second transistors are connected in series between the first control electrode of the first charging transistor and a portion having a given voltage.

5. The charging control semiconductor integrated circuit according to claim 2, wherein the second charging current generated and output by the second charging-control circuit section is proportional to the first charging current.

6. The charging control semiconductor integrated circuit according to claim 4, wherein the second charging-control circuit section includes:

a second constant-current-charging control circuit configured to control, on the basis of the second charging current value second charging current value signal from the second charging-current-detecting circuit section, the second charging transistor to output the second charging current; and

a second constant-voltage-charging control circuit configured to control, on the basis of the detected battery voltage signal from the battery-voltage-detecting circuit section, the second charging transistor to output the second charging current so that the battery voltage is constant at a given value.

7. The charging control semiconductor integrated circuit according to claim 6,

wherein the second constant-current-charging control circuit includes:

a third operational amplifier circuit configured to amplify a difference voltage between the detected battery voltage second charging current value signal from the second charging-current-detecting circuit section and the first reference voltage, and output the amplified difference voltage as a third amplified difference voltage signal; and

a third transistor having a third control electrode to which the third amplified difference voltage signal from the third operational amplifier circuit is input;

wherein the second constant-voltage-charging control circuit includes a fourth transistor having a fourth control electrode to which the first amplified difference voltage signal from the first operational amplifier circuit is input; and

wherein the third and fourth transistors are connected in series between the second control electrode of the second charging transistor and a portion having a given voltage.

8. The charging control semiconductor integrated circuit according to claim 4, wherein the second charging-control circuit section includes a second constant-current-charging control circuit configured to control, on the basis of the second charging current value signal from the second charging-current-detecting circuit section, the second charging transistor to output the second charging current.

9. The charging control semiconductor integrated circuit according to claim 8,

wherein the second constant-current-charging control circuit includes:

a third operational amplifier circuit configured to amplify a difference voltage between the first charging current value signal from the first charging-current-detecting circuit section and the second charging current value signal from the second charging-current-detecting circuit section, and output the amplified difference voltage as a third amplified difference voltage signal; and

a third transistor having a third control electrode to which the third amplified difference voltage signal from the third operational amplifier circuit is input; and

wherein the third transistor is connected between the second control electrode of the second charging transistor and a portion having a given voltage.

10. The charging control semiconductor integrated circuit according to claim 2, wherein the second charging control circuit includes a second constant current charging control circuit configured to control, on the basis of the second charging current value signal from the second charging-current-detecting circuit section, the second charging transistor to output the second charging current.

11. The charging control semiconductor integrated circuit according to claim 1, wherein the second constant-current-charging control circuit includes:

a third operational amplifier circuit configured to amplify a difference voltage between the second charging current value signal from the second charging-current-detecting circuit section, and output the amplified difference voltage as a third amplified difference voltage signal;

a third transistor having a third control electrode to which the third amplified difference voltage signal from the third operational amplifier circuit is input; and

a driving control circuit configured to control driving of the third operational amplifier circuit depending on the first charging current value signal from the first charging-current-detecting circuit section, and

wherein the third transistor is connected between the second control electrode of the second charging transistor and a portion having a given voltage, and the third transistor turns off the second transistor to place the second transistor in a shutoff state by stopping an operation of the third operational amplifier circuit when the first charging current is not greater than a given value.

12. The charging control semiconductor integrated circuit according to claim 2, wherein the second charging-current-detecting circuit section includes:

a second constant-current-charging control circuit configured to control, on the basis of the first and second charging current value signals from the first and second charging-current-detecting circuit sections, respectively, the second charging transistor to output the second charging current so that the battery voltage is constant at a given value; and

a second constant-voltage-charging control circuit configured to control, on the basis of the first charging current value signal from the first charging-current-detecting circuit section, the second charging transistor to output the second charging current so that the battery voltage is constant at a given value.

13. The charging control semiconductor integrated circuit according to claim 12,

wherein the second constant-current-charging control circuit includes:

a third operational amplifier circuit configured to amplify a difference voltage between the first and second charging current value signals from the first and second charging-current-detecting circuit sections, respectively, and output the amplified difference voltage as a third amplified difference voltage signal; and

a third transistor having a third control electrode to which the third amplified difference voltage signal from the third operational amplifier circuit is input; and

wherein the second constant-voltage-charging control circuit includes;

a fourth operational amplifier circuit configured to amplify a difference voltage between the first and second charging current value signals from the first and second charging-current-detecting circuit sections, respectively, and output the amplified difference voltage as a fourth amplified difference voltage signal; and

a fourth transistor having a fourth control electrode to which the fourth amplified difference voltage signal from the fourth operational amplifier circuit is input; and

wherein the third and fourth transistors are connected in series between the second control electrode of the second charging transistor and a portion having a given voltage.

14. The charging control semiconductor integrated circuit according to claim 2, wherein the second charging-control circuit section includes:

a second constant-current-charging control circuit configured to control, on the basis of the second charging current value signal from the second charging-current-detecting circuit section, the second charging transistor to output the second charging current so that the battery voltage is constant at a given value; and

a second constant-voltage-charging control circuit configured to control, on the basis of the first charging current value signal from the first charging-current-detecting circuit section, the second charging transistor to output the second charging current so that the battery voltage is constant at a given value.

15. The charging control semiconductor integrated circuit according to claim 14,

wherein the second constant-current-charging control circuit includes:

a third operational amplifier circuit configured to amplify a difference voltage between the second charging current value signal from the second charging-current-detecting circuit section and a given fourth reference voltage, and output the amplified difference voltage as a third amplified difference voltage signal; and

a third transistor having a third control electrode to which the third amplified difference voltage signal from the third operational amplifier circuit is input;

wherein the second constant-current-charging control circuit includes;

a fourth operational amplifier circuit configured to amplify a difference voltage between the first charging current value signal from the first charging-current-detecting circuit section and a given third reference voltage, and output the amplified difference voltage as a fourth amplified difference voltage signal; and

a fourth transistor having a fourth control electrode to which the fourth amplified difference voltage signal from the fourth operational amplifier circuit is input; and

wherein the third and fourth transistors are connected in series between the second control electrode of the second charging transistor and a portion having a given voltage.

16. The charging control semiconductor integrated circuit according to claim 15, wherein the third and fourth reference voltages are capable of being changed.