Secondary battery protection semiconductor device

• US 20090058365A1
• Filed: 08/28/2008
• Published: 03/05/2009
• Est. Priority Date: 08/29/2007
• Status: Active Grant

• Current Assignee: RICOH Electronic Devices Co., Ltd. (Nisshinbo Holdings Incorporated)
• Original Assignee: Ricoh Company Limited
• Inventors: Goto, Tomoyuki
• Granted Patent: US 8,148,944 B2
• Time in Patent Office: Days
• US Class Current: 320/134
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 10/443 in response to temperature
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H01M 10/486 for measuring temperature
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00304 Overcurrent protection
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: H02J 7/00309 Overheat or overtemperature protection
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A disclosed secondary battery protection semiconductor device protects the secondary battery by detecting values of at least plural detection items corresponding to the secondary battery including the detection items of overcharge, overdischarge, charge overcurrent, discharge overcurrent, short-circuit current, and overheat; comparing the detected values with corresponding detection levels that are determined beforehand for each of the detection items; and based on the comparison results, turning on/off a discharge control transistor and a charge control transistor that are series-connected to the secondary battery. Among the plural detection items, a first value of a first detection item is detected, and a detection level of a second detection item is changed in accordance with the first value.

Claims

1. A secondary battery protection semiconductor device for protecting a secondary battery, wherein the secondary battery protection semiconductor device protects the secondary battery by detecting values of at least plural detection items corresponding to the secondary battery including the detection items of overcharge, overdischarge, charge overcurrent, discharge overcurrent, short-circuit current, and overheat;

comparing the detected values with corresponding detection levels that are determined beforehand for each of the detection items; and

based on the comparison results, turning on/off a discharge control transistor and a charge control transistor that are series-connected to the secondary battery, wherein;

among the plural detection items, a first value of a first detection item is detected, and a detection level of a second detection item is changed in accordance with the first value.

2. The secondary battery protection semiconductor device according to claim 1, comprising:

an overcharge detection circuit configured to output an overcharge detection signal in response to detecting that a voltage of the secondary battery undergoing a charging operation is at least higher than or equal to a first voltage that is determined beforehand;

a control circuit configured to stop the charging operation of the secondary battery in response to the overcharge detection signal; and

a temperature detection circuit configured to detect at least one of a temperature of the secondary battery and temperatures of the discharge control transistor and the charge control transistor, wherein;

in the event that the temperature detected by the temperature detection circuit is higher than or equal to a predetermined temperature, the overcharge detection circuit outputs the overcharge detection signal in response to detecting that the voltage of the secondary battery undergoing the charging operation is higher than or equal to a second voltage which is lower than the first voltage.

3. The secondary battery protection semiconductor device according to claim 1, comprising:

an overcharge detection circuit configured to output an overcharge detection signal in response to detecting that a voltage of the secondary battery undergoing a charging operation is at least higher than or equal to a first voltage that is determined beforehand;

a control circuit configured to turn off the charge control transistor and stop the charging operation of the secondary battery in response to the overcharge detection signal; and

a temperature detection circuit configured to detect at least one of a temperature of the secondary battery and temperatures of the discharge control transistor and the charge control transistor, wherein;

the secondary battery protection semiconductor device selects a first mode or a second mode in response to a switching signal;

in the first mode, in the event that the temperature detected by the temperature detection circuit is higher than or equal to a predetermined temperature, the charge control transistor is turned off and the charging operation of the secondary battery is stopped in response to an output signal of the temperature detection circuit; and

in the second mode, in the event that the temperature detected by the temperature detection circuit is higher than or equal to the predetermined temperature, the overcharge detection circuit outputs the overcharge detection signal in response to detecting that the voltage of the secondary battery undergoing the charging operation is higher than or equal to a second voltage which is lower than the first voltage, and the charge control transistor is turned off and the charging operation of the secondary battery is stopped in response to the overcharge detection signal.

4. The secondary battery protection semiconductor device according to claim 3, wherein:

the switching signal comprises a signal applied from an external terminal, or a signal generated by a circuit configuration or a setting unit configured to generate a predetermined voltage level.

5. A battery pack using the secondary battery protection semiconductor device according to claim 1.

6. A battery pack using the secondary battery protection semiconductor device according to claim 2.

7. A battery pack using the secondary battery protection semiconductor device according to claim 3.

8. A battery pack using the secondary battery protection semiconductor device according to claim 4.

9. An electronic device using the battery pack according to claim 5.

10. An electronic device using the battery pack according to claim 6.

11. An electronic device using the battery pack according to claim 7.

12. An electronic device using the battery pack according to claim 8.