BACK-GATE VOLTAGE GENERATOR CIRCUIT, FOUR-TERMINAL BACK GATE SWITCHING FET, AND CHARGE AND DISCHARGE PROTECTION CIRCUIT USING SAME

• US 20090121683A1
• Filed: 08/14/2007
• Published: 05/14/2009
• Est. Priority Date: 09/19/2006
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Goto, Tomoyuki
• Granted Patent: US 7,710,076 B2
• Time in Patent Office: Days
• US Class Current: 320/134
• 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: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00306 Overdischarge 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 back-gate voltage generator circuit generating a back-gate voltage of a four-terminal back gate switching MOSFET for charge and discharge control is disclosed. The back-gate voltage generator circuit includes first and second n-type MOSFETs connected in series through a common source electrode. A voltage at the common source electrode of the first and second n-type MOSFETS connected in series serves as the back-gate voltage of the four-terminal back gate switching MOSFET, and the back-gate voltage is used as a reference voltage for generating signals for controlling the first and second n-type MOSFETS.

Claims

1. A back-gate voltage generator circuit generating a back-gate voltage of a four-terminal back gate switching MOSFET for charge and discharge control, the back-gate voltage generator circuit comprising:

first and second n-type MOSFETs connected in series through a common source electrode,

wherein a voltage at the common source electrode of the first and second n-type MOSFETS connected in series serves as the back-gate voltage of the four-terminal back gate switching MOSFET, and the back-gate voltage is used as a reference voltage for generating signals for controlling the first and second n-type MOSFETS.

2. The back-gate voltage generator circuit as claimed in claim 1, further comprising:

a first inverter to which a control signal generated from one of detection signals of overcharge, overdischarge, discharge overcurrent, and charge overcurrent of a secondary battery is input; and

a second inverter to which an output of the first inverter is input,

wherein the output of the first inverter is input to a gate of the first n-type MOSFET,

an output of the second inverter is input to a gate of the second n-type MOSFET, and

the back-gate voltage is used as a ground-side reference potential of each of the first inverter and the second inverter.

3. A four-terminal back gate switching MOSFET for charge and discharge control controlled by the back-gate voltage generator circuit as set forth in claim 1.

4. A charge and discharge protection circuit protecting a secondary battery from overcharge, overdischarge, discharge overcurrent, and charge overcurrent by detecting the overcharge, the overdischarge, the discharge overcurrent, and the charge overcurrent of the secondary battery, the charge and discharge protection circuit comprising:

a four-terminal back gate switching MOSFET for charge and discharge control as an FET for the charge and discharge control provided in a charge and discharge path, the four-terminal back gate switching MOSFET being controlled by the back-gate voltage generator circuit as set forth in claim 1.

5. A battery pack, comprising:

a charge and discharge protection circuit protecting a secondary battery from overcharge, overdischarge, discharge overcurrent, and charge overcurrent by detecting the overcharge, the overdischarge, the discharge overcurrent, and the charge overcurrent of the secondary battery, the charge and discharge protection circuit including a four-terminal back gate switching MOSFET for charge and discharge control as an FET for the charge and discharge control provided in a charge and discharge path, the four-terminal back gate switching MOSFET being controlled by the back-gate voltage generator circuit as set forth in claim 1.

6. An electronic apparatus, comprising:

a battery pack including a charge and discharge protection circuit protecting a secondary battery from overcharge, overdischarge, discharge overcurrent, and charge overcurrent by detecting the overcharge, the overdischarge, the discharge overcurrent, and the charge overcurrent of the secondary battery, the charge and discharge protection circuit including a four-terminal back gate switching MOSFET for charge and discharge control as an FET for the charge and discharge control provided in a charge and discharge path, the four-terminal back gate switching MOSFET being controlled by the back-gate voltage generator circuit as set forth in claim 1.

7. A cellular phone, comprising:

a battery pack including a charge and discharge protection circuit protecting a secondary battery from overcharge, overdischarge, discharge overcurrent, and charge overcurrent by detecting the overcharge, the overdischarge, the discharge overcurrent, and the charge overcurrent of the secondary battery, the charge and discharge protection circuit including a four-terminal back gate switching MOSFET for charge and discharge control as an FET for the charge and discharge control provided in a charge and discharge path, the four-terminal back gate switching MOSFET being controlled by the back-gate voltage generator circuit as set forth in claim 1.

8. A digital camera, comprising:

a battery pack including a charge and discharge protection circuit protecting a secondary battery from overcharge, overdischarge, discharge overcurrent, and charge overcurrent by detecting the overcharge, the overdischarge, the discharge overcurrent, and the charge overcurrent of the secondary battery, the charge and discharge protection circuit including a four-terminal back gate switching MOSFET for charge and discharge control as an FET for the charge and discharge control provided in a charge and discharge path, the four-terminal back gate switching MOSFET being controlled by the back-gate voltage generator circuit as set forth in claim 1.

9. An audio apparatus, comprising:

a battery pack including a charge and discharge protection circuit protecting a secondary battery from overcharge, overdischarge, discharge overcurrent, and charge overcurrent by detecting the overcharge, the overdischarge, the discharge overcurrent, and the charge overcurrent of the secondary battery, the charge and discharge protection circuit including a four-terminal back gate switching MOSFET for charge and discharge control as an FET for the charge and discharge control provided in a charge and discharge path, the four-terminal back gate switching MOSFET being controlled by the back-gate voltage generator circuit as set forth in claim 1.

10. A game apparatus, comprising:

a battery pack including a charge and discharge protection circuit protecting a secondary battery from overcharge, overdischarge, discharge overcurrent, and charge overcurrent by detecting the overcharge, the overdischarge, the discharge overcurrent, and the charge overcurrent of the secondary battery, the charge and discharge protection circuit including a four-terminal back gate switching MOSFET for charge and discharge control as an FET for the charge and discharge control provided in a charge and discharge path, the four-terminal back gate switching MOSFET being controlled by the back-gate voltage generator circuit as set forth in claim 1.