Gas gauge implementation

• US 6,154,012 A
• Filed: 10/13/1999
• Issued: 11/28/2000
• Est. Priority Date: 10/13/1999
• Status: Expired due to Term

• Current Assignee: Xicor LLC (Renesas Electronics Corporation)
• Original Assignee: Xicor LLC (Renesas Electronics Corporation)
• Inventors: Drori, Joseph
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): LUK, LAWRENCE W
• Application Number:
  US09/417,521
• Time in Patent Office: 412 Days
• Field of Search: 320/162, 320/137, 320/152, 320/157
• US Class Current: 320/162
• CPC Class Codes: G01R 31/3832 without measurement of battery voltage
• CPC Class Codes: H02J 7/00036 Charger exchanging data with battery
• CPC Class Codes: H02J 7/00047 with provisions for charging different types of batteries
• CPC Class Codes: H02J 7/00308 Overvoltage 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

Abstract

A battery management system is provided having a battery management unit (BMU) and an integrated switch and sensor unit (SSU) for accurately measuring the charge state of a rechargeable battery and providing charge protection for the rechargeable battery. The system uses a charger unit to charge the rechargeable battery and a combination sensor switch circuit having a first and second mirror current proportional to the current used to charge and discharge the rechargeable battery. The switch function in sensor switch circuit disconnects the battery from receiving additional charge when a disconnect signal is provided. A battery management unit is used to detect conditions such as over voltage, over current, and over temperature associated with the rechargeable battery and transmit the disconnect signal to the sensor and switch unit when at least one condition is detected.

Claims

1. An battery management unit for measuring a charge level in a rechargeable battery and terminating the charging of the rechargeable battery if the charge levels exceed one or more predetermined thresholds, comprising:

a charger unit capable of charging the rechargeable battery;

a sensor and switch unit having a first and second mirror current proportional to a current used to charge and discharge the rechargeable battery, the sensor and switch unit operable to disconnect the rechargeable battery from the load and charger when a disconnect signal is provided; and

a battery management unit that detects over voltage condition associated with the rechargeable battery using the mirror currents and transmits the disconnect signal to the sensor and switch unit to enable the battery to be disconnted from the load and charger.