System for charging monitoring batteries for a microprocessor based method

• US 6,377,028 B1
• Filed: 07/29/1996
• Issued: 04/23/2002
• Est. Priority Date: 10/23/1990
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Davies, William F. Jr., Armstrong, Gene Lee II, Freeman, David Louis
• Primary Examiner(s): Dougherty, Thomas M.
• Application Number:
  US08/681,596
• Time in Patent Office: 2,094 Days
• Field of Search: 307/48, 307/66, 320/151, 320/152, 320/156, 320/136, 320/134
• US Class Current: 320/136
• CPC Class Codes: H02J 7/0049 Detection of fully charged condition

Abstract

A battery monitoring/control device includes a monitor/control device (35) that is operable to be integrated with a microprocessor system. The system includes a CPU (12) that interfaces with a data bus (14) and an address bus (16). The CPU (12) interfaces through a data line (40) with the control/monitor device (35) and control lines (28) and (34). Commands and data can be input to the control/monitor circuit (35) and data received therefrom. The control/monitor device (35) includes a controller/data register block (36) and a battery charge control/monitor block (44). The device (35) is operable to monitor the battery voltage of a secondary battery (46) during charging thereof and to control the rate of charge through a transistor (66). The battery monitor (90) determines when the voltage on the battery (46) reaches a predetermined level indicating full-charge. A discharge circuit (94) controls a discharge transistor (72) to discharge the battery (46) through a sense resistor (68) for conditioning of the battery. The system receives current from the battery (46) through the resistor (68), the current monitored by a Gas Gauge monitor (92). The Gas Gauge monitor (92) maintains a measurement of the capacity of the battery (46). Control and status information is maintained in control/status register (56), which are set to a default value in a default register (57) upon power up. The CPU (12) can store control information in the registers (56) in order to control the device (35). Further, status information of the device (35) can be stored in the register (56) for access by the CPU (12) through a bus interface (52).

Claims

1. A method for determining the charge state of a battery that is used by a system, which system during operation thereof comprises a system load that can vary in accordance with the operation of the system and which charge state will be charged in accordance with the variable system load and a function thereof, comprising the steps of:

operating the system with a battery such that the battery load is the system load;

determining the amount of charge removed from the battery while under system load and while the battery is discharging, wherein the system load and the current supplied thereto during the operation of the system determine the discharge profile that is a function of the varying system load;

initiating the step of determining at a first charge level;

terminating the step of determining at a second charge level that is below the first charge level; and

defining the capacity of the battery as the amount of charge removed from the battery and delivered to the system load from the step of initiating to the step of terminating and storing the determined capacity in a storage device.

2. The method of claim 1, wherein the step of determining is a continuous operation.

3. The method of claim 1, wherein the step of initiating comprises initiating the step of determining at a charge level that represents a substantially fully charged battery.

4. The method of claim 1, wherein the step of terminating comprises the step of terminating the step of determining when the voltage of the battery is determined to be below a predetermined end-of-discharge value.

5. The method of claim 1, and further comprising:

providing a communication port for allowing access to the storage device; and

transferring data into the storage device through the communication port and accessing data from the storage device for output through the communication port to an external device.

6. The method of claim 5, and further comprising:

receiving through the communication port an externally generated command and storing the command in the storage device; and

further comprising the step of controlling the step of determining, the step of initiating and the step of terminating in response to receiving the command and in accordance with the contents of the command.

7. The method of claim 5, wherein the information transmitted from the storage device through the communication port to the external device is the capacity of the battery.