Battery gas gauge reset mechanism

• US 8,232,771 B2
• Filed: 12/08/2008
• Issued: 07/31/2012
• Est. Priority Date: 12/08/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Johnson, Timothy M., Mullins, Scott, Tupman, David John
• Primary Examiner(s): WILLIAMS, ARUN C
• Application Number:
  US12/330,156
• Publication Number:
  US 20100146318A1
• Time in Patent Office: 1,331 Days
• Field of Search: 320/132
• US Class Current: 320/132
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements

Abstract

A gas gauge circuit has a power supply pin, a power return pin, power-on reset capability, and a communications signal pin. A reset control circuit is coupled between the power supply pin and the communications signal pin, or between the power return pin and the communications signal pin. The reset control circuit removes power to the gas gauge circuit in accordance with a control signal asserted on the communications signal pin. Other embodiments are also described and claimed.

Claims

1. An electronic circuit for monitoring a battery, comprising:

a gas gauge circuit having a power supply pin, a power return pin, power-on-reset capability, and a battery parameter output communications signal pin; and

a reset control circuit coupled between (a) the power supply pin or the power return pin and (b) the communications signal pin, to remove power to the gas gauge circuit in accordance with a control signal asserted on the communications pin, wherein the communications signal pin is an output to send battery monitoring data to a separate host controller;

wherein the control signal is received on the signal pin in a reverse direction; and

wherein in response to receiving the control signal on the communications pin, the reset control circuit is to cut off current to the power supply pin from a battery supply line, or cut off current from the power return pin to a battery return line.

2. The electronic circuit of claim 1 wherein the gas gauge circuit comprises a processor and memory, the memory stores instructions that when executed by the processor (a) monitor energy output of a battery, (b) compute a measure of remaining energy in the battery, and (c) signal the computed measure to a host processor using the communications pin.

3. The electronic circuit of claim 2 wherein the communications pin is a serial communications protocol signal pin.

4. The electronic circuit of claim 2 wherein the reset control circuit is to remove power to the gas gauge, by cutting off current to the power supply pin from a battery supply line.

5. The electronic circuit of claim 4 wherein the reset control circuit is to assert the control signal on the communications pin by overdriving the communications pin, in response to a command from the host processor of a mobile device.

6. The electronic circuit of claim 5 wherein the reset control circuit comprises a transistor switch coupled to pass current from the battery supply line to the power supply pin, a control electrode of the transistor being coupled to the communications pin.

7. The electronic circuit of claim 6 wherein the reset control circuit is to overdrive the communications pin so that the control electrode reaches a voltage of the battery supply line to thereby turn off the transistor switch.

8. The electronic circuit of claim 2 wherein the reset control circuit is to remove power to the gas gauge, by cutting off current from the power return pin to a battery return line.

9. The electronic circuit of claim 8 wherein the reset control circuit is to assert the control signal on the communications pin, by maintaining a fixed logic low level on the communications pin for a time interval that is longer than the longest logic low level for a transaction on the communications pin.

10. The electronic circuit of claim 1, wherein as a result of receiving the control signal asserted on the communications pin, the reset control circuit is to remove power to the gas gauge circuit without resetting or removing power to the separate host controller.

11. The electronic circuit of claim 1, wherein as a result of receiving the control signal asserted on the communications pin, removing power to the gas gauge circuit.

12. The electronic circuit of claim 1, wherein removing power to the gas gauge circuit comprises removing power only to the gas gauge circuit.