Variable-frequency sampling of battery voltage to determine fuel gauge power mode

1. A fuel gauge comprising:

a voltage detection logic circuit coupled with a fluctuation level register memory;

a mode control logic circuit coupled with the voltage detection logic circuit; and

a sampling timer coupled with the voltage detection logic circuit;

wherein the voltage detection logic circuit is configured to repeatedly sample a voltage from a battery using the sampling timer to measure a voltage swing and a rate of change of the voltage and generate data values that correspond with the voltage swing and the rate of change of the voltage;

wherein the voltage detection logic circuit is configured to use the data values corresponding with the voltage swing and the rate of change of the voltage to send a signal to the mode control logic circuit to increase a power mode of the fuel gauge if

the data values corresponding with the voltage swing are greater than a voltage swing threshold value from the fluctuation level register memory and

the data values corresponding with the rate of change of the voltage are greater than a rate of change threshold value from the fluctuation level register memory; and

wherein the voltage detection logic circuit is configured to use the data values corresponding with the voltage swing and the rate of change of the voltage to send a signal to the mode control logic circuit to decrease the power mode of the fuel gauge if

the data values corresponding with the voltage swing are less than a voltage swing threshold value from the fluctuation level register memory and

the data values corresponding with the rate of change of the voltage are less than a rate of change threshold from the fluctuation level register memory.

2. The fuel gauge of claim 1 , wherein the voltage detection logic circuit is configured to repeatedly sample the voltage at a sampling frequency corresponding to the power mode of the fuel gauge using the sampling timer.

3. The fuel gauge of claim 2 , wherein the power mode is selected from at least two different power modes, and wherein one of the at least two different power modes is associated with more frequent sampling of the voltage by the voltage detection logic circuit, and wherein another one of the at least two different power modes is associated with less frequent sampling of the voltage by the voltage detection logic circuit.

4. The fuel gauge of claim 1 , wherein the mode control logic circuit is configured to change the power mode from one of a stand by mode, a relax mode, an operation mode and an active mode.

5. The fuel gauge of claim 1 , wherein the fuel gauge is configured to maintain its power mode if the data values corresponding with the voltage swing fails to meet or exceed the voltage swing threshold.

6. The fuel gauge of claim 1 , wherein the fuel gauge is configured to switch to a lower power mode if the data values corresponding with the voltage swing are zero.

7. The fuel gauge of claim 1 , wherein the fuel gauge is configured to couple with an electronic device selected from the group consisting of: a smart phone, a tablet, a laptop, a digital camera, and a handheld game console.

8. The fuel gauge of claim 1 , wherein the voltage detection logic circuit is configured to select the power mode based on a combination of the data values corresponding with the voltage swing and the data values corresponding with the rate of change of the voltage.

9. The fuel gauge of claim 1 , wherein the fuel gauge is configured to maintain the power mode when one of the following is true:

the data values corresponding to the voltage swing are less than the voltage swing threshold and the data values corresponding with the rate of change of the voltage is greater than a rate of change threshold; and

the data values corresponding with the rate of change of the voltage are less than a rate of change threshold and the data values corresponding with the voltage swing are greater than a voltage swing threshold.

10. A fuel gauge, comprising:

a voltage detection logic circuit coupled with a fluctuation level register memory;

a mode control logic circuit coupled with the voltage detection logic circuit; and

a sampling timer coupled with the voltage detection logic circuit;

wherein the voltage detection logic circuit is configured to repeatedly sample a voltage from a battery using the sampling timer and measure a voltage swing and a rate of change of the voltage and generate data values that correspond with the voltage swing and the rate of change of the voltage;

wherein the voltage detection logic circuit is configured to use the data values corresponding with the voltage swing and the rate of change of the voltage to send a signal to the mode control logic circuit to increase a power mode of the fuel gauge if the data values corresponding with the voltage swing are greater than a voltage swing threshold value from the fluctuation level register memory and the data values corresponding with the rate of change of the voltage are greater than a rate of change threshold value from the fluctuation level register memory; and

wherein the voltage detection logic circuit is configured to use the data values corresponding with the voltage swing and the rate of change of the voltage to send a signal to the mode control logic circuit to decrease the power mode of the fuel gauge if the data values corresponding with the voltage swing are less than a voltage swing threshold value from the fluctuation level register memory and the data values corresponding with the rate of change of the voltage are less than a rate of change threshold.

11. The fuel gauge of claim 10 , wherein, while operating within a single fuel gauge power mode, the sampling timer varies a sampling frequency at which the voltage detection logic samples the voltage.

12. The fuel gauge of claim 10 , wherein the fluctuation level register memory is configured to store the voltage swing threshold against which the fuel gauge compares a degree to which the voltage swings between samples and is configured to store the rate of change threshold against which the fuel gauge compares how often the voltage changes, and wherein the voltage detection logic circuit uses the comparisons to send a signal to the mode control logic circuit to select the power mode.

13. The fuel gauge of claim 10 , wherein a sampling frequency of the sampling timer at which the voltage detection logic is configured to sample the voltage is based on a currently-enabled power mode of the fuel gauge.

14. The fuel gauge of claim 10 , wherein, if the voltage detection logic circuit determines that the voltage does not change over a predetermined number of consecutive samples, it is configured to send a signal to the mode control logic circuit to switch to a lower power mode.

15. A method for conserving power, comprising:

repeatedly sampling a voltage using a voltage detection logic circuit coupled with a sampling timer;

measuring a voltage swing and a rate of change of the voltage using the voltage detection logic circuit;

generating data values that correspond with the voltage swing and the rate of change of the voltage;

using the data values that correspond with the voltage swing and the rate of change of the voltage, sending a signal using the voltage detection logic circuit to a mode control logic circuit to increase a power mode of the fuel gauge if

the data values corresponding with the voltage swing are greater than a voltage swing threshold value stored in a fluctuation level register memory coupled to the voltage detection logic circuit and

the data values corresponding with the rate of change of the voltage are greater than a rate of change threshold value stored in the fluctuation level register memory; and

using the data values corresponding with the voltage swing and the rate of change of the voltage, sending a signal using the voltage detection logic circuit to the mode control logic circuit to decrease the power mode of the fuel gauge if

the data values corresponding with the voltage swing are less than the voltage swing threshold value stored in the fluctuation level register memory and

the data values corresponding with the rate of change of the voltage are less than the rate of change threshold.

16. The method of claim 15 , wherein the fuel gauge power mode is selected from the group consisting of: a standby mode, a relaxed mode, an operation mode, and an active mode.

17. The method of claim 16 , wherein the voltage detection logic circuit, using the sampling timer, samples the voltage at a first sampling frequency during the relaxed mode, at a second sampling frequency during the operation mode, and at a third sampling frequency during the active mode, and wherein the second sampling frequency is greater than the first sampling frequency but less than the third sampling frequency.

18. The method of claim 15 , further comprising varying the sampling frequency while operating within a single fuel gauge power mode.

19. The method of claim 15 , wherein, if the data values corresponding with a greatest voltage swing over a predetermined number of consecutive voltage samples are equal to or greater than the voltage swing threshold and if the data values corresponding with the rate of change of the voltage over the predetermined number of consecutive voltage samples are equal to or greater than a rate of change threshold, the mode control logic circuit is configured to switch to a higher power mode.

20. The method of claim 15 , wherein the voltage detection logic circuit is configured to select the power mode based on a combination of the data values corresponding with the voltage swing and the data values corresponding with the rate of change of the voltage.