Battery monitor
Circuit and methods for tracking the total amount of time that a host device has spent in its high power “activated” state (and optionally idle and hibernate states) and thereby can estimate the total power consumed by the host device. A value representing this time may be send to a remote device to, for example, accurately determine how much of the energy has been consumed by the host device and how much time is left and/or how many operations can be performed before the host device's battery is exhausted.
1. A method for indicating power consumption of a host Radio Frequency Identification (RFID) device, comprising:
generating a tracking signal at a constant frequency when the host RFID device is in a first or second state;
dividing the frequency of the tracking signal when the host RFID device is in the second state,
reducing consumption of power when the RFID device is in the second state; and
storing an indication of the divided frequency,
wherein a derivative of the indication is generated for output to a user for indicating the power consumption of the RFID device.
2. The method of claim 1 , wherein the first state is an active state.
3. The method of claim 1 , wherein the second state is a low-power state.
4. The method of claim 3 , wherein the low-power state is a hibernate state.
5. The method of claim 3 , wherein the low-power state is an idle state.
6. The method of claim 3 , wherein the low-power state is a wait/listen for an activation command state.
7. The method of claim 1 , wherein the RFID device includes an RFID tag.
8. The method of claim 1 , wherein the tracking signal or derivative thereof is capable of being used by a remote device to determine how much life is left in a battery.
9. The method of claim 1 , wherein the tracking signal or derivative thereof is capable of being used by a remote device to determine how much battery energy has been consumed by the RFID device.
10. The method of claim 1 , wherein the tracking signal or derivative thereof is capable of being used by a remote device to determine how many more operations can be performed before a RFID device battery is exhausted.
11. The method of claim 1 , wherein the tracking signal tracks a time spent in the first state.
12. The method of claim 1 , wherein the frequency is reduced to zero.
13. The method of claim 1 , wherein the RFID device includes a temperature sensor.
14. The method of claim 1 , wherein the frequency is reduced by division.
15. The method of claim 1 , wherein a counter is utilized for indicating the power consumption of the RFID device.
16. The method of claim 15 , wherein a value stored in the counter or derivative of the value is compared to a benchmark value.
17. The method of claim 16 , wherein the value stored in the counter is reset after a battery is changed.
18. The method of claim 1 , wherein an alert is generated if a battery level falls below a predetermined amount.
19. The method of claim 1 , wherein the tracking signal is used.
20. The method of claim 1 , wherein the derivative is used.