Hibernate control circuits for battery power switching

1. A vehicle telematics device comprising:

a connector configured to mate with a corresponding connector of a vehicle, wherein the connector includes a main power terminal to receive main power from a main battery of the vehicle;

a local battery internal to the vehicle telematics device and configured to supply battery power;

a power switch coupled to the main power terminal, the local battery, and a power bus of the vehicle telematics device, wherein the power switch is controllable to selectively supply and remove the battery power from the local battery to the power bus while the main power is unavailable;

a hibernatable circuit coupled to the power bus to receive power therefrom; and

a hibernate control circuit coupled to the power switch and configured to control, in response to receipt of a command signal, the power switch to (i) supply the battery power from the local battery to the power bus or (ii) remove the battery power from the power bus,

wherein removal of the battery power from the power bus, while the main power is unavailable, causes the hibernatable circuit to enter a low power state in which the hibernatable circuit draws less power than when the hibernatable circuit is not in the low power state.

2. The vehicle telematics device of claim 1 , wherein the hibernatable circuit is configured to perform a function and wherein the hibernate control circuit is configured to control the power switch, while the main power is unavailable, to (i) supply the battery power to the power bus to cause the hibernatable circuit to exit the low power state and perform the function and (ii) remove the battery power from the power bus to cause the hibernatable circuit to enter the low power state in response to a determination that the hibernatable circuit has performed the function.

3. The vehicle telematics device of claim 1 , further comprising a non-hibernatable circuit configured to send the command signal to the hibernate control circuit to cause the hibernate control circuit to control the power switch to supply the battery power to the power bus to cause the hibernatable circuit to exit the low power state.

4. The vehicle telematics device of claim 1 , wherein the command signal is a periodic command signal based on a clock signal and is periodically received by the hibernate control circuit, wherein the periodic command signal is configured to cause the hibernate control circuit to periodically supply and remove the battery power to the power bus.

5. The vehicle telematics device of claim 4 , further comprising a processor configured to generate the periodic command signal based on a clock signal generated by the processor.

6. The vehicle telematics device of claim 5 , wherein the processor is configured to control the clock signal to adjust a period of the periodic command signal.

7. The vehicle telematics device of claim 1 , further comprising a processor configured to perform a function and, in response to completion of the function, to send the command signal to the hibernate control circuit to control the power switch to remove the battery power from the power bus to cause the hibernatable circuit to enter the low power state.

8. The vehicle telematics device of claim 1 , wherein the hibernatable circuit comprises a processor, and the processor is configured to send the command signal to the hibernate control circuit to control the power switch to remove the battery power from the power bus to cause the processor to enter the low power state.

9. The vehicle telematics device of claim 8 , wherein the processor is further configured to program a counter to generate an additional command signal to the hibernate control circuit to control the power switch to supply the battery power to the power bus to cause the processor to exit the low power state upon expiration of the counter.

10. The vehicle telematics device of claim 1 , further comprising a non-hibernatable circuit coupled to the local battery via a power bus different from the power bus controlled by the power switch, wherein the non-hibernatable circuit is configured to receive power from the local battery while the hibernatable circuit is in the low power state.

11. A method for controlling battery power supplied by a local battery of a vehicle telematics device of a vehicle, the method comprising:

receiving, by the vehicle telematics device, main power from a main battery of the vehicle via a main power terminal of a connector of the vehicle telematics device that is configured to mate with a corresponding connector of the vehicle;

receiving, by a power switch of the vehicle telematics device, a battery power from the local battery, wherein the power switch is controllable to selectively supply and remove the battery power to a power bus of the vehicle telematics device;

controlling, by a hibernate control circuit of the vehicle telematics device and in response to receipt of an enable hibernate command signal while the main power is unavailable, the power switch to remove the battery power from the power bus to cause a hibernatable circuit of the vehicle telematics device coupled to the power bus to enter a low power state in which the hibernatable circuit draws less power than when the hibernatable circuit is not in the low power state; and

controlling, by the hibernate control circuit and in response to receipt of a disable hibernate command signal while the main power is unavailable, the power switch to supply the battery power to the power bus to cause the hibernatable circuit to exit the low power state.

12. The method of claim 11 , further comprising performing, by the hibernatable circuit, a function,

wherein controlling the power switch to supply the battery power to the power bus comprises controlling, by the hibernatable circuit and in response to the disable hibernate command signal, the power switch to cause the hibernatable circuit to exit the low power state and perform the function, and

wherein controlling the power switch to remove the battery power from power bus comprises controlling, by the hibernate control circuit and in response to receipt of the enable hibernate command signal, the power switch to remove the battery power from the power bus to cause a hibernatable circuit to enter a lower power state in response to a determination that the hibernatable circuit has performed the function.

13. The method of claim 11 , further comprising sending, by a non-hibernatable circuit of the vehicle telematics device, the disable hibernate command signal to the hibernate control circuit while the main power is unavailable.

14. The method of claim 11 , further comprising periodically receiving, by the hibernate control circuit, the enable hibernate command signal and the disable hibernate command signal.

15. The method of claim 14 , further comprising:

generating, by a processor of the vehicle telematics device, a clock signal;

periodically sending, by the processor of the vehicle telematics device, the enable hibernate command signal to the hibernate control circuit based on the clock signal; and

periodically sending, by the processor, the disable hibernate command signal to the hibernate control circuit based on the clock signal.

16. The method of claim 15 , further comprising controlling, by the processor, the clock signal to adjust a period at which the processor sends the enable hibernate command signal and the disable hibernate command signal to the hibernate control circuit.

17. The method of claim 11 , further comprising:

performing, by a processor of the vehicle telematics device, a function; and

sending, by the processor, the enable hibernate command signal to the hibernate control circuit in response to a determination by the processor that the function has been completed.

18. The method of claim 11 , wherein the hibernatable circuit comprises a processor, and further comprising:

sending, by the processor, the enable hibernate command signal to the hibernate control circuit to cause processor to enter the low power state.

19. The method of claim 18 , further comprising:

programming, by the processor, a counter; and

receiving, by the hibernate control circuit, the disable hibernate command signal in response to expiration of the counter.

20. The method of claim 11 , further comprising receiving, by a non-hibernatable circuit, power from the local battery while the hibernatable circuit is in the low power state.