NFC module powering

1. An electronic device, comprising:

a powering circuit configured to provide a supply voltage; and

a near-field communication module having a power supply input coupled to receive said supply voltage from the powering circuit and a field detector;

wherein said near-field communication module is configurable for operation in a full power mode where said field detector operates to detect presence of a field for near-field communication with a detection rate at or higher than a first frequency and in a low power mode where said field detector operates to detect presence of said field for near-field communication with a detection rate at a second frequency less than the first frequency; and

wherein when in said low power mode, said powering circuit is configured to periodically provide the supply voltage to said near-field communication module only at times when the field detector attempts to detect presence of said field for near-field communication.

2. The device according to claim 1 , further comprising a control circuit coupled to the powering circuit, and wherein, when said near-field communication module is in the low power mode, said control circuit is configured to periodically start said powering circuit.

3. The device according to claim 2 , wherein the control circuit comprises a counter.

4. The device according to claim 3 , wherein, when said near-field communication module enters the low power mode, the counter is started, and wherein the powering circuit is started by the control circuit when a value of the counter reaches a threshold value.

5. The device according to claim 4 , wherein, when said near-field communication module is in the low power mode and when the value of the counter reaches a limiting value that is greater than the threshold value, the powering circuit is stopped by the control circuit and the value of the counter is reset.

6. The device according to claim 2 , wherein said control circuit further comprises a reference voltage generating circuit.

7. The device according to claim 6 , wherein the reference voltage generating circuit is a band gap circuit.

8. The device according to claim 1 , wherein, when said near-field communication module is in the low power mode and wherein when the powering circuit is started by the control circuit, the field detector of said near-field communication module is started.

9. The device according to claim 1 , wherein said near-field communication module further comprises a comparison circuit configured to compare a frequency of an electric field detected by said field detector with a reference frequency.

10. The device according to claim 9 , wherein said comparison circuit is a state machine.

11. The device according to claim 9 , wherein, when said near-field communication module is in the low power mode and when said comparison circuit determines that the frequency of the field detected by said field detector is substantially equal to the reference frequency, an alert signal is generated.

12. The device according to claim 11 , wherein substantially equal is satisfied if within an error margin in the order of 10%.

13. The device according to claim 11 , further comprising a circuit for powering a processor configured to receive said alert signal.

14. The device according to claim 13 , wherein said circuit for powering comprises a voltage regulator configured to regulate an internal power supply voltage and deliver said supply voltage to said near-field communication module.

15. The device according to claim 1 , wherein said powering circuit comprises a reference voltage generating circuit.

16. The device according to claim 15 , wherein the reference voltage generating circuit is a band gap circuit.