Universal serial bus charger for a mobile device
View Patent ↗In accordance with the teachings described herein, systems and methods are provided for charging a rechargeable power source in a mobile device through a USB port. A power converter may be used to receive an input voltage from an external power source and generate a charger output having a regulated voltage. A signal generator may be used to generate a charger configuration signal having pre-selected waveform characteristics that are selected to identify operating characteristics of the charging apparatus. A USB connector may be used for coupling the charger output and charger configuration signal to the USB port on the mobile device. The USB connector may include a voltage bus (Vbus) contact coupled to the charger output, a positive data (D+) contact coupled to the charger configuration signal, and a negative data (D−) contact coupled to the charger configuration signal. The charger configuration signal may be transmitted simultaneously to the D+ and D− contacts, such that the D+ and D− contacts are continuously either both in a logic high state or both in a logic low state. The mobile device may be configured to identify the operating characteristics of the charging apparatus from the waveform characteristics of the charger configuration signal and to apply the charger output to recharge the rechargeable power source.
1. A charging apparatus for charging a rechargeable power source in an electronic device through a Universal Serial Bus (USB) port, comprising:
a power converter configured to generate a charger output having a regulated voltage;
a signal generator configured to generate a charger configuration signal having a frequency and duty-cycle; and
a USB connector for coupling the charger output and the charger configuration signal to the USB port of the electronic device;
wherein the electronic device is configured to identify operating characteristics of the charging apparatus from the frequency and duty-cycle of the charger configuration signal and apply the charger output to recharge the rechargeable power source.
2. The charging apparatus of claim 1 , wherein the operating characteristics are identified by the charger configuration signal and include a model number for the charging apparatus.
3. The charging apparatus of claim 1 , wherein the frequency of the charger configuration signal is a constant frequency that is pre-selected to identify a model of the charging apparatus.
4. The charging apparatus of claim 1 , wherein the duty-cycle of the charger configuration signal is a constant duty-cycle that is pre-selected to identify the values of the regulated voltage and maximum current capability of the charger output.
5. The charging apparatus of claim 1 , wherein the power converter receives an input voltage from a household AC power outlet, and wherein the power converter functions as an AC to DC converter.
6. The charging apparatus of claim 1 , wherein the power converter receives an input voltage from a DC power source.
7. The charging apparatus of claim 1 , wherein the signal generator includes a digital timing circuit that is configured to generate the charger configuration signal.
8. The charging apparatus of claim 7 , wherein the digital timing circuit includes:
a digital timer that is configured to generate an output signal having a constant frequency and a constant duty-cycle; and
a switching circuit coupled between the output signal of the digital timer and two contacts of the USB connector, the switching circuit being configured to regulate the peak voltage of the output signal to generate the charger configuration signal.
9. The charging apparatus of claim 8 , wherein the switching circuit is configured to provide a pre-selected resistance.
10. The charging apparatus of claim 1 , wherein the signal generator includes an analog timing circuit that is configured to generate the charger configuration signal.
11. A method of charging a rechargeable power source in an electronic device, comprising the steps of:
generating a charger output having a regulated voltage and a maximum current capacity;
generating a charger configuration signal having pre-selected waveform characteristics, the waveform characteristics including a pre-selected duty-cycle; and
coupling the charger output and charger configuration signal to the electronic device via a Universal Serial Bus (USB) port on the electronic device,
wherein the electronic device is configured to identify the values of the regulated voltage and maximum current capacity of the charger output from the pre-selected duty-cycle of the charger configuration signal and to apply the charger output to recharge the rechargeable power source.
12. The method of claim 11 , wherein the pre-selected waveform characteristics include a pre-selected frequency that identifies a model of a charging apparatus.
13. A method of charging a rechargeable power source in a mobile device, comprising:
detecting an electrical connection between a Universal Serial Bus (USB) port on the device and an external device;
detecting a charger configuration signal; and
determining a regulated voltage value and a maximum current value for the external device from waveform characteristics of the charger configuration signal and configuring the mobile device using the regulated voltage value and the maximum current value to charge the rechargeable power source from the external device.
14. The method of claim 13 , wherein the waveform characteristics of the charger configuration signal include a constant duty-cycle that is pre-selected to identify the regulated voltage value and the maximum current value.
15. The method of claim 13 , further comprising:
determining a model type of the external device from the waveform characteristic of the charger configuration signal and using the model type to configure the mobile device to charge the rechargeable power source from the external device.
16. The method of claim 15 , wherein the waveform characteristics of the charger configuration signal include a constant frequency that is pre-selected to identify the model type.
17. A charging apparatus for charging a rechargeable power source in a mobile device, comprising:
means for generating a charger output having a regulated voltage and a maximum current capacity;
means for generating a charger configuration signal having pre-selected waveform characteristics, the waveform characteristics including a pre-selected duty-cycle; and
means for coupling the charger output and charger configuration signal to the mobile device;
wherein the mobile device is configured to identify the values of the regulated voltage and maximum current capacity of the charger output from the pre-selected duty-cycle of the charger configuration signal and to apply the charger output to recharge the rechargeable power source.