Power negotiation in a communications device
View Patent ↗A mobile device is provided having a smart card. The smart card is powered by the mobile device and a maximum power supply value is defined by the mobile device to control the power drawn by the smart card. Provision is made for the smart card to inform the mobile device of the processes supported by the smart card and their classes of current. Provision is also made for the smart card to inform the mobile device whether or not the smart card supports high density memory. The mobile device is operable to use the information provided by the smart card to determine the optimal or best value of electrical current that is to be made available to the smart card.
1. A mobile device comprising:
an interface for a smart card;
a processor operable to define a maximum power supply value for the smart card and to inform the smart card of the maximum power supply value; and
a power circuit operable for providing power to the smart card, up to the defined maximum power supply value;
wherein the processor is operable to request electrical related information for processes supported by the smart card and, in response, is operable to receive data identifying the processes and their classes of current, and wherein said processor is operable to define the maximum power supply value for the smart card in dependence upon the data identifying the processes and their classes of current,
wherein the smart card includes a memory that stores software applications, and a processor that operates in accordance with the software applications,
wherein the processor in the mobile device is operable to receive data from the smart card indicating whether or not the smart card supports high density memory and is operable to define the maximum power supply value for the smart card in dependence upon whether or not the smart card supports high density memory,
wherein the processor in the mobile device is operable to request said electrical related information by sending an Extended Get Interface Power Request to the smart card and is operable to receive data identifying the processes and their classes of current from the smart card,
wherein the processor in the mobile device is operable to send the smart card a Get Interface Power Request prior to sending said Extended Get Interface Power Request and is operable to generate the Extended Interface Power Request in dependence upon a response received from the smart card to the Get Interface Power Request, and
wherein the response to the Get Interface Power Request includes data identifying different voltage classes supported by the smart card and wherein the Extended Interface Power Request requests electrical related information for processes supported by one of the supported voltage classes.
2. A mobile device according to claim 1 , wherein the processor in the mobile device is operable to send multiple Extended Get Interface Power Requests for the different voltage classes supported by the smart card.