Data transfer systems with power management

1. A controller for transferring data between a host and a storage medium, said controller comprising:

a data transfer unit transferring said data according to control commands from said host if said data transfer unit is enabled; and

a control unit, coupled to said data transfer unit, that receives a status signal indicating whether said storage medium is coupled to a socket of said controller, that controls said data transfer unit according to said status signal, and that provides a plurality of interruption signals to said host,

wherein power and a clock signal for said control unit are cut off if said status signal indicates that said storage medium is decoupled from said socket.

2. The controller as claimed in claim 1 , wherein said power and said clock signal for said control unit are turned on if said status signal indicates that said storage medium is coupled to said socket.

3. The controller as claimed in claim 1 , wherein said control unit comprises a card detection circuit which receives said status signal, and enables and disables said data transfer unit according to said status signal.

4. The controller as claimed in claim 3 , wherein said card detection circuit enables said data transfer unit if said status signal indicates that said storage medium is coupled to said socket, and wherein said card detection circuit disables said data transfer unit if said status signal indicates that said storage medium is decoupled from said socket.

5. The controller as claimed in claim 1 , wherein said power and said clock signal for said data transfer unit are turned on if said status signal indicates that said storage medium is coupled to said socket, and wherein said power and said clock signal for said data transfer unit are cut off if said status signal indicates that said storage medium is decoupled from said socket.

6. The controller of claim 1 , further comprising:

a filter, coupled to said socket, that generates said status signal provided to both said control unit and said host.

7. A data transfer system comprising:

a host;

a storage medium;

a controller coupled between said host and said storage medium and operable for transferring data between said host and said storage medium, said controller further comprising:

a data transfer unit transferring data according to control commands from said host if said data transfer unit is enabled;

a control unit, coupled to said data transfer unit, that receives a status signal indicating whether said storage medium is coupled to a socket of said controller, that controls said data transfer unit according to said status signal, and that provides a plurality of interruption signals to said host,

wherein power and a clock signal for said control unit are cut off if said status signal indicates that said storage medium is decoupled from said socket.

8. The data transfer system as claimed in claim 7 , wherein said power and said clock signal for said control unit are turned on if said status signal indicates that said storage medium is coupled to said socket.

9. The data transfer system as claimed in claim 7 , wherein said control unit enables said data transfer unit if said status signal indicates that said storage medium is coupled to said socket, and wherein said control unit disables said data transfer unit if said status signal indicates that said storage medium is decoupled from said socket.

10. The data transfer system as claimed in claim 7 , wherein said power and said clock signal for said data transfer unit are turned on if said status signal indicates that said storage medium is coupled to said socket, and said power and said clock signal for said data transfer unit are cut off if said status signal indicates that said storage medium is decoupled from said socket.

11. The data transfer system as claimed in claim 7 , wherein said host further comprises a pin, which is operable for receiving said status signal from said filter.

12. The data transfer system as claimed in claim 7 , wherein said storage medium comprises a flash media card.

13. A method for transferring data information between a host and a storage medium, said method comprising:

transferring a status signal indicating whether a storage medium is coupled to a socket of a controller to said host;

cutting off power and a clock signal to a control unit of said controller if said status signal indicates that said storage medium is decoupled from said socket;

transferring said data according to control commands from said host if a data transfer unit of said controller is enabled.

14. The method as claimed in claim 13 , further comprising:

turning on said power and said clock signal to said control unit of said controller if said status signal indicates that said storage medium is coupled to said socket.

15. The method as claimed in claim 13 , further comprising:

turning on said power and said clock signal to said data transfer unit if said status signal indicates that said storage medium is coupled to said socket; and

cutting off said power and said clock signal to said data transfer unit if said status signal indicates that said storage medium is decoupled from said socket.

16. The method as claimed in claim 13 , further comprising:

enabling and disabling said data transfer unit by said control unit according to said status signal.

17. The method as claimed in claim 16 , further comprising:

enabling said data transfer unit if said status signal indicates that said storage medium is coupled to said socket, and

disabling said data transfer unit if said status signal indicates that said storage medium is decoupled from said socket.