Memory device, operation method of a memory device, and operation method of a memory controller
A method of operating a memory device includes receiving, from a memory controller, an operation command that is synchronized with a clock signal, receiving a data clock signal having a full-rate frequency and a synchronization pattern provided by at least one of a plurality of data signals. The clock signal and the data clock signal are then synchronized using a synchronization operation based on the synchronization pattern. The data clock signal may be received after a first delay time passes from a time point at which the operation command is received. The first delay time is a delay time necessary to prepare the synchronization operation.
1. A method of operating a memory device, comprising:
receiving, from a memory controller, an operation command that is synchronized with a clock signal;
receiving, from the memory controller, a data clock signal having a full-rate frequency and a synchronization pattern provided by at least one of a plurality of data signals; and
synchronizing the clock signal and the data clock signal using a synchronization operation based on the synchronization pattern.
2. The method of claim 1 , wherein the data clock signal is received immediately after a first delay time passes from a time point at which the operation command is received.
3. The method of claim 2 , wherein the first delay time is a delay time necessary to prepare the synchronization operation.
4. The method of claim 1 , wherein said synchronizing includes:
generating four split data clocks based on the data clock signal having the full-rate frequency;
sampling the synchronization pattern based on the four split data clocks and a synchronization signal; and
then, when a sampling result of the sampling does not correspond to at least a part of the synchronization pattern, swapping some of the four split data clocks with others of the four split data clocks.
5. The method of claim 4 ,
wherein the synchronization pattern includes eight bits; and
wherein four lowermost bits of the synchronization pattern are sampled based on the four split data clocks and the synchronization signal.
6. The method of claim 1 , wherein the synchronization pattern is received through the at least one of the plurality of data signals from a time point at which the data clock signal having the full-rate frequency is received.
7. The method of claim 1 , wherein the synchronization pattern is received through the at least one of the plurality of data signals after a second delay time passes from a time point at which the data clock signal having the full-rate frequency is received.
8. The method of claim 1 , further comprising:
sending read data to the memory controller or receiving write data from the memory controller, after said synchronizing is performed and a third delay time passes from a time point at which the data clock signal having the full-rate frequency is received.
9. The method of claim 1 , wherein, when the operation command includes information about a minimum delay synchronization operation, then the data clock signal having the full-rate frequency commences to be received from the memory controller while the operation command is being received.
10. The method of claim 9 , wherein, when the operation command includes the information about the minimum delay synchronization operation, then the synchronization operation is performed while the operation command is being received.
11. The method of claim 9 , wherein, when the operation command includes the information about the minimum delay synchronization operation, the synchronization operation is commenced after the operation command is received.
12. The method of claim 1 , wherein information about the synchronization pattern is set in a mode register by the memory controller.
13. The method of claim 1 , wherein the memory device is an LPDDR SDRAM device.
14. A method of operating a memory controller, comprising:
sending a CAS command and a read command from the memory controller to a memory device, which is electrically coupled to the memory controller;
then, immediately after a first delay time passes from a time point at which the CAS command is sent, sending a data clock signal having a full-rate frequency to the memory device along with a synchronization pattern that is provided as at least one of a plurality of data signals; and
after a second delay time passes from a time point at which the data clock signal commences to be sent, receiving read data from the memory device through the plurality of data signals.
15. The method of claim 14 , further comprising:
receiving a read data strobe signal from the memory device; and
wherein the read data are received in synchronization with the read data strobe signal.
16. The method of claim 14 , wherein, while the read command is being sent to the memory device, a data clock signal having a full-rate frequency is also sent to the memory device.
17. The method of claim 14 ,
wherein the synchronization pattern is sent to the memory device after a third delay time passes from a time point at which the data clock signal having the full-rate frequency commences to be sent to the memory device; and
wherein the third delay time is shorter than the second delay time.
18. The method of claim 14 , further comprising:
loading information about the synchronization pattern into a mode register of the memory device.
19. A memory device, comprising:
a memory core;
a command/address decoder configured to receive a clock signal from a memory controller and to decode a command/address signal received from the memory controller based on the clock signal;
a data clock splitter configured to receive a data clock signal of a full rate from the memory controller and to generate four split data clocks by splitting the data clock signal;
a reception circuit configured to sequentially output write data received through a plurality of data signals from the memory controller to the memory core in synchronization with the four split data clocks; and
a transmission circuit configured to send read data received from the memory core to the memory controller through the plurality of data signals in synchronization with the four split data clocks; and
wherein, while the data clock signal of the full rate is being received from the memory controller, the data clock splitter is further configured to perform a synchronization operation on the data clock signal based on a synchronization pattern received through at least one of the plurality of data signals.
20. The memory device of claim 19 ,
wherein the command/address decoder is further configured to generate a synchronization signal based on a decoding result;
wherein the data clock splitter samples the synchronization pattern based on the four split data clocks in response to the synchronization signal; and
wherein, when a sampled value does not correspond to at least a part of the synchronization pattern, the data clock splitter performs the synchronization operation by swapping some of the four split data clocks with others of the four split data clocks.