Method of operating a semiconductor device having CAL latency function
One controller for controlling operation of a memory device includes an output circuit configured to supply a chip select signal, an address signal, a command signal, and a clock signal to the memory device, and a data processing circuit configured to process read data and write data through a data terminal based on the chip select signal, the address signal, the command signal, and the clock signal supplied by the output circuit. The controller is configured to supply the address signal and the command signal to the memory device a predetermined duration after the output circuit supplies the chip select signal.
1. A method for controlling a semiconductor memory device, the method comprising:
issuing a first mode register set command to the semiconductor memory device to set a command latency to a first latency;
issuing a first chip select signal to the semiconductor memory device;
issuing a first command signal and a first address signal to the semiconductor memory device after a lapse of a first latency from the first chip select signal, wherein the first latency is a sufficient time for activation of command and address receiver circuits in the semiconductor memory device; and
issuing no chip select signals to the semiconductor memory device during a second latency longer than the first latency, wherein the command and address receiver circuits in the semiconductor memory device are deactivated.
2. The method of claim 1 , further comprising:
issuing a second chip select signal to the semiconductor memory device after a period of time less than the second latency following the first chip select signal; and
issuing a second command signal and a second address signal to the semiconductor memory device after a lapse of the first latency from the second chip select signal, wherein the command and address receiver circuits in the semiconductor memory device remain activated from the first command signal to the second command signal.
3. The method of claim 1 , further comprising issuing a second mode register set command to the semiconductor memory device to disable command latency, wherein the command and address receiver circuits in the semiconductor memory device are continuously activated.
4. The method of claim 1 , further comprising providing a clock signal to the semiconductor memory device.
5. The method of claim 4 , wherein the first latency is an integer number of clock periods.
6. The method of claim 5 , wherein the first latency is 3 clock periods.
7. The method of claim 5 , wherein the second latency is 8 clock periods.
8. The method of claim 1 , wherein the first command signal is a read command signal.
9. The method of claim 1 , wherein the first command signal is a write command signal.
10. A method for controlling a semiconductor memory system having a controller and a memory device, the method comprising:
issuing a first mode register set command from the controller;
receiving the first mode register set command to set a command latency to a first latency in the memory device;
issuing a first chip select signal from the controller;
receiving the first chip select signal and activating command and address receiver circuits in the memory device;
issuing a first command signal and a first address signal from the controller after a lapse of a first latency from the first chip select signal;
receiving the first command signal and the first address signal and executing the first command signal in the memory device;
issuing no chip select signals from the controller during a second latency longer than the first latency; and
deactivating the command and address receiver circuits in the memory device after the second latency has elapsed.
11. The method of claim 10 , further comprising:
issuing a second chip select signal from the controller after a period of time less than the second latency following the first chip select signal;
receiving the second chip select signal in the memory device;
issuing a second command signal and a second address signal from the controller after a lapse of the first latency from the second chip select signal; and
receiving the second command signal and the second address signal and executing the second command signal in the memory device, wherein the command and address receiver circuits in the memory device remain activated from the first command signal to the second command signal.
12. The method of claim 10 , further comprising:
issuing a second mode register set command from the controller; and
receiving the first mode register set command to disable command latency in the memory device, wherein the command and address receiver circuits in the memory device are continuously activated.
13. The method of claim 10 , further comprising:
providing a clock signal from the controller; and
receiving the clock signal in the memory device.
14. The method of claim 13 , wherein the first latency is an integer number of clock periods.
15. The method of claim 14 , wherein the first latency is 3 clock periods.
16. The method of claim 14 , wherein the second latency is 8 clock periods.
17. The method of claim 10 , wherein the first command signal is a read command signal.
18. The method of claim 10 , wherein the first command signal is a write command signal.